Drilling Terminology Quick Reference Manual

Refers to the section of the drill string near the drill bit, including components such as the drill bit, drill collar, and drill pipe. The BHA plays a critical role during drilling operations, primarily for directional deviation and trajectory control.

Burst refers to the residual pressure of oil and gas in the annular space of the casing at the wellhead. Specifically, it refers to the pressure of oil and gas in the annular space between the oil and casing at the wellhead, typically measured directly using a surface pressure gauge.

Burst resistance refers to the ability of the casing to resist failure under internal pressure. Specifically, it is the internal pressure at which the casing steel reaches its yield limit under internal pressure.

Bentonite connect is a specialized construction material primarily composed of a mixture of bentonite and cement. Bentonite is a clay mineral primarily composed of montmorillonite, characterized by water absorption, swelling, thixotropy, and binding properties. When bentonite is mixed with cement, it can significantly enhance the properties of the cement, particularly in terms of waterproofing and durability.

Balance method for cementing plug is a technique used during cementing operations that employs a rubber plug to balance internal and external pipe pressures, ensuring the smooth execution of the cementing process. Specifically, the balance method for cementing plug involves using a rubber plug during cementing to isolate the cement slurry and prevent overflow during injection. By controlling the position of the plug, the hydrostatic pressure inside and outside the pipe is balanced, ensuring that the casing and cement slurry remain relatively stationary within a certain depth range, thereby achieving effective zonal isolation.

A tool used for directional drilling at the well bottom with downhole drilling motors. It is formed by bending a standard drill pipe, typically creating an angle 1–1.5 m from the male coupling, resulting in a kinked shape. The working principle of the bend drill pipe is similar to that of a bent coupling, but its directional drilling capability is less than that of the coupling. Additionally, the bend drill pipe can serve as an auxiliary fishing tool. When the wellbore is enlarged and the fish top is difficult to locate against the wall, it can be slowly rotated at a certain angle to probe and locate the fish top.

Bumper is a tool used to resolve stuck pipe incidents during drilling operations. Its primary function is to generate a strong jarring force to loosen the stuck drill string, thereby restoring normal drilling operations. Bumpers are available in various types, including mechanical bumpers, hydraulic bumpers, and hydraulic-mechanical integrated bumpers.

Primarily used to address stuck pipe situations when the drill bit is not at the well bottom. It delivers a downward impact to loosen the stuck section of the drill string. The jar is typically connected above fishing tools and the safety joint. During operation, the drill pipe is first lifted so that the jar housing moves upward a certain distance (e.g. 0.4 m). It is then suddenly lowered, causing the jar housing to strike the coupling below and generate an impact force, thereby loosening the stuck section of the drill string.

The blow out preventer is used during well testing, workover, and well completion operations to close the wellhead and prevent blowout incidents. It integrates both full-sealing and semi-sealing functions, featuring a simple structure, easy to operate, and excellent resistant to high pressure. It is a commonly used safety sealing wellhead device in oilfields to prevent blowouts.

Blowout out of control is a severe incident in petroleum extraction caused by the failure of conventional well control methods, resulting in the uncontrolled discharge of formation fluids (oil, gas, water).

Refers to a wellbore that has been lined with casing, typically made of steel, to maintain the structural integrity of the well. The casing helps prevent contamination between different geological formations, protects the wellbore from environmental factors, and provides a surface for connecting various well components. The term indicates that the component is specifically designed for use in wells where casing has already been installed, ensuring it can withstand the pressures associated with this environment.

Casing While Drilling (CWD) technology refers to a technique in which casing is run into the wellbore while drilling operations are ongoing. The primary purpose of this method is to run casing directly during drilling, thereby reducing drilling time, minimizing the amount of cement required, and enhancing operational safety. Specifically, CWD technology allows for safe drilling of gas formations without tripping operations, effectively reducing the risk of lost circulation and potential well control issues, while also preventing casing from becoming stuck.

Casing running tools are devices used during drilling and well construction operations to install casing into the borehole. The primary function of these tools is to facilitate the smooth running of the wellhead and the first casing string into the borehole, ensuring wellbore wall stability and secure isolation of the formation.

This petroleum industry term refers to the process of shutting off the open-loop circulation of drilling fluid and switching to a closed, controlled circulation system. This is done to manage downhole pressure and prevent blowouts.

A casing program refers to the design plan specifying the number, type, diameter, and depth of casing strings to be run in a well. It forms the basis of drilling design. An appropriate casing program helps protect the production zone capacity, increase overall drilling speed, and reduce drilling costs.

The conductor casing is the first casing string installed in a wellbore structure. Its primary functions are to protect the surface formation near the wellhead from collapse at the start of drilling, establish drilling mud circulation, guide the advancement of the drill string, and ensure the verticality of the borehole.

The primary functions the installation of wellhead equipment. A casing string refers to a column of casing pipes connected by threads, made from various steel grades, wall thicknesses, and materials, used in oil drilling. Its main functions are to protect and isolate various complex formations, stabilize the wellbore wall, establish oil and gas channels, and facilitate wellhead equipment installation.

A casing shoe is a specialized attachment installed at the bottom of a casing string or liner during drilling operations. It provides protection to the wellbore and surrounding formation, preventing loose material from entering and ensuring a stable drilling environment. Casing shoes also guide the casing string and prevent it from snagging on irregularities.

A "centralizer" is a device used to ensure that something is positioned in the center, or at the middle, of a given space or area. In the context of well drilling and cementing, a centralizer is a mechanical device that keeps the casing centered in the wellbore, preventing it from touching the sides. This ensures a uniform annular space for cementing, which is crucial for a strong and effective seal.

A cement baffle collar is a tool used in cementing operations, particularly in oil and gas well drilling, to assist in isolating different sections of the wellbore for multi-stage cementing. It serves as a landing point for shut-off plugs, which are used to seal off specific areas within the casing string, allowing for controlled cement displacement in multiple stages.

A cementing basket, also known as a float shoe basket or centralizing cement basket, is a mechanical device used in well cementing to protect weak formations from the hydrostatic pressure exerted by the cement column. It's typically installed on casing, tubing, or liner strings above the weak formation.

Cementing plugs are rubber plugs used during cementing operations, primarily for isolating cement slurry, cleaning the casing wall, and preventing cement slurry contamination. Cementing plugs are classified as top and bottom plugs and are typically used as a set. The upper rubber plug is used to isolate the upper cement slurry from the drilling mud, preventing cement slurry contamination and displacing the cement slurry into the annulus. The lower rubber plug is used to clean the wellbore wall, prevent cement slurry contamination, and, after bumping, rupture the rubber membrane to establish circulation.

Refers to the various pressures distributed on the outer edge of the casing, including formation pressure, wellbore wall pressure, and additional loads.

