Measuring rod, through-drill-bit measurement-while-drilling device and method

Abstract

The invention discloses a measuring rod and an over-drill-bit measurement-while-drilling device and method. The measuring rod is provided with at least three expansion jackets at intervals in the radial direction, and any two expansion jackets and at least one part of the underground side wall form a measuring cavity after expansion. A liquid injection hole is formed in the part, in the measuring cavity, of the measuring rod, and a liquid injection channel communicated with the liquid injection hole is formed in the measuring rod in the radial direction; the measuring rod is provided with a measuring cabin between two adjacent expansion jackets, and the measuring cabin is at least integrated with a pressure sensor and a neutron detection assembly; the pressure sensor is used for collecting the pressure in the measuring cavity; the neutron detection assembly is used for measuring stratum parameters in the measurement cavity in a pressurized state. The multiple expansion jackets are used for forming the measuring cavities with different lengths so as to eliminate sealing failure caused by irregular borehole diameters, or the multiple expansion jackets are used for forming the multiple spaced measuring cavities so as to reduce the trust risk of a single data source, and a pressure sensor, neutron detection and the like are used for measuring stratum data in a pressurized environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of drilling equipment, and particularly relates to a measuring rod, a through-drill-bit measurement-while-drilling device and a method. BACKGROUND

[0002] Sandstone uranium mine, as an important part of uranium resources, has an irreplaceable strategic position in the nuclear energy industry chain due to its low mining cost, large resource quantity and technical advantages such as in-situ leaching mining.

[0003] In the process of mining sandstone uranium mine, logging technology is the core means to ensure efficient development of resources, optimize mining schemes and reduce environmental risks. However, there are some technical bottlenecks and deficiencies in the actual application of existing logging technology, mainly reflected in the identification accuracy of low-grade uranium mines, the precision measurement of permeability evaluation, and the real-time performance of in-situ leaching mining dynamic detection. Through-drill-bit logging is a commonly used data acquisition method, which transmits a small-diameter logging instrument through a drill string, passes through a special through-hole drill bit into an open hole section, and thus realizes rapid and efficient data acquisition. There are two ways of through-drill-bit logging data acquisition, one is real-time transmission through a cable connected to the logging instrument, and the other is reading out data through a storage port, but this method has relatively high requirements for the battery of the instrument, which needs to provide power during continuous operation.

[0004] However, the existing through-drill-bit probe rod still has some deficiencies in the detection of sandstone uranium mine, for example, the traditional gamma technology is significantly interfered by elements such as thorium and potassium, and has insufficient detection sensitivity for low-grade ore bodies with low uranium content, resulting in resource waste. The indirect inversion model of resistivity, acoustic wave and other parameters to calculate permeability has a high error rate and cannot meet the precise design requirements of in-situ leaching liquid injection parameters. Therefore, it is of great significance for efficient exploitation of uranium resources to design and develop a through-drill-bit measurement-while-drilling device and method to realize accurate detection and coupled analysis of important parameters such as uranium content and permeability. SUMMARY

[0005] Therefore, the present application discloses a measuring rod in the first aspect, at least three expansion jackets are arranged at intervals along the radial direction of the measuring rod, and at least a part of the sidewall of the well is formed into a measuring cavity after expansion of any two expansion jackets; a liquid injection hole is arranged in the part of the measuring rod in the measuring cavity, and a liquid injection channel in communication with the liquid injection hole is arranged along the radial direction of the measuring rod; a measuring cabin is arranged between the adjacent two expansion jackets of the measuring rod, and the measuring cabin is integrated with at least a pressure sensor and a neutron detection assembly; the pressure sensor is used for collecting the pressure in the measuring cavity; and the neutron detection assembly is used for measuring the formation parameters in the measuring cavity under the pressurized state.

[0006] In this invention, the measuring rod is provided with an inflation hole inside the expansion jacket, and the measuring rod is provided with an inflation channel communicating with the inflation hole in the radial direction.

[0007] In this invention, the inflation holes of the multiple expansion jackets are connected to the same inflation channel.

[0008] In this invention, a one-way valve is provided at the inflation port.

[0009] In this invention, the air holes of the multiple expansion jackets are connected to different inflation channels.

