Downhole leakage measurement while drilling device and method, and leakage plugging system

Abstract

The present invention provides a downhole lost circulation measurement while drilling device and method, as well as a lost circulation plugging system. The measurement while drilling device includes a downhole monitoring unit, a surface monitoring unit, and an MWD information communication feedback unit. The downhole monitoring unit is fixedly mounted on the drill pipe near the drill bit and is capable of measuring temperature, pressure, and annular flow data at the location in real time and transmitting the measured data to the MWD information communication feedback unit. The MWD information communication feedback unit is mounted on the drill pipe and above the downhole monitoring unit. The MWD information communication feedback unit is capable of receiving data measured by the downhole monitoring unit and transmitting it to the surface monitoring unit. The surface monitoring unit is mounted at the wellhead and is capable of determining whether lost circulation has occurred downhole based on the data measured by the downhole monitoring unit. The present invention has the advantages of being able to determine the specific location of lost circulation, having strong anti-interference capabilities, and being adaptable to high-density drilling fluid systems.

Description

Technical Field

[0001] The present invention relates to the technical field of plugging leakage in oil and natural gas drilling, and in particular to a downhole leakage measurement while drilling device and method, and a leakage plugging system. Background Art

[0002] Lost circulation, the phenomenon of drilling fluid leaking into the formation during drilling, is a long-standing and difficult-to-solve technical problem. Lost circulation wastes significant drilling time and can even lead to well failure, resulting in significant economic losses and safety hazards.

[0003] While current plugging technologies continue to evolve and improve, plugging operations still face high risks and a high probability of failure. This is primarily due to a lack of effective assessment of key factors such as the location of the leaking layer, the distribution of leaking channels, leaking pressure, and the sensitivity of the leaking channels to pressure. This results in an inability to accurately determine process parameters such as plugging drill tool placement, plugging slurry particle size distribution, and application pressure. This is the primary reason for low early plugging success rates, long plugging cycles, and significant losses. Currently, hydrodynamic testing and downhole instrumentation are widely used methods for locating leaking layers. However, the measurement accuracy of the hydrodynamic method is affected by multiple parameters such as wellbore diameter, drill tool, and drilling fluid flow rate, resulting in certain errors and inaccurate results.

[0004] Various methods have been proposed for identifying drilling mud loss zones, including mechanical drilling rate observation, core and sand sampling, dynamic hydraulics, pressure gradient, well temperature, rotor flow, radioactive tracer, flow differential, thermocouple, and electrode methods. Two methods are relatively common. The first uses temperature sensors to monitor temperature changes at different depths downhole. The basic principle is that formation temperature increases linearly with depth from the surface, i.e., T = K × h, where K is the temperature gradient (°C / m) and h is the distance from the formation to the surface (m). Long-term practice has shown that this method cannot accurately detect loss locations due to factors such as the non-real-time nature of temperature transmission and the lack of significant temperature changes when the loss volume is small. The second measurement method is to use flow meters, pressure and temperature sensors to measure the flow, pressure and temperature changes of drilling mud. However, due to the constraints of the measurement environment itself, the flow meter used contains movable parts such as rotors. The sensitive surface of the pressure sensor and the movable parts of the flow meter are easily affected by sand particles in the drilling mud, resulting in unreliable or failed measurements. In addition, the current research on leaky layer monitoring equipment at home and abroad all relies on single parameter measurement, has poor anti-interference ability, and cannot adapt to high-density drilling fluid systems.