Casing strength refers to the total capacity of the casing to withstand external loads, mainly including three aspects: collapse resistance, internal pressure resistance, and tensile strength.

This is the magnitude of stress at which the casing fails under external collapse pressure.

A casing tong is a tool used for lifting casing and other tubular equipment. It features a simple, safe, and reliable structure, and is widely used in the petroleum, natural gas, cement, and construction industries.

A tool used in petroleum and natural gas drilling operations, primarily for hoisting and lowering casing. It is an essential piece of equipment in drilling operations, playing a critical role especially during casing running and pulling.

A casing spider is a tool used in oilfield drilling and well servicing to grip and suspend casing (steel pipes used to line the wellbore). It can be used to lift and lower the casing string into or out of the well, or to hold it in place on the rig floor. Spiders are essentially a type of elevator or rig floor tool that grips and supports the casing.

Refers to the device installed at the top of the casing during cementing operations. Its primary function is to connect the casing and surface manifold. The connect head enables operations such as circulation, spacer injection, cement slurry injection, rubber plug release, and displacement. It serves as the central hub of the surface manifold and wellhead during cementing operations.

A consistometer is an instrument used to measure the consistency of materials, primarily for testing the flowability of mortar, cement slurry, and similar substances.

Cementing method refers to the process in oil and gas well cementing operations where cement slurry is pumped through the casing into the well to fill the annulus between the casing and the wellbore wall, thereby strengthening the borehole and isolating different formations.

Cement channeling in well cementing refers to a situation where cement slurry flows preferentially along a path with lower resistance, leaving gaps or voids between the cement and the casing or borehole wall. This can occur due to various factors, including inadequate mud displacement or the presence of obstructions that cause the cement to bypass certain areas.

Center for well refers to the process of ensuring that the center of the wellhead assembly coincides with the centerline of the wellbore during installation or maintenance of well equipment. Specifically, center for well is performed to ensure the proper operation and extended service life of well equipment, and to prevent equipment wear and failure caused by misalignment.

In drilling, it refers to a thin cable used to move small parts or provide tension for threaded connections.

Compound logging refers to a comprehensive logging operation in petroleum drilling, in which circulating drilling fluid serves as the carrier for data acquisition. The compound logging unit records changes in geological, oil and gas, pressure, and rock physical property data in the drilling fluid as the depth increases.

Coring footage refers to the length or depth of a rock or concrete core sample extracted during a drilling process. It's a measure of how much material has been successfully removed and retrieved. This footage is crucial for various applications, including geological exploration, construction, and infrastructure projects.

Combination string refers to a drill string composed of drill pipes with different sizes, wall thicknesses, or steel grades. Specifically, a combination string can be assembled using drill pipes of different sizes (larger on top, smaller below), different wall thicknesses (thicker on top, thinner below), or different steel grades (higher grade on top, lower grade below). This design meets strength requirements while reducing the weight of the drill string, enabling deeper drilling under a given rig load.

A key operational fluid in petroleum and natural gas extraction, specifically referring to all fluids that directly contact the production formation (oil and gas reservoir) from the time the reservoir is penetrated until the well is brought into production. Its core function is to optimize fluid performance, reduce damage to the oil and gas reservoir, and clear formation channels to maximize productivity.

Cuttings are waste materials generated during drilling operations, primarily including drilling fluid, rock cuttings, and drilling mud. Cuttings are formed as a result of the interaction between the drill bit and rock during drilling, breaking the rock into small particles that mix with the drilling fluid to form cuttings. The composition and properties of cuttings may vary depending on geological conditions and drilling methods.

A cluster well or multiple well refers to drilling multiple directional wells (or horizontal wells) from a single well site or platform, with wellheads concentrated in one area and well bottoms extending to formation targets in different directions.

Coring is one method of collecting rock and sediment samples for geological research. A coring drill bit is designed with a central opening, around which the drill bit cuts the borehole. The core samples enter this hole, into a special chamber – a coring barrel, as the coring bit advances and then the sample is returned to the ship by wire.

A core is a cylindrical rock sample obtained from underground using a coring bit and other coring tools, primarily used for studying geological structures, resource exploration, and geoscience.

Coring tools are devices used during drilling operations to collect subsurface rock and mineral samples. Their primary function is to extract rock and mineral samples from underground during drilling, providing accurate and reliable subsurface geological data. Coring tools are available in a variety of designs and types to meet sampling requirements under different geological conditions.

A core barrel is a drilling tool used to extract cylindrical samples of rock or other materials. It's essentially a hollow tube with a cutting bit attached, which rotates to create a cylindrical core within the barrel. The core barrel then allows the sample to be retrieved for analysis or other purposes.

Core bit refers to the tool used in petroleum drilling to cut and retrieve cores, commonly known as a core bit (in general core drilling, it is referred to as a drill bit or core bit). Its primary function is to retrieve core samples from underground formations for geological analysis and research.

A large-diameter pipe used to stabilize the wall of petroleum and natural gas wells or boreholes. Casing is inserted into the borehole and secured with cement to isolate formations, prevent borehole collapse, and ensure the circulation of drilling mud for efficient drilling and extraction.

Drilling fluid displacement is the process of replacing one drilling fluid with another, typically to transition between different phases of drilling or well completion. This involves carefully removing the existing fluid and introducing a new one, often using spacer fluids to ensure compatibility and prevent issues.

The Driller's Method is a well control technique used during oil and gas drilling to handle situations where a well kick (sudden influx of fluids) occurs. It's a two-circulation method that involves initially circulating the kick out of the well with the original mud weight, followed by a second circulation to kill the well using a heavier, kill-weight mud.

A drift diameter gauge is a specialized tool used to check the drift diameter of downhole casing in oil wells. It primarily consists of a connector and a cylindrical body. The lower part of the connector is threaded to attach to the cylinder, while the lower section of the cylinder is designed to be slightly thinner. This allows the cylinder to deform when the inner diameter of the casing at a deformed section is smaller than the outer diameter of the drift diameter gauge. As a result, it helps assess the extent of casing deformation, cushions impact forces, reduces the risk of the drift diameter gauge getting stuck, and facilitates the retrieval of the drill string‌.

Drilling liner cementing is a process in well drilling where a liner, a casing string suspended from another casing, is cemented in place. This process creates a seal between the liner and the surrounding formation, providing support and preventing fluid migration. A liner is often used to extend the drilling depth or address issues with existing casing.

A drilling liner hanger ‌is a specialized tool used to suspend the liner at the bottom of the previous casing string, primarily for cementing operations. Drilling liner hangers are divided into mechanical and hydraulic types; both use slips to suspend the liner from the upper casing.

Drilling equipment refers to critical mechanical systems used in the extraction of petroleum, natural gas, and other resources, typically comprising multiple functional systems that work together to perform drilling operations. These systems include the drilling rig, drilling floor, pump room, well control equipment, and solids control equipment.

