47 results about "Lost circulation" patented technology

The invention relates to a drilling fluid leakage layer positioning method. The method comprises the steps that monitoring temperature data of a plurality of monitoring points with different depths set in a shaft are collected; the method comprises the following steps: preliminarily determining a potential leakage layer position of a drilling fluid leakage layer according to monitoring temperature data of a plurality of monitoring points with different depths on the basis of gradient change of a temperature value along with the depth of a shaft, setting a search range for further refining the leakage layer position according to the potential leakage layer position, and setting an initial search position of search; the initial search position is used as a search starting point, and at least two dynamic response indexes of temperature changing along with time are calculated; the search starting point is updated in a set mode, and iteration is executed again until iteration reaches a stop condition; and comparing the dynamic response indexes of at least two temperature changes along with time, which are obtained by each iteration, and based on a set strategy, determining a fine leakage layer position assumed by one iteration as a final drilling fluid leakage layer positioning position.

The application discloses a drilling well leakage monitoring method based on a downhole pressure data stream, which comprises the following steps: installing two measuring short sections in a drilling tool assembly, the measuring short sections being used for measuring the pressure or pressure difference of corresponding well depth positions, and one of the measuring short sections being close to the lower end of the drilling tool; recording drilling basic data for standby; calculating the actual well leakage index at the abnormal point of the pressure factor by using real-time drilling parameters in the drilling process, and comparing the actual well leakage index with a manually set well leakage index critical value to determine whether well leakage occurs; if the actual well leakage index is greater than the well leakage index critical value, it is determined that well leakage occurs, and the well leakage parameters are inferred according to the pressure factor change state, wherein the pressure factor delta is the ratio of the real-time pressure consumption coefficient at the time t to the reference pressure consumption coefficient. The application has good well leakage identification precision, is convenient for real-time monitoring of the well leakage condition, can quickly and roughly determine the well leakage parameters, has good accuracy and reliability, is convenient for making construction measure response quickly, and is favorable for guaranteeing downhole safety.

The invention relates to the technical field of drilling tools, in particular to a strip mine aquifer branch hole while-drilling leaking stoppage and drainage integrated drilling tool which comprises a drill rod mechanism and a drill bit mechanism arranged at the bottom end of the drill rod mechanism, a two-way adjusting mechanism is arranged between the drill rod mechanism and the drill bit mechanism, and double flow channels are formed in the two-way adjusting mechanism. The outer side of the bidirectional adjusting mechanism is fixedly connected with a stabilizing mechanism; through cooperation of the elastic adjusting assembly and the opening and closing adjusting assembly, drilling fluid can be normally conveyed, the plugging agent cannot be discharged, when a leakage layer is detected, the elastic adjusting assembly resets to drive the opening and closing adjusting assembly to move, and the plugging agent can be accurately and directly conveyed to the leakage layer through a discharging groove and an auxiliary chip discharging groove of the stabilizing mechanism; waste of the plugging agent and the drilling fluid is avoided, meanwhile, the plugging agent can be prevented from being in contact with upward-returning mud liquid in the discharging process, and it is ensured that the plugging agent can be concentrated at the leakage position to play a role.

The application discloses a method for determining the position of drilling fluid leakage and calculating leakage parameters, which is used for finding the position of well leakage during drilling, calculating the leakage speed and leakage amount of drilling fluid, and estimating the leakage scale. The application describes the principle that the photoelectric absorption cross section Pe value of barite contained in the drilling fluid is abnormally high compared with other rocks, minerals and fluids, and the leakage position is accurately positioned by the characteristics of the high value of the Pe curve measured by the lithology density logging in the leakage well section, and the leakage speed is predicted by the correlation between the Pe logging value and the instantaneous leakage speed, and the leakage amount is calculated by combining the method of multi-mineral analysis with the actual content of barite in the drilling fluid. The method is simple and easy to operate, and the accuracy is reliable. Compared with the data provided by the field, the error of the leakage speed and the leakage amount calculated by the method is small, and the effect is good.