[0005] Drilling mud loss and the resulting pollution have also received significant attention. Sahar Bakhshian proposed methods for the recovery, treatment, and management of pollution caused by drilling mud spilled on the ground, achieving good results. J.M. Peden and J.G. Tovar proposed a ground equivalent test method for measuring drilling mud loss. This method primarily uses a high-temperature, high-pressure test method to simulate losses caused by mud cake rupture on the ground. However, this method has obvious shortcomings. As the authors note, the test temperature and pressure used on the ground do not necessarily correspond to the actual temperature and pressure downhole. Mohd. Anuar Taib, addressing the issue of 51 out of 113 wells drilled on the Sarawak coast experiencing losses, representing 50% of the total number of wells drilled, categorized the severity of well losses into four levels. Severe losses are defined as wells where all drilling mud is lost, representing approximately 16% of the total number of wells. The solution to this problem was to lift the drill pipe every 300 meters, separate the well sections, and conduct tests section by section to locate the leakage point. Clearly, this method was time-consuming and labor-intensive, and did not meet the requirements for efficient and accurate leakage detection. Regarding leakage mechanism research, Alexandre Lavrov established a drilling mud loss model for common fractured leakage formations and conducted theoretical calculations and simulations. This research has been instrumental in understanding the mechanism of drilling mud loss, but the research still has certain limitations for the leakage formations involved.

[0006] There are many patent documents on this topic at home and abroad, but the methods and measures are mainly concentrated in the following categories:

[0007] One approach is to determine leakage based on the drilling fluid outlet flow rate and changes in the wellhead fluid level. By measuring parameters such as the drilling mud tank level, storage volume, total storage volume, change, mud density, and temperature, one can determine whether overflow or leakage is occurring downhole. Numerous patents and publications have explored this area. However, these methods are limited in that they can only determine the presence and magnitude of leakage, but cannot pinpoint its specific location, providing no direct support for subsequent plugging efforts. Plugging also requires a large amount of mud, resulting in high economic costs.

[0008] The second approach involves adding a low- or high-conductivity indicator additive to the drilling fluid at a constant volume percentage concentration. Two types of probes, installed while drilling, monitor the additive's retention and loss in the drilling fluid circulation system. Comprehensive analysis and assessment can then be used to trace the location and severity of lost circulation. Loss and intensity are determined by using indicators, relying on changes in indicator concentration. The drawbacks of this approach are: first, the high amount of indicator required, which requires continuous addition throughout the drilling process to maintain concentration, increasing costs. This is because the indicator adheres to the formation during drilling, causing loss. Second, if the leak is at a fracture point, the amount of drilling fluid lost is small, making it impossible to determine the location of the lost circulation. Furthermore, monitoring the outflow rate is inaccurate and indirect, leading to high costs for subsequent plugging efforts.

[0009] The third approach, similar to the second method above, involves adding a fixed volume percentage concentration of a radioactive indicator additive to the drilling fluid. Two types of probes installed while drilling monitor the additive's retention and loss within the drilling fluid circulation system. Comprehensive analysis and assessment can then be used to trace the location and severity of lost circulation. In addition to the aforementioned drawbacks, this method requires strict management and handling of the drilling fluid due to its radioactivity to prevent harm to the environment and human health. This significantly increases the environmental cost of its use, making it uneconomical.

[0010] In summary, existing methods for evaluating leaking zones have numerous limitations and are costly. Most rely on analyzing and assessing the pressure of the leaking zone, its sensitivity to pressure, and the properties of the fluids contained within it, and even resort to trial plugging to gain a deeper understanding of the leaking zone. Both analysis and judgment are inherently human and heavily dependent on individual experience, which directly impacts understanding of the leaking zone's properties. Furthermore, the inability to obtain accurate, real-time data on downhole leaks prevents timely and effective plugging operations. This results in significant blindness and delays in plugging, resulting in delayed and low success rates. Summary of the Invention

[0011] The present invention aims to address at least one of the aforementioned deficiencies in the prior art. For example, one object of the present invention is to provide a downhole leakage measurement while drilling device that can pinpoint the specific location of lost circulation, exhibits strong anti-interference capabilities, and is adaptable to high-density drilling fluid systems. Another object of the present invention is to provide a downhole leakage measurement while drilling method that can pinpoint the specific location of lost circulation, exhibits strong anti-interference capabilities, and is adaptable to high-density drilling fluid systems.