A dead line anchor is a crucial component in drilling rigs, primarily used to securely anchor the dead line, which is the non-moving end of the drilling line. It provides a stable, fixed point for the drill line, ensuring it remains taut and secure during drilling operations. The anchor helps maintain consistent tension, preventing slack, and also bears the substantial loads from the drill string, preventing stress on other rig components.

In the context of oil and gas drilling, a "drill rope" or "drill line" is a strong, multi-threaded wire rope used to lift and lower the heavy drill string (the pipes and tools used to drill the well) into and out of the wellbore. This rope is typically reeved (threaded) between the crown block and traveling block of the drilling rig, allowing for controlled movement of the drill string.

Drilling fluid logging is a well logging method used during drilling operations, which involves real-time monitoring and evaluation of subsurface geological conditions by analyzing cuttings, oil and gas shows, and other data carried by the drilling fluid. Drilling fluid performs multiple functions during drilling operations, including carrying cuttings, balancing formation pressure, cooling and lubricating the drill string, stabilizing the wellbore wall, transmitting hydraulic power, suspending cuttings, forming a mud cake, protecting the oil and gas reservoir, and monitoring downhole information.

Drill pipe and tools accident refers to various faults and damage events occurring to the drill pipe and tools during drilling operations. These incidents typically include drill pipe and tools breakage, stabbing damage, and uncoupling, which can interrupt or affect drilling operations.

Drill string free fall, also known as impact drilling, uses surface hoisting equipment to lift the wire rope, raising the drill bit off the well bottom and then dropping it to impact and fracture the rock. Water is continuously injected into the borehole to mix cuttings and mud into drilling mud. A sand bailer is then lowered to remove cuttings, allowing the borehole to deepen progressively.

Drill string not well braked refers to the phenomenon during drilling operations where, due to an ineffective brake system or inexperienced operation, the drill string suddenly slips, resulting in an instantaneous excessive weight on bit. This is typically caused by uneven drilling feed or poor control of weight on bit.

Drill string failure refers to the sudden fracture or detachment of drill string components (such as the drill bit or drill pipe) during drilling operations. This phenomenon usually results in the interruption of drilling operations and requires appropriate remedial measures to restore operations.

During drilling, the phenomenon where the drill string becomes trapped in the wellbore and cannot move freely due to various causes is referred to as drill pipe sticking. The drill string cannot be pulled out of the well, and may also be impossible to lower or rotate; in some cases, circulation of drilling fluid is also not possible. This is a common incident in drilling operations.

The length achieved during drilling, measured in meters. The drilling footage achieved in one work shift (8 hours) is called shift footage; there are also daily footage, monthly footage, yearly footage, etc.; The total depth drilled by a single drill bit is referred to as the bit footage; footage is a workload indicator in drilling or exploration operations and serves as a fundamental item in drilling plans, statistics, accounting, and quotas.

Drilling refers to the engineering operation that uses specialized equipment and technology to drill a cylindrical hole from the surface to connect with underground oil and gas reservoirs or other target formations.

Drilling method refers to the specific operational procedures and technical means of using mechanical equipment or manpower to drill a hole from the surface into the formation.

In oil and gas wells, a deep well is defined as a completed well depth of 4,500–6,000 meters, while a depth exceeding 6,000 meters is classified as an ultra-deep well.

Drilling quality refers to the overall performance of three main aspects in drilling engineering: borehole quality, core recovery quality, and cementing quality.

This term denotes the collective name for all tools and equipment used during oil and gas well drilling operations. These tools are primarily used for boring and drilling, facilitating the completion of oil and gas well borehole drilling. The specific components of the drill string include the Kelly, drill pipe, drill collar, connector, stabilizer, hole opener, shock absorber, etc.

A drill stem, also known as a drill string, is the assembly of equipment used in well drilling to transmit power and rotate the drill bit. It essentially connects the drilling rig to the drill bit at the bottom of the well.

Drilling fluid is a general term for various circulating fluids used during drilling operations to meet operational requirements through multiple functions. It is also known as borehole flushing fluid or drilling mud.

A directional well is a drilling technique characterized by deviating from the vertical line at a predetermined angle and following a planned trajectory to reach a specific subsurface target formation.

Refers to two wells constructed in close proximity using the same drilling rig simultaneously. These two wells are operated alternately by the drilling rig. For example, when tripping out in one well, the withdrawn drill string can be directly run into the other well for drilling operations. When drilling one well, another well can be used for deviation survey or electric logging.

Deflecting or building angle refers to the process in drilling operations where specific tools and methods are used to intentionally deviate the borehole in a certain direction and angle. Specifically, deflecting or building angle is achieved by using deflection tools such as kick-off subs, bent subs, bent motors, and rotary steerable systems, which cause the drill bit to cut asymmetrically and generate lateral force during drilling, thereby changing the direction and angle of the borehole.

A drill collar is a thick-walled, tubular component used in drilling operations, typically positioned directly above the drill bit. It's designed to provide weight on the bit, which is the downward force needed to penetrate the earth and advance the drill bit.

A drill pipe is a robust, hollow steel tube used in drilling operations, particularly in oil and gas exploration, to transmit torque, lift, and drilling fluid to the drill bit. It's essentially a critical component of the drilling string, connecting the drilling rig to the bit at the bottom of the well.

An Electric Submersible Pump (ESP) is a type of artificial lift system used in oil and gas production to lift fluids from deep within wells. It consists of a motor and a multistage centrifugal pump, both submerged in the well, and uses electricity to power the pump and lift the fluids.

Equivalent depth refers to the well depth at which the reduced bedrock stress in an abnormally high-pressure formation is equal to the bedrock stress under normal pressure. Specifically, when the porosity of the rock is high, formation pressure increases while bedrock stress decreases. Equivalent depth is the well depth at which the reduced bedrock stress is equal to the bedrock stress under normal pressure in such conditions. In oil and gas exploration, the Equivalent Depth Method is a quantitative technique for evaluating abnormal formation pressure. When formation pressure is relatively low (pressure coefficient < 1.4), the results from the Eaton Method and the Ratio Method are more accurate. When the formation pressure is high (pressure coefficient > 1.4), the Equivalent Depth Method is recommended. These methods are all based on the normal compaction curve. Appropriate compaction parameters should be selected to establish the normal compaction curve during application.

This is a specialized well control method in which, while maintaining a certain wellhead pressure to ensure formation stability, the gas that has invaded the well is allowed to rise and expand to the wellhead. Heavy drilling fluid is then intermittently pumped in to displace the gas until the well is completely filled with drilling fluid and pressure balance is restored.

Expansion cement is a hydraulic cementitious material produced by finely grinding Portland cement clinker with an appropriate amount of gypsum and an expanding agent. It offers excellent impermeability, compressive strength, and crack resistance.