[0010] In this invention, the expansion jacket includes a mesh skeleton and a sheath covering the mesh skeleton; the mesh skeleton is made of titanium alloy; and the sheath is formed by rubber injection molding.

[0011] In this invention, the measuring rod includes an upper rod, a lower rod, and at least three expansion joints located between the upper rod and the lower rod, with a measuring joint disposed between any two expansion joints; the upper rod, lower rod, expansion joints, and measuring joints are respectively provided with portions of the injection channel in the radial direction; the expansion joint is provided with the expansion jacket, and the expansion joint is provided with the inflation hole within the coverage area of ​​the expansion jacket; the expansion joint is provided with an inflation pipe communicating with the inflation hole in the radial direction; the inflation channel is connected to an external gas device after passing through the injection channel.

[0012] In this invention, the measuring rod includes at least one connecting section; the connecting section is disposed between any adjacent expansion joint and the measuring section; a portion of the injection channel is provided in the connecting section radially.

[0013] Furthermore, a second aspect of the present invention discloses a bit-through-drilling measurement device, the measurement device comprising a drill bit, a drill rod, and a measuring rod; the drill rod is connected to the drill bit; the measuring rod is deployed inside the drill rod, and the measuring rod can extend through a radial through-hole of the drill bit along the drilling direction.

[0014] Furthermore, a third aspect of this invention discloses a method for through-bit measurement while drilling, utilizing the aforementioned through-bit measurement while drilling device. The method includes: driving the drill string assembly (drill rod and drill bit) to the target formation via external drilling equipment; then lifting the drill string assembly via the drilling equipment; lowering the measuring rod along the internal cavity of the drill rod; after the measuring rod passes through the radial through-hole of the drill bit, causing two adjacent expansion jackets to expand circumferentially and form a measurement cavity with the downhole sidewall; injecting filling fluid into at least two of the measurement cavities through the injection channel to create a pressurized environment within the measurement cavities; and performing measurement operations under the pressurized environment using pressure sensors and neutron detection components in each measurement chamber.

[0015] Compared with existing technologies, this invention can utilize multiple expansion jackets to form measurement cavities of different lengths, eliminating sealing failures caused by irregular well diameters; it can also utilize multiple expansion jackets to simultaneously form two spaced measurement cavities, reducing the trust risk of a single data source; and it can utilize pressure sensors and neutron detection to measure formation data.

[0016] Other advantages, objectives and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination or study, or may be learned from the practice of the invention. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0018] Figure 1 This is a schematic diagram of one structure of the measuring rod of the present invention;

[0019] Figure 2 for Figure 1 A magnified view of a portion of the image;

[0020] Figure 3 This is a schematic diagram of another structure of the measuring rod of the present invention.

[0021] Figure labels: 110, upper rod; 121, first expansion joint; 122, second expansion joint; 123, third expansion joint; 131, first measuring section; 132, second measuring section; 140, connecting section; 150, lower rod; 31, cylinder; 32, expansion jacket; 41, air inlet pipe; 42, air inlet; 50, liquid inlet hole; 60, liquid inlet channel. Detailed Implementation

[0022] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. It should be noted that in this application, "radial" specifically refers to the direction along the longitudinal axis of the drill pipe, "radial" is the horizontal direction perpendicular to the axis, and "drilling direction" is the positive direction in which the drill bit advances into the depth of the formation.

[0023] This invention discloses a measuring rod that can be applied in logging-while-drilling (LWD) scenarios. The measuring rod overcomes the technical bottleneck of traditional LWD tools being limited to measurements inside the drill pipe, enabling multi-segment sealed measurements in the open-hole section below the drill bit, thereby obtaining more accurate formation parameters within the target area.