[0012] In order to achieve the above object, one aspect of the present invention provides a downhole loss measurement while drilling device, the measurement while drilling device includes a downhole monitoring unit, a surface monitoring unit and an MWD information communication feedback unit, wherein:

[0013] The downhole monitoring unit is fixedly installed on the drill pipe near the drill bit, and the downhole monitoring unit can measure the temperature, pressure and annular flow data of the location in real time and transmit the measured data to the MWD information communication feedback unit;

[0014] The MWD information communication feedback unit is provided on the drill pipe and is located above the downhole monitoring unit. The MWD information communication feedback unit is capable of receiving data measured by the downhole monitoring unit and transmitting it to the surface monitoring unit.

[0015] The surface monitoring unit is arranged at the wellhead and can judge whether lost circulation occurs in the well according to the data measured by the downhole monitoring unit.

[0016] In an exemplary embodiment of an aspect of the present invention, the downhole monitoring unit may include a measuring nipple, an ultrasonic flow meter, a power supply and a transmitting antenna, wherein:

[0017] The measuring sub is fixed on the outer wall of the drill pipe to provide a mounting base for the ultrasonic flowmeter, power supply and transmitting antenna. The power supply supplies power to the ultrasonic flowmeter and transmitting antenna. The ultrasonic flowmeter can measure the annular flow. The transmitting antenna transmits the annular flow measured by the ultrasonic flowmeter to the MWD information communication feedback unit.

[0018] In an exemplary embodiment of an aspect of the present invention, the downhole monitoring unit may further include a temperature sensor and a pressure sensor, which are capable of measuring the temperature and pressure in the downhole annulus.

[0019] In an exemplary embodiment of one aspect of the present invention, the MWD information communication feedback unit may include a receiving antenna and an MWD, wherein the receiving antenna is capable of receiving data transmitted by the downhole monitoring unit, and the MWD is capable of transmitting the data measured by the downhole monitoring unit to the surface monitoring unit in the form of a pulse signal.

[0020] In an exemplary embodiment of one aspect of the present invention, the surface monitoring unit may include a surface monitor and recording software, wherein the recording software can record data transmitted by the MWD information communication feedback unit, and the surface monitor can determine whether lost circulation occurs underground.

[0021] In an exemplary embodiment of one aspect of the present invention, the mud circulation unit may include a mud circulation pipeline, a mud pool and a mud circulation pump, one end of the mud circulation pipeline is connected to the inside of the drill pipe, and the other end is connected to the annulus, and the mud circulation pump injects the mud in the mud pool into the mud circulation pipeline.

[0022] In an exemplary embodiment of one aspect of the present invention, the measurement while drilling device may further include a lifting unit connected to the drill pipe to control the pulling out, running down and stopping of the drill pipe.

[0023] In an exemplary embodiment of one aspect of the present invention, the well depth applicable to the measurement while drilling device may be less than 5000m, the diameter of the wellbore may be 16.59-26.59cm, and the minimum loss flow that can be detected may be 1.2-10m 3 / h.

[0024] Another aspect of the present invention provides a downhole leakage plugging system, which may include a downhole leakage measurement while drilling device as described above.

[0025] Another aspect of the present invention provides a downhole leakage measurement while drilling method, which can be implemented by the downhole leakage measurement while drilling device as described above, and the downhole leakage measurement while drilling method includes the following steps:

[0026] During the drilling process, the downhole monitoring unit measures the temperature, pressure and annular flow data of the location in real time. The surface monitoring unit stops drilling and pauses for a predetermined time after determining that a side leakage has occurred downhole based on the received temperature, pressure and annular flow data.

[0027] The downhole monitoring unit continues to measure the temperature, pressure, and annular flow rate during the pause period. The operator determines whether the leak is between the downhole monitoring unit and the drill bit or above the downhole monitoring unit based on the direction of the annular flow rate.

[0028] If the annular flow direction is from the wellhead to the bottom of the well, the leakage point is between the downhole monitoring unit and the drill bit. The information measured by the downhole monitoring unit is the information of the leakage layer. The mud circulation pump is turned on, and the MWD information communication feedback unit transmits the leakage information to the surface.