A downhole tool used to cut tubing or similar tubulars that have become stuck in the wellbore. The external cutter slips over the fish or tubing to be cut.

A float collar is a drillable check valve installed inside the upper coupling of the casing shoe. It is primarily used to guide the casing string smoothly into the well, adjust the buoyancy of the casing string during running, and prevent cement slurry from flowing back into the casing, thereby ensuring cementing quality.

A float shoe is a device that combines a guide shoe, casing shoe, and valve body into a single unit. It is primarily used in petroleum engineering to function as a support ring and back pressure valve.

Fiber cement is a type of engineered building material composed of cement, fibers, and other auxiliary materials processed through specific manufacturing techniques. It is known for its high strength, excellent crack resistance, and superior durability.

The final open hole completion refers to the process during drilling in which the drill bit is not changed, the oil reservoir is drilled through directly to the designed well depth, then technical casing is run to near the top boundary of the oil reservoir, and cement is injected for cementing. The main feature of this method is that the oil reservoir remains fully exposed, resulting in no additional flow resistance, higher productivity, and a high degree of completion. However, this method cannot address the impact of wellbore wall collapse or sand production from the reservoir on well performance, nor does it allow for selective acidizing or fracturing operations.

Fish refers to objects lost downhole, specifically drill string left in the well due to accidents.

In petroleum drilling, it refers to the operation of retrieving downhole objects using appropriate tools and methods.

A fishing tool used during drilling operations, primarily designed to retrieve heavy iron filings or metal debris that cannot be removed from the borehole through normal drilling mud circulation. Its operating principle is to utilize the sudden decrease in drilling fluid velocity at the cup mouth to create a vortex, reducing the carrying capacity of the drilling fluid. This causes heavier debris to settle into the cup, allowing it to be retrieved when pulling out of the hole.

Finishing drilling is a technical term in the field of oil drilling, referring to the process of terminating drilling operations after reaching the predetermined depth or achieving the intended construction objectives.

An expression of the concentration of hydrogen ions present in a solution.

A synthetic resin possessing the ability to attract and to hold charged particles.

Gas channeling refers to the process in which gas that has entered the wellbore, due to its low density, slowly migrates upward to the wellhead. This phenomenon typically occurs after a gas column invades the well bottom. If the well remains shut in for an extended period, the pressure inside the well becomes unstable. Although the gas pressure is high, its low density causes it to slowly migrate upward and accumulate at the wellhead. Gas channeling is a phenomenon that requires special attention during drilling, as it may lead to serious issues like blowouts. During drilling operations, appropriate measures must be taken to prevent and manage gas channeling to ensure safe and efficient operations.

A guiding shoe is a conical device attached to the lowermost end of the casing string. Its primary function is to guide the casing smoothly to the well bottom and prevent the casing shoe from scraping or penetrating the wellbore wall. The guiding shoe plays a critical role in drilling operations, especially in boreholes where severe sticking problems are anticipated, such as horizontal wells and extended reach wells. Using a guiding shoe can significantly improve operational efficiency.

This is a completion method in which a specified size and quantity of gravel is packed between the liner and the wellbore wall, primarily for sand control. Specifically, this method involves packing gravel in the annulus between the liner and the open hole, or in the annular space between the liner and the casing, to prevent formation sand from entering the wellbore, thereby protecting the wellbore wall and preventing sand production from the oil reservoir.

This is a method that continuously measures the content of combustible gases in the drilling fluid using a gas detector. It is primarily used to identify oil and gas reservoirs, promptly detect hydrocarbon shows, and predict blowouts. Gas logging is performed during drilling operations. By analyzing the content and composition of hydrocarbon gases in the drilling fluid, it is possible to determine whether an oil and gas reservoir has been encountered underground.

This refers to the method of directly closing the wellhead blowout preventer when the choke line is closed. Specifically, hard closing refers to the operation of directly closing the blowout preventer without opening any fluid channels when a kick or influx is detected.

The high-pressure squeezing method is a technique that applies high pressure to fracture the formation, thereby forcing cement slurry into the formation. Specifically, the high-pressure squeezing method increases the well bottom operation pressure beyond the formation fracture pressure, causing the formation at or near the perforation to fracture, and then forces cement slurry into the fractures. This method is primarily used for sealing water layers and for remedial cement squeezing in fractured formations.

High H2S gas well completion refers to a series of specialized technologies and methods used during the completion of natural gas wells with high concentrations of hydrogen sulfide, to ensure the safe and efficient operation of the gas well.

A horizontal well is a drilling technique in which the wellbore trajectory extends horizontally or nearly horizontally within the target formation. The maximum inclination angle is typically ≥86° (close to vertical), and may even exceed 90° to form an 'upward' structure. Compared with vertical wells and directional wells (non-vertical but with a specific trajectory), the core difference of horizontal wells lies in the design of the horizontal section length and angle.

Heavy weight drill pipe is a downhole tool used to add weight during drilling operations, typically installed between the drill pipe and the drill collar ‌‌. Its wall thickness is between that of the drill pipe and the drill collar, allowing it to withstand tensile and compressive loads, prevent sudden changes in the drill string cross-sectional modulus, and reduce drill pipe fatigue failure.

Installing a wellhead in the oil and gas industry involves setting up the equipment at the top of a well to control the flow of fluids and provide a platform for various operations like drilling, production, and maintenance. It's a critical process that ensures the well's structural integrity, prevents well collapse, and allows for safe and controlled access to the wellbore.

Intermediate casing string refers to casing used during drilling operations to address complex formations, such as high-pressure zones, loss zones, and unstable formations. It is positioned between the surface casing and the casing, with the primary function of protecting and isolating complex formations to ensure smooth drilling operations.

The inner pipe cementing method is a specialized cementing technique primarily used for large-diameter casing cementing. This method involves inserting a small-diameter drill pipe, equipped with a float collar plug at the lower end, into the plug-type float collar (or plug-type float shoe) of the casing to establish circulation with the annulus. Cement slurry is then pumped by a cement truck through the drill pipe into the annulus outside the casing. The main advantages include reducing the mixing of cement slurry with drilling fluid inside the casing, shortening the time required to displace drilling fluid, and enabling earlier return of the cement slurry, thereby minimizing issues caused by excessive additional cement volume.

The initial open hole completion involves running technical casing and injecting cement for cementing after the drill bit reaches near the top boundary of the oil reservoir. After the cement slurry returns to the predetermined design height, a smaller diameter drill bit is run through the technical casing to drill through the cement plug and into the oil and gas reservoir to the designed well depth for completion.

A Reverse Circulating Junk Basket (RCJB) is a specialized fishing tool used in oil and gas well drilling to remove small debris and junk from the wellbore. It utilizes reverse circulation of drilling fluid to efficiently collect and transport junk items to the surface. The tool is designed to retrieve items like bit cones, slips, hand tools, and other small pieces of junk that may have been lost or accumulated in the wellbore.