[0024] like Figure 1 and Figure 2 As shown, the measuring rod is arranged radially as follows: an upper rod 110, a first expansion joint 121, a first measuring joint 131, a second expansion joint 122, a second measuring joint 132, a third expansion joint 123, and a lower rod 150. The upper rod 110 has a standard threaded interface at its top for connecting to external equipment. The upper rod 110, first expansion joint 121, first measuring joint 131, second expansion joint 122, second measuring joint 132, third expansion joint 123, and lower rod 150 are each constructed with a through radial inner hole. All the radial inner holes combine to form a liquid injection channel 60. An external liquid device injects or extracts liquid into or from the liquid injection channel 60 through the opening of the radial inner hole at the upper end of the upper rod 110. Simultaneously, each measuring joint is constructed with a liquid injection hole 50. The liquid injection hole 50 connects the liquid injection channel 60 to the outside of the measuring rod. After two adjacent expansion joints expand and form a sealed measuring chamber with the downhole sidewall, the external fluid equipment continuously injects fluid into the measuring chamber through the injection channel 60 and injection port 50, creating a pressurized environment within the measuring chamber. A pressurized environment refers to the principle, using Pascal's Law, that pressure applied to any part of a closed fluid will be transmitted in all directions without change. The pressure continuously applied by the external fluid equipment within the measuring chamber is converted into pressure within the measuring chamber.

[0025] Furthermore, the first expansion joint 121, the second expansion joint 122, and the third expansion joint 123 are all constructed with a titanium alloy cylinder 31 and an expansion jacket 32 ​​surrounding the cylinder 31. The expansion jacket 32 ​​is composed of a mesh skeleton woven from titanium alloy wire and a neoprene rubber injection molded sheath. A sealed space is formed between the cylinder 31 and the expansion jacket 32. The cylinder 31 has an air inlet 42 that connects to the injection channel 60. The air inlet 42 connects to the air inlet pipe 41. The end of the air inlet pipe 41 that connects to the air inlet 42 is located inside the injection channel 60, and the other end extends upward through the injection channel 60 and connects to an external gas device. The external gas device inflates the space between the cylinder 31 and the expansion jacket 32 ​​through the air inlet pipe 41 and the air inlet 42. After being inflated, the expansion jacket 32 ​​expands circumferentially away from the cylinder 31 until it is in close contact with the downhole sidewall. The external gas device can sense the pressure change inside the gas filling pipe 41. When the pressure increase rate inside the gas filling pipe 41 is sensed to decrease significantly, it indicates that the expansion jacket 32 ​​is in contact with the downhole sidewall. When the pressure increase rate inside the gas filling pipe 41 is sensed to be too slow or to stop, it indicates that the expansion jacket 32 ​​is in close contact with the downhole sidewall and forms a seal.

[0026] Furthermore, a one-way silicone valve is provided at the inflation port 42. The silicone valve is used to prevent the air between the expansion jacket 32 ​​and the cylinder 31 from flowing back into the inflation pipe 41 within a certain pressure difference, so that the expansion jacket 32 ​​can be self-holding after inflation. At the same time, when an external gas device provides sufficient negative pressure into the inflation pipe 41, it can exceed the pressure difference of the silicone valve, so that the gas in the expansion jacket 32 ​​can be extracted.

[0027] Furthermore, in this invention, the expansion sleeve 32 is a cylindrical body open at both ends. The measuring section has a central inner groove and a central outer groove with an inner and outer stepped longitudinal cross-section at the end facing the expansion joint. The end of the cylinder 31 facing the connecting joint 140 is threaded to the central inner groove, and the outer periphery of the end is pressed against the inner wall of the central outer groove to achieve a sealed fixation of the expansion sleeve 32. Preferably, a sealing gasket is provided between the end of the cylinder 31 facing the connecting joint 140 and the central inner groove to enhance the seal at the connection between the connecting joint 140 and the first expansion joint 121.

[0028] In this invention, the inflation holes 42 of the plurality of expansion jackets 32 are respectively connected to different inflation pipes 41. Each inflation pipe 41 is connected to an external gas device.

[0029] In some embodiments, the inflation holes 42 of the plurality of expansion jackets 32 are connected to the same inflation tube 41.

[0030] like Figure 3 As shown, a connecting section 140 is provided between the measuring section and the adjacent expansion section. One end of the connecting section 140 is sealed to the measuring section by means of a thread, and the other end is formed with a central inner groove and a central outer groove with an inner and outer stepped longitudinal cross section, which are used to connect with the cylinder 31 by thread and compress the fixed expansion jacket 32.