[0029] If the annular flow is from the bottom of the well to the wellhead, the leakage point is above the downhole monitoring unit. The drill pipe is lifted and the drill is started. During the drilling process, the downhole monitoring unit continues to collect downhole temperature, pressure and annular flow until the annular flow direction changes from the wellhead to the bottom of the well. Then, the drilling is stopped and the mud circulation pump is started. The MWD information communication feedback unit transmits the leakage information to the surface.

[0030] In an exemplary embodiment of another aspect of the present invention, the pause time may be 60 to 120 seconds, and the annular flow rate may be 1.2 to 10 m 3 / h.

[0031] In an exemplary embodiment of yet another aspect of the present invention, the downhole temperature may be 0 to 150° C., and the downhole pressure may be 0 to 120 MPa.

[0032] In an exemplary embodiment of yet another aspect of the present invention, the lost circulation measurement while drilling method may further include:

[0033] During the drilling process, the continuous decrease or short-term stability of the downhole pressure can be used to determine that it is during the pause period of column removal. At this time, the direction of the annular space flow measured by the downhole monitoring unit is used to determine whether the leaking layer is found. If the leaking layer is not found, it is necessary to continue drilling until the leaking layer is found.

[0034] In an exemplary embodiment of yet another aspect of the present invention, the leak layer information may include the leak layer position, pressure, temperature and leakage flow.

[0035] Compared with the prior art, the present invention has the following advantages:

[0036] (1) The downhole leakage measurement while drilling device of the present invention mainly includes three parts: a downhole monitoring unit, a ground monitoring unit and an MWD information communication feedback unit. The downhole monitoring unit monitors and records data such as downhole flow changes, and then transmits the collected information to the ground monitoring unit through the MWD information feedback unit. The ground monitoring unit provides technical data support for judging the well leakage point based on the collected downhole information, thereby avoiding the problems that the existing leakage layer evaluation device analyzes and judges the leakage point with human factors and relies more on the richness of personal experience. The level of personal level and the amount of experience directly affect the understanding of the properties of the leakage layer, thereby avoiding the problems that the plugging operation is blind and delayed due to the inability to obtain accurate data of downhole leakage in real time and provide timely and effective information for the plugging operation;

[0037] (2) The present invention can provide a new method for evaluating leakage layers for drilling construction. This method can timely and accurately determine the mud leakage layer and the magnitude of liquid leakage, eliminating the influence of human factors, improving the accuracy and effectiveness of subsequent plugging, and providing reliable technical support for plugging work;

[0038] (3) The leakage detection method of the present invention does not require the use of radioactive liquids or additives, does not cause environmental pollution, and has good application and economic value. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The above and other objects and / or features of the present invention will become more apparent from the following description in conjunction with the accompanying drawings, in which:

[0040] Figure 1A schematic structural diagram of a downhole leakage measurement while drilling device according to an exemplary embodiment of the present invention is shown;

[0041] Figures (2a) and (2b) show Figure 1 A partial enlarged view of the .

[0042] Description of reference numerals:

[0043] 1- Downhole monitoring unit, 2- MWD information communication feedback unit, 3- Surface monitoring unit, 4- Wellbore, 5- Leak point location, 6- Drill pipe, 7- Drill bit, 8- Hoisting unit, 9- Mud circulation unit, 91- Mud circulation pipeline, 92- Mud pool, 93- Mud circulation pump. DETAILED DESCRIPTION

[0044] Hereinafter, the downhole lost circulation measurement while drilling device and method, and the lost circulation plugging system of the present invention will be described in detail with reference to exemplary embodiments.

[0045] In a first exemplary embodiment of the present invention, a downhole leakage measurement while drilling device mainly includes a downhole monitoring unit, a surface monitoring unit and an MWD information communication feedback unit.