During drilling, if a high-permeability formation is encountered and the bottom hole pressure is lower than the formation pressure, formation fluids will enter the borehole. When the volume of fluid entering the borehole reaches a certain level, it is referred to as a well kick.

In the oil and gas industry, "kill a well" refers to the process of stopping a well from flowing, typically by injecting fluid of a higher density than the formation fluids to overcome the pressure. This is done to control blowouts or prevent further flow when the well is not in use.

The killing well method refers to the technical procedure during drilling operations in which fluid of appropriate density is injected into the wellbore to control formation pressure, prevent blowout or influx, and restore pressure equilibrium within the well.

In the petroleum industry, this refers to a flexible connecting component primarily used in drilling or pipeline systems to provide flexible connections.

The Kelly bushing is a component mounted on the rotary table during normal drilling operations. It secures the kelly to ensure that the rotary table's power is transmitted to the drill string, driving the drill bit to rotate. Its structure must withstand drilling pressure and torsional loads, serving as the core power transmission component in drilling operations.

Lost circulation materials are used for plugging and waterproofing, primarily to fill and seal various cracks and holes to prevent liquid or gas leakage.

Light weight connect refers to cement materials with relatively low density. The density of this cement typically ranges from 0.42 g/cm³ to 1.6 g/cm³, with the specific density depending on its composition and preparation method. The primary methods for preparing light weight connect involve introducing gas into the cement slurry and adding surfactants to stabilize the foam, thereby reducing the density.

The low-pressure squeeze method refers to applying pressure during cement squeezing that is only sufficient for the cement slurry to dehydrate and form a cement cake in channels and fractures, without fracturing the formation. The key to this method is maintaining the well bottom pressure below the formation fracture pressure. It is typically used to repair well completion cementing defects, address low cement returns, and seal off non-productive oil reservoirs.

The liner completion method is a type of oil and gas well completion technique. Its core operational steps include running a pre-perforated liner into the open hole section, anchoring it to the casing in the oil reservoir using a hanger, sealing the annulus, and enabling oil and gas to flow into the well through the perforations.

Layout refers to leveling the site based on the designated drilling location and rationally arranging the relative positions of the drilling rig and auxiliary equipment such as power units, water pumps, mud tanks, mud pits, and derricks. The objective is to facilitate construction operations and ensure safety.

Levelling is a critical preparatory operation prior to drilling installation, tasked with preparing an adequately sized work site at the designated well location. Specifically, levelling must comply with design requirements, ensure the well site is flat with a 3%–4% slope for effective drainage, and utilize the terrain as much as possible so that liquids in mud tanks, water tanks, and similar containers can flow by gravity to their points of use. The derrick and equipment foundations should not be located on fill areas to ensure both economic efficiency and operational safety.

Logging is a key technology in oil and gas exploration and development, involving the collection and analysis of real-time geological and engineering data during drilling to obtain subsurface formation information and hydrocarbon indications. Its core functions include establishing geological profiles, identifying oil and gas reservoirs, and optimizing drilling engineering decisions.

Lithologic logging refers to the process of detailed observation, measurement, and analysis of lithologic samples obtained during drilling.

Lead stamp is a tool used to determine the position of downhole fish and the condition of the fracture. It is made by cutting a section of casing to the required size, filling the cut portion with lead or paraffin wax, and leaving a water port for circulating drilling fluid. Lower the lead stamp into the well and apply appropriate pressure to the top of the dropped object to create an impression. After retrieving the impression tool, the impression on the lead end can be used to determine the condition and position of the drill string in the well.

The left hand fishing spear, also known as a left-hand coupling, is a ZDM-type drill string tool. It is a specialized tool used for left-hand operations on stuck drill string downhole. During left-hand fishing operations, this tool allows the drill string to be operated without a safety joint, enabling safe back-off through surface manipulation.

A magnetic locator sub is a short casing section installed on the casing string near the production zone, used to calibrate perforation depth. This sub is commonly used in petroleum and natural gas drilling to ensure the accuracy of perforation operations.

The mobility of slurry refers to its ability to flow and uniformly and densely fill the formwork under its own weight or mechanical vibration. Mobility reflects the consistency of the cement slurry and is a key indicator for evaluating its flowability.

Multi-plezone completion cementing is a specialized completion method used in multi-reservoir wells when single-tubing or conventional completion methods are not economical. This process involves running up to four or five drill strings in a single borehole (with tubing serving as casing). Typically, the longest string is run first, set in place, and drilling fluid is circulated before running the next longest string. This sequence continues until all strings are installed. Cement is then injected, usually with cement slurry pumped simultaneously through the two longest strings. The remaining strings should be pressurized to 7.0–14.0 MPa during cementing to prevent leakage, thermal bending, or collapse. If injecting cement slurry with two of the longest drill strings does not allow return to the area around the shortest drill string, the entire drill string assembly may be used for cement injection.

A mud manifold is equipment used to collect drilling mud discharged from two mud pumps and deliver it to the well and mud tank. It primarily consists of multiple intersecting pipelines and efficiently completes fluid transportation and control through the coordinated operation of various devices. Mud manifolds typically use connections such as unions, threads, welding, and flanges.

Mill shoe is a petroleum term referring to a tool used in drilling operations. The primary function of the mill shoe is to protect the drill bit during drilling, preventing damage from downhole rocks or obstructions. It is typically installed below the drill bit, and its specially designed teeth help the bit penetrate rock formations more effectively while reducing bit wear.

Mouse hole is a drilling engineering term used for the temporary storage of single drill pipes or for connecting drill string components. It is located directly in front of the wellhead and is used for pre-positioning and connecting single drill pipes to accelerate the single pipe connection operation.

A multibore well is an engineering term referring to drilling two or more branch boreholes from a main borehole in predetermined directions as designed. A multibore well is also referred to as a branch well, characterized by having two or more well bottoms beneath a single wellhead.

Measurement While Drilling (MWD) is a real-time monitoring technology that continuously measures downhole parameters during the drilling process. It acquires formation information, drilling parameters, and wellbore trajectory data through sensors, and transmits these data to the surface system using methods such as mud pulse and electromagnetic waves.

The Motor Control Center, also known as the Motor Control Center or MCC, centrally manages power distribution and instrumentation equipment, integrating various motors Control unit、Feeder line Coupling unit, Distribution transformer、Lighting distribution panel, interlock relays, and metering devices into a single integrated enclosure, managed by a common Enclosed busbar Power supply.

NPT refers to periods when equipment is not engaged in productive operations.

A non-magnetic drill collar is a type of drill collar tool manufactured primarily from low-carbon, high-chromium manganese alloy steel. Its key features are low magnetic permeability (relative permeability μr≤1.010) and high mechanical strength.