[0031] Furthermore, each measuring section in this invention integrates a measuring chamber (not shown in the figure). The measuring chamber integrates a pressure sensor and a neutron detection component. Under this pressurized environment, the measuring chamber can measure formation parameters such as formation permeability using the integrated pressure sensor and neutron detection component.

[0032] The pressure sensor is configured with a range of 0-60 MPa and an accuracy of ±0.1% FS. After the expansion joint 210 is sealed, the pressure sensor records the pressure decay curve and flow rate data of the pressurized environment when external liquid equipment injects liquid into the measuring chamber through the injection channel 60 and injection port to create a pressurized environment. Based on Darcy's law, using the recorded pressure decay curve and flow rate data, combined with parameters such as fluid viscosity (μ) and measuring chamber length (L), the formation permeability (K) can be calculated using the formula. Where Q is the flow rate, μ is the fluid viscosity, L is the length of the measuring chamber, A is the well wall contact area, and m is the slope of the logarithmic pressure curve.

[0033] The neutron detection assembly includes a neutron generator, a neutron detector, and a gamma detector. The neutron generator emits a neutron beam. The neutron detector and neutron generator are radially spaced apart (preferably approximately 150 mm). A neutron signal filter (such as a cadmium / boron screen) can be installed at the front end of the neutron detector to selectively absorb fast neutrons and hyperthermal neutrons, primarily detecting thermal neutrons. A neutron signal amplifier can also be integrated to amplify the thermal neutron count signal to a identifiable threshold. The gamma detector is used to detect gamma rays and preferably integrates a multi-channel pulse amplitude analyzer capable of identifying and stripping characteristic gamma spectral peaks of elements such as uranium, thorium, and potassium.

[0034] In addition, the measurement chamber integrates processing circuitry. This processing circuitry controls the operation of the sensors (such as controlling the emission of the neutron generator and setting the detector sampling interval to ≤10cm), and collects and stores raw data from the pressure sensor, neutron detector, and gamma detector (such as thermal neutron count rate, gamma spectrum, pressure, temperature, etc.).

[0035] Preferably, the processing circuit can also perform real-time or subsequent processing on the acquired raw data. For example, it can calculate neutron porosity (φ_N) using the thermal neutron count rate; and use gamma-ray spectral data, combined with neutron porosity (φ_N), to invert the uranium content (U) and C in the formation using a neutron-gamma multivariate regression model. U =a·R γ +b·φ N +c retrieves the uranium content, where GR is the gamma count rate, and a, b, c are regression coefficients obtained through experimental calibration; stores the calculated formation parameters (such as permeability K, porosity φ, uranium content U, etc.).

[0036] Furthermore, the stored raw data can be retrieved from the measuring rod after drilling is completed and read by an external computer via an interface. The internal sensors of the measuring cabin can be arranged in a radially layered layout to optimize space utilization and signal acquisition.

[0037] Preferably, the measurement chamber is encapsulated within a cylindrical shell that is resistant to high pressure (≥70MPa) and high temperature (≥150℃), and the various sensors and their arrays are integrated inside. The sensors in the measurement chamber can be arranged in a radially layered layout.

[0038] Based on this, the present invention can, on the one hand, utilize three expansion jackets to form measurement cavities of different lengths, eliminating sealing failures caused by irregular well diameters; on the other hand, it can also utilize three expansion jackets to simultaneously form two spaced measurement cavities, each equipped with a measurement chamber for collecting the same formation parameters in adjacent formations, thereby reducing the risk of data loss from a single data source. Furthermore, the present invention utilizes the physical correlation between neutron moderation and gamma spectroscopy to establish a uranium content inversion model, significantly reducing thorium / potassium interference. Finally, it uses an in-situ pressurized environment to simulate in-situ leaching fluid injection conditions and measure formation permeability and other data.

[0039] Furthermore, this invention discloses a drilling-while-drilling measurement device.