This application provides a multi-parameter fusion-based intelligent interactive method for intelligent drilling operations in explosion-proof environments. The method includes: obtaining a joint feature sequence dataset containing abnormal pump pressure spikes and continuous torque increases by fusing historical drilling multi-parameter time-series data and formation lithology stratification sequences; processing the joint feature sequence dataset using a long short-term memory network to obtain a predictive model capturing the temporal coupling relationship between pump pressure and torque, as well as the formation response delay effect; updating the drilling parameter control baseline using the torque-pump pressure trend envelope curve data to obtain a sequence of rotary table speed, drilling pressure, and displacement control commands targeting the pump pressure and torque coupling relationship; and feeding back the rotary table speed, drilling pressure, and displacement control command sequences to the drilling control system to obtain the actual pump pressure and torque sequences for the next well section after real-time execution. This application can effectively reduce the probability of complex accidents such as stuck pipe and lost circulation.

The invention relates to a ball basket mechanism and a while-drilling leaking stoppage tool, the ball basket mechanism is located on the lower portion of the while-drilling leaking stoppage tool, a ball valve mechanism is arranged in the ball basket mechanism, and when leaking stoppage operation is not needed, a ball basket center channel is in an unblocked state; when well leakage occurs, a circulating hole of the tool is opened or closed in a ball throwing mode to conduct leaking stoppage operation, and after leaking stoppage operation is finished, thrown balls are intercepted through a ball valve mechanism and then guided into the space between a ball basket and a tool shell through a ball basket mechanism to be stored; a damping mechanism is further arranged in the plugging-while-drilling tool, and the ball valve mechanism intercepts and stores thrown balls under the matching action of the damping mechanism, so that smoothness of a central channel of the ball basket is guaranteed, and further ball throwing or cable descending operation of an underground tool below the plugging-while-drilling tool is not affected.

The invention relates to a leaking stoppage tool for a drilling leakage stratum, and relates to the field of petroleum drilling leaking stoppage, the leaking stoppage tool comprises a deformable plugging assembly, a sealing structure is arranged at the end of the deformable plugging assembly, an expansion assembly is arranged in the deformable plugging assembly, and the expansion assembly is in sliding connection with the deformable plugging assembly; and the expansion assembly is used for performing reaming deformation on the deformable plugging assembly in the self-contraction state to be in the expansion state. The anti-leakage plugging device has the advantages that effective plugging can be achieved under the condition that the diameter of a well hole is not reduced, the reliability is high, the cost is low, the period is short, and the number of used machines and tools is small, different measures can be taken for different degrees of leakage working conditions, the good anti-leakage plugging effect is achieved, and the normal drilling effect of well drilling is guaranteed.

The invention provides a long open hole malignant leakage well non-pulling-out plugging measuring integrated construction method which comprises the following steps: after leakage occurs, firstly, determining the leakage position of a long open hole well section through a leakage layer identification system, preparing a multi-grading plugging working solution according to the leakage speed, secondly, opening a plugging bypass system, interrupting a drilling system, and finally, according to the constructed long open hole well condition, determining the plugging position of the long open hole well section. And a special leaking stoppage construction process is determined, after leaking stoppage operation is completed, the leaking stoppage bypass system is closed, and the drilling system is recovered. The special leaking stoppage construction technology comprises an annular reverse extrusion technology and a direct extrusion sealing technology, the tripping time can be greatly shortened, and the plugging capacity of leaking stoppage slurry can be guaranteed. According to the method, quick and efficient treatment of well leakage is achieved on the premise that drilling is not carried out, and the existing technical problems that a leakage layer is uncertain, multiple times of invalid leakage stoppage are not achieved, large-particle leakage stoppage slurry is difficult to pump in under the condition of a drilling tool combination, the leakage stoppage time is prolonged due to multiple times of drilling, and the leakage stoppage construction technology cannot meet the leakage layer stoppage requirement to the maximum extent are solved.