OH in drilling denotes 'Open Hole.' During drilling operations, the hole created after the drill bit penetrates the formation is referred to as an 'open hole well.' This well type does not have casing or cementing and is directly exposed to the formation.

Oil country tubular goods are fundamental to the petroleum industry. Casing, tubing, and drill string components (drill pipe, drill collar, kelly, etc.) are collectively referred to as oil well pipes.

Overflow refers to the phenomenon in which a liquid or fluid exceeds the capacity of a container or system and spills out.

An out of control for blowout is a severe accident in oil extraction caused by the failure of conventional well control methods, characterized by the uncontrolled eruption of formation fluids (oil, gas, or water).

Oil well connecting is a specialized cement used for cementing operations in oil and gas wells. Its primary function is to bond the casing to the surrounding formation, isolate oil, gas, and water zones within the formation to prevent crossflow, and thereby establish a well-isolated flow channel from the reservoir to the surface.

The open hole completion refers to running casing and performing cementing after drilling to the top of the oil and gas reservoir, then continuing to drill through the reservoir with a smaller drill bit to keep the wellbore wall of the reservoir section fully exposed, or using a simple screen for isolation. The core feature is that casing and cementing are not performed in the target formation section, allowing the oil and gas reservoir to be directly connected to the well bottom, thereby maximizing flow area and flow efficiency.

An overshot is a tool used in downhole operations, primarily for retrieving objects that have fallen into the well. There are various types of overshots, each with specific applications and technical characteristics.

In drilling, POOH refers to the operation of pulling the drill string out of the borehole. This is a critical step in drilling operations, typically performed to change the drill bit, conduct logging, address downhole issues, or complete drilling tasks.

It is made by using polycrystalline diamond (thin disc-shaped) to form small cutting elements that are mounted or sintered onto drill bit body. Suitable for soft to medium-hard formations.

Production casing, also known as casing, refers to the final string of casing run after the target formation has been reached in an oil and gas well. Its primary function is to establish a secure channel for the production zone, protect the wellbore wall, and meet the requirements for zonal production, testing, and stimulation operations. Production casing extends from the wellhead down past the penetrated oil and gas reservoir, ensuring that oil and gas can flow smoothly from the well bottom to the surface, while also preventing oil and gas from leaking into other low-pressure formations.

Preceding stress refers to the compressive stress applied to a structure or component prior to the application of external loads. This technique improves structural performance, counteracts tensile stresses induced by loading, prevents damage, and delays crack formation. It is widely utilized in concrete structures.

The perforated completion creates channels by perforating the casing and cement sheath, enabling oil and gas to flow from the reservoir into the wellbore while maintaining support for the wellbore wall structure.

Permanent completion refers to a series of engineering measures implemented after oil and gas well drilling is completed, establishing connection between the wellbore and the oil and gas reservoir and providing a channel for oil and gas inflow into the well. These measures include running production casing, cementing, perforation, or acid fracturing. The purpose of the permanent completion is to ensure long-term stable production of the oil and gas well.

The permanent completion with single packer is a completion technique that utilizes a permanent packer to create a seal between the tubing and casing, preventing fluid from entering the annular space. This completion method is typically used in high-pressure/high-temperature oil and gas production wells. Featuring simplicity, stability, and reliability, it can adapt to the reservoir's life cycle, and minimizes drilling rig occupation time.

Permanent completion with packer is a well completion technique in petroleum engineering, primarily used for the completion of oil and gas wells. The basic principle involves using a perforating gun to create channels in the casing and cement sheath, enabling oil and gas to flow from the reservoir into the wellbore. The packer supports the wellbore wall structure to ensure wellbore stability.

Perforating with negative pressure refers to perforating the oil and gas reservoir when the completion fluid column pressure in the wellbore is lower than the formation pressure. Perforating with negative pressure not only prevents perforating fluid from invading the formation, but also removes debris and compacted layers within and around the perforation tunnel, thereby establishing a clean and unobstructed oil and gas flow channel around the wellbore.

Perforating through tubing refers to perforation operations performed in the well using a negative pressure differential. Specifically, the perforating gun is connected to a cable and conveyed through the tubing to the formation for precise alignment. The perforating gun is run through the wellhead blowout preventer, Christmas tree, and tubing into the casing using an oilfield cable. Depth correction is then performed within the casing to perforate the target formation.

Perforated pipe completion, in the context of well construction, refers to a common method where a well is cased and perforated to provide communication between the reservoir and the wellbore. This method involves lining the well with a casing (or liner), which is then cemented in place to isolate different zones within the reservoir. After cementing, the casing is perforated to allow fluid from the reservoir to flow into the well.

Preliminary work for spudding refers to all preparatory activities conducted before drilling an oil and gas well, collectively known as preliminary engineering. Preliminary engineering comprises multiple stages and specific tasks to ensure that drilling conditions are met before actual drilling operations can begin.

Penetration rate logging is a method that records the footage drilled per unit time during drilling operations.

A packed hole assembly refers to a section of the drill string above the drill bit with a diameter equal to or only slightly smaller than the borehole, resulting in minimal clearance. The primary purpose of this design is to reduce the clearance between the drill string and the wellbore wall, thereby minimizing friction and wear during drilling operations and enhancing drilling efficiency.

The pendulum assembly is an anti-deviation drill string assembly used in petroleum drilling. Its core design is based on the 'pendulum effect' in physics, enabling automatic deviation correction by adjusting the drill string structure.

The positive displacement motor drill tool (abbreviated as PDM drill) is a volumetric downhole power drilling tool powered by drilling fluid, which converts fluid pressure into mechanical energy. Drilling mud pumped by the mud pump flows through the bypass valve into the motor, where the pressure differential of the drilling fluid drives the rotor to rotate, transmitting speed and torque to the drill bit to perform drilling operations.

A pit volume totalizer is a device used to measure and record the volume of drilling mud in the mud pit. It is typically installed at the outlet of the mud pit and calculates the volume of drilling mud by measuring its flow rate and velocity. This equipment is essential in oil and gas field drilling operations, as it enables engineers to accurately monitor drilling mud usage, ensuring the safety and efficiency of drilling operations.

In the drilling industry, the mechanical rate of penetration (ROP), also known as penetration rate or drilling rate, is the speed at which the drill bit breaks the underlying rock to deepen the borehole.

Running casing refers to the process of connecting sections of steel pipe (casing) together and lowering them into a borehole, typically in oil and gas well construction. This casing serves to protect the wellbore and isolate different geological formations.

In the context of wellbore operations, releasing tools are devices that allow for the disconnection and retrieval of tools that may become stuck.

The releasing stuck tamping is a technical approach used to address downhole stuck pipe issues. The specific procedure involves attaching a jar above the fishing tool. Once the fish is engaged, the jar is operated to generate a significant upward impact force, thereby freeing the stuck pipe.