[0040] The measuring device includes a drill bit, drill pipe, and measuring rod. The drill bit is connected to the front end of the drill pipe using an API standard NC50 thread. The drill bit has an internal radial through-hole for the measuring rod to pass through, and the inner wall of the radial through-hole is coated with a 0.3mm thick tungsten carbide wear-resistant layer. The drill pipe is made of S135 grade steel tubing, and its internal structure is a hollow channel with an inner diameter larger than the outer diameter of the measuring rod, forming an annular gap relative to the measuring rod. The measuring rod can be coaxially deployed within the hollow channel of the drill pipe and can be lowered by suspension, using gravity to pass through the radial through-hole of the drill bit along the drilling direction into the open hole section; alternatively, the measuring rod can be moved downwards and through the radial through-hole of the drill bit by pumping drilling fluid within the drill pipe.

[0041] The drill bit can employ a multi-stage reaming structure. The front section of the drill bit is inlaid with carbide teeth to break hard rock, while the rear section features a guide ramp to reduce the resistance of the measuring rod during penetration. The surface of the measuring rod can be chrome-plated to reduce the coefficient of friction with the inner wall of the drill pipe. A polyetheretherketone (PEEK) bushing is added to the inner wall of the drill pipe, which is temperature resistant up to 250°C and resistant to drilling fluid corrosion, extending its service life.

[0042] Furthermore, the measuring device in this invention also includes a plug rod. The plug rod is installed inside the drill pipe and drills synchronously with the drill string assembly of the drill pipe and drill bit during drilling. The plug rod can maintain the closure of the radial through-hole of the drill bit during drilling.

[0043] Furthermore, the measuring device in this invention also includes a core rod. The combination of the core rod, drill pipe, and drill bit enables the function of a core drilling rig. During drilling, the core rod is installed inside the drill pipe and cooperates with the drill bit and its radial through-hole to complete the core sampling operation during drilling. It is worth mentioning that the components of the measuring device in this invention, such as the insert rod, inner core rod, drill pipe, and drill bit, and their installation relationships, can directly use existing technologies, such as the outer and inner tube assembly of the S75 wireline coring drill. The dimensions of the existing components only need to ensure that the measuring rod can pass unobstructed through the interior of the drill pipe and the radial through-hole of the drill bit into the open hole below.

[0044] In this regard, the present invention discloses a method for measurement while drilling through the drill bit, comprising the following steps.

[0045] 10. The drill string assembly, consisting of a drill rod and a drill bit (not shown in the figure), is driven by an external drilling device to drill into the target formation, and then the drill string assembly is lifted out by the drilling device.

[0046] The drilling assembly is powered by a top drive unit providing rotational torque. During drilling, a measurement-while-drilling (MWD) system monitors wellbore inclination and azimuth in real time. A three-dimensional geological steering model is constructed using seismic data, and the trajectory is dynamically corrected via adjustable downhole bends to ensure extension within the effective reservoir thickness, avoiding target area deviations caused by fault obstruction or abrupt lithological changes. The drill string assembly is equipped with non-magnetic drill collars and shock absorbers to eliminate geomagnetic interference and reduce lateral vibration. At this stage, the measuring inner rod has not yet entered the drill pipe; the drill pipe cavity serves as the main channel for drilling fluid, with flushing fluid ejected from the drill bit's waterholes, carrying cuttings back to the surface. After the drill string assembly reaches the target formation, it is lowered to form the open-hole section by lifting it. The measuring rod is specifically used for real-time measurement operations in the open-hole section. Furthermore, during drilling, the radial through-holes of the drill bit can remain open or be closed using insert rods. When kept open, the external equipment continuously injects drilling fluid into the drill pipe, which continuously flushes the soil and rock that enters the drill bit from the radial through hole to the outside of the drill bit, and then removes it from the well through the gap between the drill pipe and the well wall.

[0047] 20. Lower the measuring rod along the internal cavity of the drill pipe.

[0048] The measuring rod is lowered into the drill rod via a suspension and deployment mechanism on the ground surface.

[0049] 30. The measuring rod is lowered along the internal cavity of the drill pipe. After the measuring rod passes through the radial through hole of the drill bit, the expansion joints expand circumferentially and form a tight contact seal with the well wall. A measuring cavity will be formed between two adjacent expansion joints.

[0050] 40. Liquid is continuously injected into each measuring chamber through the injection port to create a pressurized environment.

[0051] The pressure sensors and neutron detection components in each of the 50 measurement chambers perform measurement operations within their respective chambers under pressure.