[0046] The downhole monitoring unit is fixedly mounted on the drill pipe near the drill bit and is capable of measuring the temperature, pressure, and annular flow rate at its location in real time and transmitting the measured data to the MWD information communication feedback unit. The downhole monitoring unit may include a measuring sub, an ultrasonic flowmeter, a power supply, and a transmitting antenna. The measuring sub is fixed to the outer wall of the drill pipe and provides a mounting base for the ultrasonic flowmeter, power supply, and transmitting antenna. The power supply powers the ultrasonic flowmeter and transmitting antenna. The ultrasonic flowmeter is capable of measuring the annular flow rate, and the transmitting antenna transmits the annular flow rate measured by the ultrasonic flowmeter to the MWD information communication feedback unit. Furthermore, the downhole monitoring unit may include a temperature sensor and a pressure sensor capable of measuring the temperature and pressure in the downhole annulus. The flowmeter may also be an electromagnetic flowmeter, but the use of an electromagnetic flowmeter is only suitable for water-based muds and not for oil-based muds.

[0047] The MWD information communication feedback unit is installed on the drill pipe and above the downhole monitoring unit. It can receive data measured by the downhole monitoring unit and transmit it to the surface monitoring unit. Here, the MWD information communication feedback unit may include a receiving antenna and an MWD (mud pulse transmission system). The receiving antenna can receive data transmitted by the downhole monitoring unit, and the MWD can transmit the data measured by the downhole monitoring unit to the surface monitoring unit in the form of pulse signals.

[0048] The surface monitoring unit is installed at the wellhead and is capable of determining whether lost circulation is occurring downhole based on data measured by the downhole monitoring unit. The surface monitoring unit may include a surface monitoring instrument and recording software. The recording software is capable of recording data transmitted by the MWD information communication feedback unit. The surface monitoring instrument is capable of determining whether lost circulation is occurring downhole. The surface monitoring instrument determines lost circulation based on the changing trend of the annular flow rate data measured by the downhole monitoring unit (e.g., a sudden change in the flow rate curve).

[0049] In this exemplary embodiment, the measurement while drilling device may also include a mud circulation unit, which may include a mud circulation pipeline, a mud pool and a mud circulation pump. One end of the mud circulation pipeline is connected to the inside of the drill pipe, and the other end is connected to the annulus. The mud circulation pump injects the mud in the mud pool into the mud circulation pipeline.

[0050] In this exemplary embodiment, the measurement while drilling device may further include a lifting unit connected to the drill pipe to control the pulling out, running down, and stopping of the drill pipe.

[0051] In this exemplary embodiment, the well depth applicable to the measurement while drilling device may be less than 5000m, and the diameter of the wellbore may be 16.59-26.59cm, for example, the diameter of the wellbore is 21.59cm. The minimum loss flow that can be detected may be 1.2-10m 3 / h.

[0052] Figure 1 FIG2 is a schematic diagram showing a structure of a downhole leakage measurement while drilling device according to an exemplary embodiment of the present invention; FIG2a and FIG2b show Figure 1 Partially enlarged diagram in FIG. Among them, FIG (2a) is a structural schematic diagram of the leak point between the drill bit and the downhole monitoring unit; FIG (2b) is a structural schematic diagram of the leak point above the downhole monitoring unit.

[0053] In a second exemplary embodiment of the present invention, as Figure 1 As shown in Figures (2a) and (2b), the downhole leakage measurement while drilling device mainly includes a downhole monitoring unit 1, a surface monitoring unit 3 and an MWD information communication feedback unit 2.

[0054] The downhole monitoring unit 1 is fixedly mounted on the drill pipe 6 near the drill bit 7, and is capable of measuring the temperature, pressure, and annular flow data of its location in real time and transmitting the measured data to the MWD information communication feedback unit 2. The downhole monitoring unit 1 may include a measuring sub, an ultrasonic flowmeter, a power supply, and a transmitting antenna. The measuring sub is fixed on the outer wall of the drill pipe to provide a mounting base for the ultrasonic flowmeter, the power supply, and the transmitting antenna. The power supply supplies power to the ultrasonic flowmeter and the transmitting antenna. The ultrasonic flowmeter is capable of measuring the annular flow, and the transmitting antenna transmits the annular flow measured by the ultrasonic flowmeter to the MWD information communication feedback unit. In addition, the downhole monitoring unit may also include a temperature sensor and a pressure sensor, which are capable of measuring the temperature and pressure in the downhole annulus.