A reamer is a tool used in petroleum drilling to enlarge the borehole, also referred to as an enlarger or back reamer. Structural types include fixed and downhole expandable designs, with most operating principles utilizing drilling fluid pressure differentials to actuate the outward movement of the blades. Reamers are widely used for borehole enlargement in salt and gypsum formations to counteract formation creep and enhance cementing quality.

Reaming is a specialized term in petroleum drilling, referring to the operation of moving a drill bit of the same diameter as the original borehole up and down and rotating within the well to smooth and maintain the roundness of the borehole.

A rat hole refers to a small hole on the drilling platform used for temporarily placing the Kelly (with swivel), constructed with casing (rat hole casing) inserted into the ground at an angle. A similar structure, the 'mouse hole,' is used for placing single drill pipes.

In the petroleum industry, a relief well is a directional well drilled from the surface (or seabed) at a safe distance from the blowout well after a blowout has occurred, for the purpose of well control and rescue operations. This type of well is controlled using directional drilling, approaching the blowout well at the well bottom (oil and gas reservoir) to establish connection. Drilling mud can be injected into the blowout well to control the blowout, or cement can be injected to permanently seal the blowout well.

The rotary steerable system (RSS) is a guided drilling system that provides real-time steering capability while the drill string is rotating. It is a major advancement in directional drilling technology since the 1990s, featuring low friction and torque resistance, high rate of penetration, and reduced costs.

Surge pressure, also known as water hammer, is a sudden, short-lived increase in pressure within a pipe system caused by a change in the velocity of the fluid flowing through it. This can happen when a valve is suddenly closed or a pump is rapidly stopped. The sudden change in fluid momentum leads to a pressure wave that can cause significant stress on the piping system, potentially leading to damage.

Swabbing pressure is the reduction in hydrostatic pressure in a wellbore that occurs when a drill string, casing, or other tool is quickly pulled upward. This pressure drop can create a situation where the formation pressure exceeds the wellbore pressure, potentially leading to a "kick" (influx of formation fluids).

Soft closing refers to the procedure during kick detection in which the choke line is first opened, the blowout preventer is then closed, and finally the choke valve is closed.

Surface casing is the outermost casing in the casing program of an oil and gas well. After drilling the wellbore to the bedrock below the surface soil layer, or to a specified depth, the surface casing is run.

Slurry density refers to the specific gravity of water and cement in the cement slurry at a given temperature, typically expressed in kilograms per cubic meter (kg/m³) or pounds per gallon (lb/gal).

Refers to the volume of filtrate that passes through the filter medium and the mud cake formed during the filtration test of drilling fluid. A lower filtration loss of drilling fluid indicates the easier formation of a low-permeability, flexible, thin, and dense filter cake, which is advantageous for stabilizing the wellbore wall and protecting the oil and gas reservoir.

Spacer fluid is primarily used in cementing operations in petroleum engineering. Its core function is to separate the drilling fluid from the cement slurry, preventing direct contact and subsequent performance degradation.

The Squeeze Packer Method is a technique in wellbore cementing where a specialized packer, or squeeze tool, is used to isolate a section of the wellbore and apply pressure to inject cement into a specific zone or area. This method is used to repair or seal leaks in the wellbore, isolate specific zones, or improve the overall cement sheath around the well casing.

Single pipe permanent completion without packer refers to a method in oil and gas well completion where a packer is not used, and single-pipe permanent completion is achieved by alternative means. This method is typically suitable for wells with stable conditions, where it is unnecessary to use a packer to isolate different reservoirs.

String up refers to the process of threading wire rope through various sheaves in the drilling equipment and securing it to the drawworks and the dead line anchor. This is one of the primary tasks during drilling equipment installation.

In the oil and gas industry, "skidding a rig" means moving a drilling rig from one well location to another, typically within a well pad or on a fixed offshore platform. This is done by sliding the rig along a series of tracks or rails, often using hydraulic cylinders, with little to no dismantling of the equipment.

Safety line refers to the rope or chain used to connect and secure the tong, a type of mechanical tool commonly used in drilling operations. Specifically, safety line typically uses a 19 mm diameter steel wire rope, which is connected and secured to the derrick leg or a dedicated tail stake. The length of the tong inner and outer tongs line must be appropriate, with no broken wires or corrosion. Each end should be fastened with two rope clips matching the rope diameter to ensure secure fixation.

The surface bumper jar is a tool used in drilling operations, primarily designed to resolve stuck drill string issues in the well. It does not require the tool to be run into the well and is operated on the drilling floor, making it highly convenient to use. The surface bumper jar allows adjustment of the jarring force to accommodate different freeing requirements, and enables jarring and rotation operations while circulating drilling mud. It features a simple structure and is easy to maintain.

The sticking point instrument is a specialized device for measuring the location of stuck points, offering higher measurement accuracy than traditional stretching methods. The instrument consists of a surface unit and a downhole instrument. Surface instruments include depth recorders, drill string elongation direct-reading meters and recorders, torque direct-reading meters and recorders, as well as various auxiliary instruments and detonating devices. Downhole instruments include heavy-weight drill pipe, jar, and the measurement section. The measurement section has two contact points with the drill string, with a distance of 1.32 meters between them. When the instrument reaches the sticking point, there is no elongation change in the drill string, indicating that the sticking point has been reached.

A vertical well refers to a well with a designed trajectory as a vertical line, meaning the wellbore trajectory is generally vertical. This is a term used in drilling engineering and is contrasted with a directional well. A vertical well is characterized by a borehole axis that is a vertical line, with the designed target area within the target formation and the wellhead at the surface aligned on the same vertical line.

Generally refers to drilling operations where the well (borehole) depth exceeds 6,000 to 8,000 meters.

Sidetracking is a critical process in petroleum engineering, primarily used to repair blowout wells, enhance recovery, or adjust the wellbore trajectory. The core of this technique is to create a window (or mill a section) at a specific location in the original wellbore, drill a new branch borehole, and complete subsequent operations like cementing.

Starting window on casing uses a milling cone to uniformly grind and mill the casing and whipstock along the inclined surface of the whipstock, creating a smooth, elongated window in the casing to facilitate the smooth running and retrieval of the drill bit, drill string, logging tools, casing, and other equipment during sidetracking operations.

Stabilizer is a tool used to stabilize the downhole drill string and prevent wellbore deviation, typically connected to a section of drill pipe near the large-diameter drill string. It plays an important role in petroleum, natural gas, and geological exploration drilling projects, ensuring directional stability and preventing well deviation.

A silicon controlled rectifier (SCR) is a power control device based on thyristors, integrated with intelligent digital control circuits. It features high efficiency, noiseless operation, no wear, compact size, and light weight, and is capable of controlling electrical power switching from several kilowatts up to the megawatt level.