This invention provides a water-based drilling fluid for solidifying the wellbore in deep oil and gas wells at depths of 10,000 meters, along with its preparation method and application, belonging to the field of drilling fluid technology. The water-based drilling fluid for solidifying the wellbore in deep oil and gas wells at 10,000 meters comprises the following raw materials in parts by weight: 100 parts water, 1-5 parts modified clay shearing agent, 2-4 parts hydrophobic associating polymer flow modifier, 3-8 parts plugging agent, 2-5 parts hyperbranched polymer filtration reducer, and 1-3 parts cemented plugging wall-solidifying agent. This invention also provides a method for preparing the above-mentioned drilling fluid. In this invention, the flow modifier, plugging agent, filtration reducer, and wall-solidifying agent work synergistically to enable the drilling fluid to maintain good rheological, filtration, plugging, and inhibition properties for a long time under 240°C and saturated salt conditions, achieving a strong wall-solidifying effect. This effectively maintains the stability of the wellbore in deep oil and gas wells at 10,000 meters, preventing well collapse, lost circulation, blowouts, and other drilling complications, and can be used in drilling deep oil and gas wells at 10,000 meters.

The invention relates to the technical field of petroleum drilling auxiliaries, and discloses a preparation method of a plugging agent for petroleum drilling, which comprises the following steps: constructing an elastic-rigid gradient composite system, respectively introducing a selective liquid absorption component into an elastic layer and a rigid layer, and preparing an osmotic gradient regulating component to regulate and control liquid phase permeation. The preparation method comprises the following steps: preparing three types of multi-stage slow-release curing components with different release rates, adding a stage-triggered release-promoting auxiliary agent and a curing synergist, and finally preparing the composite plugging agent by adopting a step-by-step mixing process. Stress adaptability is achieved through an elastic-rigid gradient structure, performance dynamic optimization is achieved through selective liquid absorption and permeation regulation and control, time sequence accurate matching is achieved through multi-section type slow-release curing, and the technical problems that a traditional plugging agent is single in hardness and prone to cracking, static performance cannot be dynamically adjusted, and curing time sequences are not matched are solved. And the loading capacity, the sealing performance and the long-term stability of the leaking stoppage layer are obviously improved.

This invention relates to the field of drilling fluid auxiliary circulation systems, specifically a rotary circulation anti-sticking device comprising a central pipe with an axial flow channel and a rotary casing. The invention features a reasonable and compact structure and is easy to use. In the event of a circulation system failure, it is first connected to the drilling platform pressure manifold via a pipe joint and a high-pressure water hose, and then connected to the wellhead drill string via the rotary casing, allowing the drilling fluid to quickly recirculate. Simultaneous rotation of the drill string at this time effectively prevents sand accumulation and stuck pipe or sticking. When stuck pipe or lost circulation occurs in a horizontal well section, the cable is first passed through this device and then connected to a string of tools such as detection tools, explosive release tools, or retrieval tools before being lowered into the well. It is then connected to the drilling platform pressure manifold via a union joint and a high-pressure water hose, allowing the high-pressure drilling fluid to propel the tool string forward to a predetermined position, completing the detection, deployment, and retrieval procedures.

The invention relates to the technical field of oil exploitation, in particular to an indoor evaluation method and device for leakage-stopping drilling fluid passing through a rotary guiding system, and the method comprises the steps that when the leakage-stopping drilling fluid passes through screens at the left end and the right end of a mounting cylinder, the leakage-stopping drilling fluid generates different pressures on the left end and the right end of the screens; respectively acquiring pressure data of corresponding positions through a first acquisition probe and a second acquisition probe of the pressure sensor; calculating the pressure amplification of the collected pressure data by using the following formula; and evaluating the capability of the over-rotation steering drilling tool screen through the pressure amplification. The device is used for simulating the process that the drilling fluid circularly passes through the screen of the rotary steering drilling tool, the function of preferentially screening the drilling-following plugging drilling fluid for the rotary steering drilling tool indoors is achieved, the experiment cost and risk are remarkably reduced, and the problems that the experiment cost of the capability of the drilling-following plugging drilling fluid passing through the rotary steering drilling tool on site is high, and the risk is large are solved. And the blank of the indoor screening and evaluation technology of the plugging-while-drilling drilling fluid for the rotary steering drilling tool is filled.