[0055] The MWD information communication feedback unit 2 is mounted on the drill pipe 6 and is located above the downhole monitoring unit 1. The MWD information communication feedback unit 2 is capable of receiving data measured by the downhole monitoring unit 1 and transmitting it to the surface monitoring unit 3. The MWD information communication feedback unit 2 may include a receiving antenna and an MWD (mud pulse transmission system). The receiving antenna is capable of receiving data transmitted by the downhole monitoring unit 1, and the MWD is capable of transmitting the data measured by the downhole monitoring unit to the surface monitoring unit 3 in the form of pulse signals.

[0056] The surface monitoring unit 3 is installed at the wellhead and can determine whether lost circulation is occurring downhole based on the data measured by the downhole monitoring unit 1. Here, the surface monitoring unit 3 may include a surface monitoring instrument and recording software. The recording software can record data transmitted by the MWD information communication feedback unit. The surface monitoring instrument can determine whether lost circulation is occurring downhole. For example, the surface monitoring instrument can determine whether lost circulation is occurring downhole based on the changing trend of the annular flow rate data measured by the downhole monitoring unit (e.g., a sudden change in the flow rate curve).

[0057] In this exemplary embodiment, Figure 1 As shown in FIG, the measurement while drilling device may further include a mud circulation unit 9, which may include a mud circulation pipeline 91, a mud pool 92, and a mud circulation pump 93. One end of the mud circulation pipeline 91 is connected to the upper end of the drill pipe 6, thereby injecting mud into the drill pipe 6. The other end of the mud circulation pipeline 91 is connected to the annulus. The mud pool 92 and the mud circulation pump 93 are disposed on the mud circulation pipeline 91. The mud circulation pump 93 injects mud from the mud pool 92 into the mud circulation pipeline for mud circulation.

[0058] In this exemplary embodiment, Figure 1 As shown in , the measurement while drilling device may further include a lifting unit 8, which is connected to the upper end of the drill rod 6 to control the drill rod 6 to perform pulling out, drilling down and stopping drilling.

[0059] In this exemplary embodiment, the well depth applicable to the measurement while drilling device may be less than 5000m, the diameter of the wellbore may be 21.59cm, and the minimum loss flow rate that can be detected may be 1.2 to 10m 3 / h.

[0060] In a third exemplary embodiment of the present invention, a downhole lost circulation plugging system may include the downhole lost circulation measurement while drilling device described in the first or second exemplary embodiment.

[0061] In a fourth exemplary embodiment of the present invention, a downhole leakage measurement while drilling method can be implemented by the downhole leakage measurement while drilling device described in the first or second exemplary embodiment, and the downhole leakage measurement while drilling method includes the following steps:

[0062] During the drilling process, the downhole monitoring unit measures the temperature, pressure and annular flow data of the location in real time. The surface monitoring unit determines that a side leak has occurred downhole based on the received temperature, pressure and annular flow data, and then stops drilling and pauses for a predetermined time. Here, the pause time can be 60 to 120 seconds, and the annular flow can be 1.2 to 10m 3 / h. The downhole monitoring unit continues to measure the temperature, pressure, and annular flow rate at the location during the pause period. The operator determines whether the leak point is between the downhole monitoring unit and the drill bit or above the downhole monitoring unit based on the direction of the annular flow rate. Here, the downhole temperature can be 0-150°C and the downhole pressure can be 0-120MPa. As shown in Figures (2a) and (2b), the leak point 5 is formed on the wall of the wellbore 4.

[0063] If the annular flow direction is from the wellhead to the bottom of the hole (i.e., the annular flow is negative), the leakage point is between the downhole monitoring unit and the drill bit. The information measured by the downhole monitoring unit is the information of the leakage layer. The mud circulation pump is turned on, and the MWD information communication feedback unit transmits the leakage information to the surface. When the well leakage occurs between the downhole monitoring unit and the drill bit, the flow detected by the ultrasonic flowmeter during the pause should be negative. Since there is no pump speed interference when the pump is stopped (the mud circulation pump is also stopped), the annular flow measured by the ultrasonic flowmeter is very accurate. Then the pump is turned on, and the MWD can upload the leakage information near the drill bit to the surface. Here, the leakage layer information may include the leakage layer location, pressure, temperature and leakage flow. As shown in Figure (2a), when the leakage point location 5 is located on the wellbore 4 between the drill bit 7 and the downhole monitoring unit 1, the drilling fluid in the drill pipe and the drilling fluid in the annular space enter the formation through the leakage point location 5 when drilling is stopped. At this time, the annular flow measured by the downhole monitoring unit 1 is from the wellhead to the bottom of the hole.