Target depth refers to the oil and gas well depth indicated on the daily drilling report.

The top-drive cementing head is a device used in cementing operations, primarily installed at the top of the casing. It connects the casing to the surface manifold and is used for cement injection during cementing.

Tensile resistance is the maximum load-bearing capacity of the casing under tensile force. Specifically, tensile resistance refers to the maximum stress that the material of the casing string can withstand under tension without failure. When determining the tensile strength of casing, both the strength of the casing body and the connection strength of the threaded section must be considered.

The top connecting collar is used in cementing operations to connect the cement head, and is essentially a casing of a specific length.

This refers to the method of using specialized equipment to pump prepared cement slurry into the casing, allowing it to flow up the annular space from the bottom of the casing string to the predetermined well depth, thereby achieving effective zonal isolation between the casing and the wellbore wall in the designated interval.

Two stage cementing is a cementing operation in which cement is injected into the annulus in two stages using stage collars installed on the casing string. The procedure is as follows: install a two-stage cementing collar at the predetermined position on the casing. The collar is equipped with a second-stage cement slurry discharge port, which is initially covered by a sliding sleeve. During first-stage cementing, conventional methods are used to circulate cement slurry from the casing shoe to the designated position in the annular space. When the second-stage cement slurry reaches the two-stage cementing collar, the sliding sleeve is shifted downward, allowing the second-stage cement slurry to be injected into the annular space through the discharge port.

Tubingless completion refers to a method in which tubing is not used during the well completion process. Instead, alternative means are employed to connect the oil and gas reservoir to the wellbore. This method is typically applied in specific completion applications like perforation completion. In perforation well completion, casing is run to the well bottom and cemented in place. A perforating gun is then used to perforate the oil reservoir section, penetrating the casing and cement sheath to create a channel for oil and gas to flow into the well. This completion method does not require tubing and is therefore referred to as a tubingless completion.

Used to loosen debris at the well bottom, allowing the debris to accumulate for retrieval with fishing tools.

The top jar is a tool used in drilling operations, primarily for resolving stuck pipe issues downhole. The top jar releases stuck pipe by generating an upward impact force. It is suitable for resolving sand sticking, brine and mineral crystallization sticking, rubber sticking, packer sticking, and small dropped object sticking in deep wells. It is particularly effective when the derrick load is low and heavy lifting of the drill string is not feasible.

Turbo drilling is a relatively advanced drilling method. Its core principle is to install a turbine directly above the downhole drill bit, utilizing high-velocity circulating fluid to drive the turbine tool, which in turn rotates the drill bit at the well bottom to crush the rock. A turbo drill is typically a hydraulically driven multi-stage turbine installed below the drill string. Drilling fluid is discharged by the surface drilling pump, flows through the interior of the drill string into the turbo drill, impinges on the turbine blades, and drives the drill bit to rotate, enabling drilling operations.

A turbo drill is a power device that converts the kinetic energy of the circulating fluid into mechanical energy, primarily used to drive the drill bit for rotation and drilling. The turbo drill converts the hydraulic energy of the drilling fluid into mechanical energy through the impeller, thereby driving the drill bit to operate.

Tubing is a conduit used to transport crude oil and natural gas from the oil and gas reservoir to the surface after borehole drilling is completed. It is designed to withstand the pressures generated during production.

The top drive system (TDS) is a power unit used in petroleum drilling operations that directly drives the drill string to rotate, replacing the traditional rotary table method. Its core consists of three main components: the power system, guide carriage, and control system. Positioned below the traveling block, it provides clockwise rotational torque to the drill string during the drilling process.

An underground blowout is an uncontrolled flow of fluids from a subsurface zone (a high-pressure zone) to another subsurface zone, or into the wellbore, without reaching the surface. Unlike surface blowouts, which can be visually obvious, underground blowouts may not have any visible signs at the wellhead.

An unbalanced drill collar is a drill collar with part of its mass removed from one side, resulting in an asymmetrical cross-section. Typically, a row of blind holes is drilled on one side, making one side heavier than the other. When the drill string rotates, this uneven mass distribution generates a centrifugal force, resulting in periodic lateral impact forces that drive the drill bit to return to the vertical direction, thereby correcting well deviation.

A vortex sub is a specially designed short casing device installed in the casing string above the casing shoe and below the flow restrictor ring. Its outer wall is equipped with spiral (left-handed) discharge holes. The primary function of the vortex sub is to generate a strong tangential rotational force in the cement slurry entering the annular space outside the pipe through spiral discharge holes on its outer wall, thereby removing drilling fluid from the annular space above the casing shoe and ensuring cementing quality.

This is a tool that achieves vibration damping by controlling the flow of fluid inside the dampener. It reduces vibration by compressing the fluid, thereby protecting the drill bit and drilling rig, and improving drilling efficiency.

A well blowout is a specialized term in the petroleum industry, referring to the uncontrolled and continuous influx of formation fluids (oil, gas, and water) into the wellbore, resulting in ejection to the surface or intrusion into other low-pressure formations.

Well cementing is a core operation in drilling and well completion within petroleum engineering. It involves running casing into the borehole and injecting cement slurry into the annular space between the casing and the wellbore wall. The primary objectives are to isolate formations, support the wellbore wall, and establish oil and gas channels.

A steel wire brush installed on the casing section to be cemented, primarily used to remove mud cake from the wellbore wall. The function of the wall scratcher is to remove residual mud cake from the wellbore wall prior to cementing, ensuring effective bonding between the cement and the formation, thereby improving cementing quality.

Wellhead equipment is the core apparatus installed at the oil and gas wellhead, primarily used to control and regulate production activities in oil, gas, and water wells. Its key functions include sealing the wellhead, suspending the drill string, controlling fluid pressure and direction, and serving as a critical component of well control systems to ensure the safe execution of drilling operations.

In petroleum drilling, a wall hook is a specialized tool used to address drill string retrieval issues. When the drill string is difficult to recover due to leaning against the wellbore wall, the wall hook (also known as a shifting hook) utilizes its semicircular shape and mechanical design to reposition the drill string to the center of the borehole, facilitating subsequent fishing operations. These tools are typically made from thick-walled seamless steel pipe and are classified into two types: one is used in conjunction with fishing tools, while the other is used directly to manipulate the dropped fish.

Well design encompasses the planning and construction of a well, considering various features to achieve specific objectives and manage potential risks. It involves specifying materials, dimensions, and construction methods, and is crucial for various applications, including water supply, oil and gas production, and environmental remediation.

Water-based mud, also known as water-based drilling mud (WBM), is a type of drilling fluid primarily used in well drilling. It consists mainly of water, along with various additives to modify its properties and make it effective for drilling. The additives can include clays like bentonite, polymers, and weighing agents.