A lost circulation detection device includes a first detection member and a second detection member, a first signal transmitter and a first signal receiver are disposed on the first detection member, and the first signal transmitter transmits a signal along an axial direction of a rockshaft so that the first signal receiver acquires data information of drilling fluid in the axial direction of the rockshaft; a fluid channel penetrating through the second detection member is disposed in the second detection member, and the fluid channel is configurable to be in communication with the rockshaft; a second signal transmitter and a second signal receiver are disposed oppositely on two sides of the fluid channel, and the second signal transmitter transmits a signal along a center line of a second accommodating groove, so that the second signal receiver acquires data information of drilling fluid in a circumferential direction of the rockshaft.

The application discloses a kind of overflow leakage monitoring methods, systems and devices of throttling drilling.The method includes the instantaneous outlet flow of mud in the process of throttling drilling is acquired in real time, according to preset time sliding window, the moving average sequence of instantaneous outlet flow of current time is determined, and the moving standard deviation of instantaneous outlet flow of current time is determined based on moving average sequence;According to moving standard deviation, overflow leakage dynamic early warning interval is set;According to preset time sliding window, the difference of moving average of current time instantaneous outlet flow and the moving average of next time instantaneous outlet flow is determined;Difference is judged whether it accords with overflow leakage dynamic early warning interval.Can eliminate the influence of abnormal fluctuation of instantaneous outlet flow on overflow leakage early warning result, dynamically adjust the early warning interval of overflow leakage, and more timely and accurately carry out overflow leakage early warning in the process of throttling drilling.

The invention discloses an annulus liquid level monitoring system and method. The system comprises a nitrogen generation pressure control module, a sound wave control module, a liquid level monitoring module and an actuator control module, the nitrogen generation pressure control module is connected with a drilling gas source, the sound wave control module is arranged on an annular liquid level wellhead rotary blowout preventer four-way joint, and the liquid level monitoring module and the actuator control module are arranged on a pressure control drilling operation table. According to the technical scheme of the embodiment, the annulus liquid level monitoring system is constructed by integrating the nitrogen generation pressure control module, the sound wave control module, the liquid level monitoring module and the actuator control module, and the system is integrated on the pressure control drilling equipment, so that continuous monitoring of the drilling annulus liquid level under the working condition of well leakage and return in the pressure control drilling process is achieved, and the drilling efficiency is improved. Meanwhile, according to the annulus liquid level height and the real-time annulus liquid level bottom hole pressure, actuator control parameters and grouting parameters are guided in real time, so that the problem that the annulus liquid level drops due to return loss in the drilling process is quickly responded, and the well control safety is improved.

The invention discloses a pressure control well drilling method. The method comprises the following steps that temperature-pressure coupling characteristics of temperature and pressure are calculated according to a temperature parameter, a pressure parameter, bottom hole pressure and bottom hole temperature; according to the drilling temperature parameters, the drilling pressure parameters and the temperature-pressure coupling characteristics, the drilling bottom hole pressure initial value is calculated; and the opening degree of the throttling valve is adjusted, so that the difference value between the drilling well bottom pressure and the well bottom target pressure is smaller than a first preset threshold value. According to the pressure control well drilling method, temperature and pressure prediction tasks can be coupled, the prediction precision is improved through the relevance between the tasks, after the well bottom pressure prediction value is obtained, stable return pressure is provided for a well mouth by adjusting the throttling valve, meanwhile, pressure distribution in a well shaft is dynamically calculated according to the real-time well mouth return pressure, and the well drilling precision is improved. And whether the formation pressure is balanced or not is judged, circulation is conducted in sequence till adjustment is finished, well kick and well leakage accidents are prevented, and effective supplement and improvement are achieved for a traditional drilling technology.