[0052] The pressure sensor measures formation permeability under pressurized liquid conditions. The neutron source operates in pulsed mode, emitting approximately 1 × 10⁻⁶ volts per pulse. 5 Neutrons, as they penetrate the geological strata, undergo elastic scattering with hydrogen atoms in the rocks, slowing them down into thermal neutrons. The neutron detector uses a helium-3 counter tube, which is sensitive to thermal neutrons, recording the thermal neutron count per second. The thermal neutron count rate is positively correlated with the formation porosity, and this is converted into neutron porosity φ through a calibration curve. NThe neutron signal filter 8 removes non-thermal neutron signals with energies higher than 0.025eV, and the neutron signal amplifier 10 amplifies the counting pulse amplitude to a standard 5V level and stores it as measurement data.

[0053] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

[0054] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A measuring rod, characterized in that, The measuring rod is provided with at least three expansion sleeves at radial intervals, and any two of the expansion sleeves form a measuring cavity with at least a portion of the downhole sidewall after expansion; The measuring rod has an injection hole in the portion inside the measuring cavity, and the measuring rod has an injection channel communicating with the injection hole in the radial direction; The measuring rod has a measuring chamber between two adjacent expansion jackets, and the measuring chamber integrates at least a pressure sensor and a neutron detection component. The pressure sensor is used to collect the pressure inside the measuring chamber; The neutron detection assembly is used to measure formation parameters within the measurement chamber under pressure.

2. The measuring rod according to claim 1, characterized in that, The measuring rod has an inflation hole inside the expansion jacket, and the measuring rod has an inflation channel in the radial direction that communicates with the inflation hole.

3. The measuring rod according to claim 2, characterized in that, The inflation holes of the multiple expansion jackets are connected to the same inflation channel.

4. The measuring rod according to claim 3, characterized in that, A one-way valve is provided at the inflation port.

5. The measuring rod according to claim 2, characterized in that, The air holes of the multiple expansion jackets are connected to different inflation channels.

6. The measuring rod according to claim 1, characterized in that, The expansion jacket includes a mesh skeleton and a sheath covering the mesh skeleton; The mesh frame is made of titanium alloy. The sheath is formed by rubber injection molding.

7. The measuring rod according to claim 2, characterized in that, The measuring rod includes an upper rod and a lower rod arranged radially, and at least three expansion joints located between the upper rod and the lower rod, with a measuring joint provided between any two expansion joints; The upper rod, lower rod, expansion joint, and measuring joint are respectively provided with the various parts of the injection channel along the radial direction; The expansion joint is provided with the expansion jacket, the expansion joint is provided with the inflation hole within the coverage area of ​​the expansion jacket, and the expansion joint is provided with an inflation pipe communicating with the inflation hole in the radial direction. The inflation channel is connected to an external gas device after passing through the liquid injection channel.

8. The measuring rod according to claim 7, characterized in that, The measuring rod includes at least one connecting section; The connecting section is disposed between any adjacent expansion section and the measuring section; The connecting joint has a portion of the injection channel arranged radially.

9. A drilling-while-drilling measurement device, characterized in that, The measuring device includes a drill bit, a drill rod, and a measuring rod as described in any one of claims 1 to 9; The drill pipe is connected to the drill bit; the measuring rod is deployed inside the drill pipe and can extend through the radial through hole of the drill bit along the drilling direction.

10. A method for measurement while drilling, characterized in that, Using the through-bit measurement-while-drilling device as described in any one of claims 1 to 9, The through-bit measurement while drilling method includes, The drill string assembly, consisting of the drill rod and the drill bit, is driven by external drilling equipment to drill into the target formation, and then the drill string assembly is lifted out by the drilling equipment. The measuring rod is lowered along the internal cavity of the drill pipe. After the measuring rod passes through the radial through hole of the drill bit, the two adjacent expansion jackets expand circumferentially and form a measuring cavity with the downhole sidewall. The liquid generating device injects filling liquid into at least two of the measuring chambers through the liquid injection channel and creates a pressurized environment in the measuring chambers; The pressure sensors and neutron detection components of each measurement chamber perform measurement operations under the pressurized environment.

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