[0064] If the annular flow is from the bottom of the well to the wellhead (i.e., the annular flow is positive), the leak point is above the downhole monitoring unit. The drill pipe is lifted and the drill is pulled out. During the drilling process, the downhole monitoring unit keeps collecting downhole temperature, pressure, and annular flow until the annular flow direction changes from the wellhead to the bottom of the well (i.e., the annular flow changes from positive to negative). The drilling is stopped, the mud circulation pump is turned on, and the MWD information communication feedback unit transmits the leak information to the surface. Here, during the drilling process, the downhole pressure is continuously reduced or temporarily unchanged to determine whether it is during the pause period of disassembling the column. At this time, the direction of the annular flow measured by the downhole monitoring unit is used to determine whether the leak layer is found. If no leak layer is found, it is necessary to continue drilling until the leak layer is found. As shown in Figure (2b), when the leak point 5 is located on the wellbore 4 wall above the downhole monitoring unit 1, the drilling fluid in the drill pipe 6 flows out from the drill bit 7 when drilling is stopped. In the annular space, the fluid flows from the bottom of the well to the wellhead, passes through the downhole monitoring unit 1, and then enters the formation through the leak point 5.

[0065] In this exemplary embodiment, the downhole temperature may be 0-150° C., and the downhole pressure may be 0-120 MPa.

[0066] In summary, the beneficial effects of the present invention include at least one of the following:

[0067] (1) The downhole leakage measurement while drilling device of the present invention mainly includes three parts: a downhole monitoring unit, a ground monitoring unit and an MWD information communication feedback unit. The downhole monitoring unit monitors and records data such as downhole flow changes, and then transmits the collected information to the ground monitoring unit through the MWD information feedback unit. The ground monitoring unit provides technical data support for judging the well leakage point based on the collected downhole information, thereby avoiding the problems that the existing leakage layer evaluation device analyzes and judges the leakage point with human factors and relies more on the richness of personal experience. The level of personal level and the amount of experience directly affect the understanding of the properties of the leakage layer, thereby avoiding the problems that the plugging operation is blind and delayed due to the inability to obtain accurate data of downhole leakage in real time and provide timely and effective information for the plugging operation;

[0068] (2) The present invention can provide a new method for evaluating leakage layers for drilling construction. This method can timely and accurately determine the mud leakage layer and the magnitude of liquid leakage, eliminating the influence of human factors, improving the accuracy and effectiveness of subsequent plugging, and providing reliable technical support for plugging work;

[0069] (3) The leakage detection method of the present invention does not require the use of radioactive liquids or additives, does not cause environmental pollution, and has good application and economic value.

[0070] Although the present invention has been described above with reference to the exemplary embodiments and the accompanying drawings, it will be apparent to those skilled in the art that various modifications may be made to the above embodiments without departing from the spirit and scope of the claims.