A method for introducing cavitation downhole includes: generating cavitation nuclei, introducing the cavitation nuclei into drilling fluid, delivering the drilling fluid downhole, and activating a downhole acoustic source. A method for preventing lost circulation includes: introducing cavitation nuclei downhole, introducing a plugging material downhole, wherein the plugging material comprises microcapsules of resin and a crosslinking agent, activating an acoustic source capable of inducing cavitation; and rupturing the microcapsules of the crosslinking agent to prevent lost circulation.

The application provides a lost formation fracture width determination method, device and storage medium. The method comprises the following steps: S10, establishing a fracture width inversion calculation model based on drilling fluid solid phase particle size and concentration; S20, determining the volume concentration of the drilling fluid solid phase particle; S30, determining the characteristic particle size value of the drilling fluid solid phase particle; S40, calculating the maximum lost fracture width; and S50, determining the formation lost fracture width range. The application provides a fracture width inversion calculation model based on drilling fluid solid phase particle size and concentration, overcomes the neglect of the drilling fluid solid phase particle in the traditional method, can timely and accurately determine the formation lost fracture width, and provides a reliable basis for the particle size selection of the plugging material and the plugging slurry formula design.

The utility model discloses a portable novel drilling fluid outlet flow measuring device. The portable novel drilling fluid outlet flow measuring device comprises a sealing shell, a gear set, an inductance type rotation angle sensor, an automatic rebounding device and a flow blocking device, wherein the gear set, the inductance type rotation angle sensor and the automatic rebounding device are installed in the sealing shell. The inductance type rotation angle sensor is driven by the gear set; during use, the driving end of the flow blocking device extends into the slurry outlet pipeline, the driven end of the flow blocking device extends out of the slurry outlet pipeline, enters the sealing shell and is in driving connection with the gear set, and when drilling fluid flows to a slurry groove through the pipeline, the driving end of the flow blocking device is driven to move, so that the slurry flow can be measured; and the automatic rebounding device is matched with the gear set to drive the gear set to automatically rebound to a zero position state. The mud flow measuring device is simple in structure, low in machining cost, convenient to operate, suitable for measuring the mud flow at an outlet in a petroleum and natural gas extraction drilling site, and capable of conducting early warning and monitoring on dangerous working conditions such as well kick and well leakage possibly occurring in the drilling process.

The application provides a drilling leak stoppage valve. The drilling leak stoppage valve comprises a leak stoppage valve body, an elastic member, a sliding sleeve, a ball seat and a ball catcher. The leak stoppage valve body comprises a first cavity, an inner step and a first opening on the side wall of the body. The bottom end of the elastic member abuts against the inner step. The sliding sleeve is slidably arranged in the first cavity and the bottom end is supported by the elastic member. The sliding sleeve comprises a second cavity and a second opening on the side wall thereof, and the second opening can be moved to a position in alignment with the first opening when the elastic member is compressed. The ball seat is arranged in the second cavity and is positioned between the second opening and the bottom end of the sliding sleeve, the ball seat is connected to the inner wall of the sliding sleeve and has a ball seat opening for accommodating a ball, and the ball seat can be deformed at a predetermined pressure to increase the radial size of the ball seat opening. The ball catcher is connected to the bottom end of the leak stoppage valve body. The drilling leak stoppage valve is more stable in performance and is not affected by the high temperature and high pressure at the bottom of the well, and is convenient for plugging the well leakage under the high temperature and high pressure environment.

Because it is a continuous monitoring process with strict quality control from the raw materials, this process allows the selection of the desired particle size for the requested product. The alkalization of the raw materials for modification ensures a solubility greater than 97% and results in a high-quality product mix in acidic solutions. It provides a wide range of particles for the prevention and control of lost circulation, reinforces the mud through bridging, generating low permeability, and is compatible with water-based and oil-based drilling systems. This provides optimal conditions in drilling operations to reduce or eliminate partial and / or total circulation losses.It has a range of products with granulometries: fine, medium, coarse and extra coarse for the production zone of the oil industry, these presentations comply with the parameters required by PEMEX, "single operational guide to determine the technical specifications of ultra-low invasion plugs for well interventions, First Version, July 2021."

A method of introducing cavitation downhole includes creating cavitation nuclei, introducing cavitation nuclei to a drilling fluid, delivering the drilling fluid downhole, and activating an acoustic source downhole. A method of preventing lost circulation includes introducing cavitation nuclei downhole, introducing lost circulation materials downhole where the lost circulation materials include a resin and microcapsules of a crosslinking agent, activating an acoustic source which may induce cavitation; and rupturing the microcapsule of the crosslinking agent to prevent lost circulation.

The invention provides a leakage horizon prediction method based on GBDT and multi-source feature fusion, and the method comprises the steps: collecting leakage state data during a leakage accident to construct a multi-source feature data set, and carrying out the preprocessing of the multi-source feature data set; performing feature fusion on the preprocessed multi-source feature data set to form a fused feature data set; performing feature extraction on the fused feature data set by using a feature selection algorithm to generate a feature sequence; training the feature sequence by adopting a GBDT algorithm to form a leakage horizon prediction model; and predicting the leakage position in the drilling operation process by using the trained leakage position prediction model. According to the leakage horizon pre-method based on GBDT and multi-source feature fusion, errors are reduced by introducing a model optimization mechanism, and the prediction precision of the leakage horizon in the drilling operation process is improved.

The invention discloses a while-drilling leaking stoppage tool and a using method. The while-drilling leaking stoppage tool comprises an upper connector and a lower connector which are in threaded connection, a leaking stoppage hole is formed in the outer wall of the upper connector, a sliding sleeve ball seat is installed in the upper connector, a spring is installed in the lower connector, the spring makes contact with the sliding sleeve ball seat, and a pressure relief hole is formed in the outer wall of the lower connector. The plugging agent can be applied to plugging of formation fracture leakage in the drilling process of sidetrack drilling of a vertical well, a directional well, a horizontal well and an old well, drilling fluid is prevented from continuously leaking to formation fractures, the drilling fluid can normally circulate, and normal drilling is achieved; the operation process is simple, the plugging agent can smoothly flow to the annulus of the leakage position from the interior of the drill rod, the plugging effect is good, and the well drilling plugging period is shortened.

The invention relates to the technical field of petroleum drilling, in particular to an inorganic gel composite plugging agent and a plugging method.The inorganic gel composite plugging agent suitable for the malignant leakage stratum.The inorganic gel composite plugging agent suitable for the malignant leakage stratum.The inorganic gel composite plugging agent suitable for the malignant leakage stratumcomprises inorganic gel and a structuring agent, and the structuring agent comprises cottonseed hull powder, walnut shell powder, vermiculite powder and superfine calcium carbonate; the mass ratio of the cottonseed hull powder to the walnut shell powder to the vermiculite powder to the superfine calcium carbonate is (2-4): (3-5): (1-3): (2-4). The plugging slurry prepared from the inorganic gel composite plugging agent suitable for the malignant leakage formation and well slurry can be quickly crosslinked with a thickening agent to form a thickened and solidified substance, has high pressure bearing capacity, can improve the pressure bearing capacity of the formation by 4 MPa or above, can improve the thickening and solidifying time by 4 h or above, meets the site construction time requirement, and has good application prospects. And the plugging construction time can be greatly shortened.