Claims

1. A downhole leakage measurement while drilling method, characterized in that: The downhole leakage measurement while drilling method is implemented by a downhole leakage measurement while drilling device, which includes a downhole monitoring unit, a surface monitoring unit, an MWD information communication feedback unit and a mud circulation unit, wherein: The downhole monitoring unit is fixedly installed on the drill pipe near the drill bit, and the downhole monitoring unit can measure the temperature, pressure and annular flow data of the location in real time and transmit the measured data to the MWD information communication feedback unit; The downhole monitoring unit includes a measuring nipple, an ultrasonic flow meter, a power supply and a transmitting antenna, wherein: The measuring sub is fixed on the outer wall of the drill pipe to provide a mounting base for the ultrasonic flowmeter, power supply and transmitting antenna. The power supply supplies power to the ultrasonic flowmeter and transmitting antenna. The ultrasonic flowmeter can measure the annular flow. The transmitting antenna transmits the annular flow measured by the ultrasonic flowmeter to the MWD information communication feedback unit. The MWD information communication feedback unit is provided on the drill pipe and is located above the downhole monitoring unit. The MWD information communication feedback unit is capable of receiving data measured by the downhole monitoring unit and transmitting it to the surface monitoring unit. The surface monitoring unit is arranged at the wellhead and can judge whether lost circulation occurs in the well according to the data measured by the downhole monitoring unit; The mud circulation unit includes a mud circulation pipeline, a mud pool and a mud circulation pump. One end of the mud circulation pipeline is connected to the inside of the drill pipe, and the other end is connected to the annulus. The mud circulation pump injects mud in the mud pool into the mud circulation pipeline. The downhole monitoring unit further comprises a temperature sensor and a pressure sensor, which are capable of measuring the temperature and pressure in the downhole annulus; The measurement while drilling device is applicable to wells with a depth of less than 5000m, a wellbore diameter of 16.59-26.59cm, and a minimum loss flow rate that can be detected of 1.2-10m³ / h; The downhole leakage measurement while drilling method comprises the following steps: During the drilling process, the downhole monitoring unit measures the temperature, pressure and annular flow data of the location in real time. After the surface monitoring unit determines that a side leakage occurs in the well based on the received temperature, pressure and annular flow data, it stops drilling and pauses for a predetermined time. The pause time is 60 to 120 seconds. The annular flow rate is 1.2 to 10 m³ / h. The downhole monitoring unit continues to measure the temperature, pressure, and annular flow rate during the pause period. The operator determines whether the leak is between the downhole monitoring unit and the drill bit or above the downhole monitoring unit based on the direction of the annular flow rate. The downhole temperature is 0-150°C and the downhole pressure is 0-120MPa. If the annular flow direction is from the wellhead to the bottom of the well, the leakage point is between the downhole monitoring unit and the drill bit. The information measured by the downhole monitoring unit is the information of the leakage layer. The mud circulation pump is turned on, and the MWD information communication feedback unit transmits the leakage information to the surface. If the annular flow rate is from the bottom of the well to the wellhead, the leak point is above the downhole monitoring unit. The drill pipe is lifted and the drill is pulled out. During the drilling process, the downhole monitoring unit continues to collect downhole temperature, pressure, and annular flow rate until the annular flow rate changes from the wellhead to the bottom of the well. Then, the drill is stopped and the mud circulation pump is started. The MWD information communication feedback unit transmits the leakage information to the surface. During the drilling process, the continuous decrease or short-term stability of the downhole pressure can be used to determine that it is during the pause period of column removal. At this time, the direction of the annular space flow measured by the downhole monitoring unit is used to determine whether the leaking layer is found. If the leaking layer is not found, it is necessary to continue drilling until the leaking layer is found.

2. The downhole leakage measurement while drilling method according to claim 1, characterized in that: The leakage layer information includes the leakage layer location, pressure, temperature and leakage flow.

3. The downhole leakage measurement while drilling method according to claim 1, characterized in that: The MWD information communication feedback unit includes a receiving antenna and an MWD. ​​The receiving antenna can receive data transmitted by the downhole monitoring unit, and the MWD can transmit the data measured by the downhole monitoring unit to the surface monitoring unit in the form of a pulse signal.

4. The downhole leakage measurement while drilling method according to claim 1, characterized in that: The surface monitoring unit includes a surface monitoring instrument and recording software. The recording software can record data transmitted by the MWD information communication feedback unit. The surface monitoring instrument can determine whether lost circulation occurs underground.

5. The downhole leakage measurement while drilling method according to claim 1, characterized in that: The measurement while drilling device further comprises a lifting unit connected to the drill pipe to control the drill pipe to be pulled out of the hole, lowered into the hole and stopped drilling.

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