The present application belongs to the technical field of oil drilling, and particularly relates to a cementing plugging and plug leaving method for oil drilling, which comprises the following steps: throwing gravel into the well above 80-100 m of the leakage layer through the water eye of the drill pipe to plug the cracks, filling with plugging slurry, and finally performing cementing operation to leave a cement plug in the well, thereby realizing plugging and plug leaving. The cementing plugging and plug leaving method for oil drilling is suitable for the case that the existing plugging is invalid after well leakage occurs, and the cement plug cannot be left. The method has simple construction process, high operability, and high success rate of plug leaving, and has strong guidance for the cementing plugging and plug leaving in the drilling site, and is very worthy of popularization and application in the large lost circulation filling well sidetracking site.

The invention belongs to the technical field of petroleum and natural gas drilling, and particularly relates to a plugging agent plugging process simulation device and a plugging effect evaluation method. The device comprises a crack simulation part and a rock core clamping part. The crack simulation part comprises a first rock core and a second rock core, and a longitudinally arranged simulation crack is formed between the first rock core and the second rock core. The rock core clamping part comprises a first clamping plate, a second clamping plate, a third clamping plate and a fourth clamping plate which are located on the outer side of the crack simulation part, and a liquid inlet and a liquid outlet are formed in the third clamping plate and the fourth clamping plate respectively. The simulated crack in the device has an uneven inner surface and is closer to the shape of a real crack, so that the plugging agent plugging simulation process performed by using the device is closer to the actual plugging working condition, and a reliable structural foundation is provided for subsequent plugging effect evaluation of different plugging particle proportions.

The application discloses a high-dispersion fiber leak-stopping agent for water-based drilling fluid and application and application method thereof, and relates to the technical field of drilling fluid leak-stopping used in oil and gas exploitation. The high-dispersion fiber leak-stopping agent for water-based drilling fluid contains 10.0-20.0% of high-dispersion high-aspect-ratio synthetic fiber, 10.0-40.0% of high-temperature-resistant natural fiber, 10.0-20.0% of wood fiber, 10.0-30.0% of spina date kernel particles and 5.0-10.0% of microporous foam aluminum particles in percentage of mass. The high-dispersion fiber leak-stopping agent for water-based drilling fluid can be directly added into the water-based drilling fluid, can pass through the internal gap of the rotary steering tool and will not block the rotary steering tool, and the rotary steering drilling tool does not need to be first tripped out. The application solves the problem of leak-stopping while drilling under the condition of the rotary steering drilling tool. The application provides technical support for the exploration and development of unconventional oil and gas resources such as shale gas, coalbed gas and tight gas.

The application discloses a well leakage monitoring method for a drilling process. The method comprises the following steps: acquiring a first pressure and a first temperature at a first annular space measuring point of a target well, a second pressure and a second temperature at a second annular space measuring point of the target well, a drilling fluid inlet flow rate and an inlet density in real time; determining drilling fluid densities at the first annular space measuring point and the second annular space measuring point according to a ground pressure and a ground temperature in real time; determining a first annular space fluid flow rate of the target well under a no-leakage condition based on the first pressure, the first temperature, the second pressure, the second temperature, the inlet flow rate and the inlet density; determining a second annular space fluid flow rate of the target well in real time; determining a leakage monitoring coefficient of the target well based on the first annular space fluid flow rate and the second annular space fluid flow rate; and determining that the target well has well leakage in the case that the leakage monitoring coefficient is less than or equal to a preset leakage monitoring threshold. The application can monitor well leakage and calculate a leakage rate in real time, so as to ensure drilling safety.

A method for characterizing a subterranean interval in which drilling fluid is leaking includes receiving surface drilling values captured while drilling a wellbore through the subterranean interval. The method also includes analyzing the surface drilling value and identifying a contact bottom hole surface drilling value and a contact bottom hole mechanical specific energy (MSE) value. The method also includes identifying a first point of change in the contacted downhole surface drilling value. The method also includes identifying a second point of change in the contacted downhole MSE value. The method further includes determining a cause of a leakage event in the subterranean interval based on the first point of change and the second point of change.