A low-pollution formation fluid sampling device while drilling

Abstract

This invention relates to the field of formation fluid sampling technology in oil and gas drilling, and particularly to a low-pollution formation fluid sampling device for drilling. It comprises an outer casing, a suction power assembly, and a pre-flushing mechanism assembly. The suction power assembly and the pre-flushing mechanism assembly are fixed to the outer casing by snap rings. The suction power assembly, consisting of a battery, motor, reducer, ball screw, piston, and sampling cylinder, can draw and store formation fluid in the sampling cylinder. The pre-flushing mechanism assembly, consisting of a balance piston, sampling cylinder, guide pipe, and three one-way valves, fills the cavity between the balance piston and the sampling cylinder with buffer solution to cushion the impact of high-pressure formation fluid. Before the sampling operation begins, the pre-flushing mechanism assembly can control the opening and closing of the one-way valves to ensure that the cavity between the sampling cylinder and the balance piston is filled with target formation fluid free of interfering components.

Description

Technical Field

[0001] This invention relates to the field of formation fluid sampling technology in oil and gas drilling, and particularly to a low-pollution formation fluid sampling device for extracting and preserving raw formation fluids. Background Technology

[0002] The chemical composition, viscosity, gas envelope, and solid envelope of a formation reservoir have a significant impact on its physical property evaluation. Obtaining representative formation fluid samples and geological parameters such as fluid type and properties is crucial for accurately determining the hydrocarbon content of the reservoir and for developing reasonable medium- and long-term development plans for oil and gas fields. For these reasons, accurate measurement of reservoir fluid properties is extremely important.

[0003] Currently, there are various methods for obtaining wellbore fluid samples. Among them, obtaining formation fluid while drilling (DWD) can accurately reflect the properties of wellbore fluids during actual drilling. This method uses a DWD tool to extract the original formation fluid through negative pressure suction on the wellbore wall. However, because there is a possibility that non-target formation fluids may enter the tool's sampling chamber before the tool is lowered into the wellbore and before the operation begins, the formation fluid obtained from the target formation may be contaminated with other components. This can distort the data measured in the laboratory, resulting in significant errors and negatively impacting productivity evaluation. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a low-pollution sampling device for formation fluids during drilling.

[0005] The device can extract and store formation fluids, and can perform pre-flushing before extraction to ensure that the extracted and stored fluids contain only the target formation fluids and no other interfering components.

[0006] The technical solution is as follows:

[0007] A low-pollution sampling device for formation fluids while drilling includes an outer shell, a sampling cylinder, a suction power assembly, and a pre-flushing mechanism assembly;

[0008] The outer shell is tubular, and the sampling cylinder is fixedly installed in the middle section of the outer shell;

[0009] The suction power assembly includes a drive assembly, a ball screw, and a piston cylinder. The drive assembly is fixed to the rear section of the outer shell. The drive assembly and the ball screw are driven together. The ball screw and the piston cylinder are connected by a helical transmission. The piston cylinder is located in the middle and rear section of the sampling cylinder. The piston cylinder and the sampling cylinder are in a sliding and sealed fit.

[0010] The pre-rinsing mechanism assembly includes a balance piston, a guide tube, a first one-way valve, a second one-way valve, and a third one-way valve. The balance piston is located at the front of the sampling cylinder and slides and seals with the sampling cylinder. There are three guide tubes: one connects the piston cylinder and the balance piston and is equipped with the first one-way valve; the other two connect to the rear end of the sampling cylinder and are equipped with the second one-way valve and the third one-way valve, respectively. The first one-way valve and the second one-way valve are connected from the inside to the outside, and the third one-way valve is connected from the outside to the inside.

[0011] Furthermore, the drive assembly includes a power supply compartment, a battery, a motor, and a reducer. The power supply compartment is fixed to the outer casing, the battery is installed inside the power supply compartment, the battery is electrically connected to the motor, the drive end of the motor is connected to the reducer, and the reducer is connected to the ball screw.

[0012] Furthermore, a cover is fixedly provided at the rear end of the power compartment, and the cover, battery compartment, and motor are pressed together in sequence to form a sealed cavity.

[0013] Furthermore, a sealing ring is provided between the outer wall of the power supply compartment and the inner wall of the outer casing.

[0014] Furthermore, sealing rings are provided between the outer wall of the piston cylinder and the inner wall of the sampling cylinder, and between the outer wall of the balance piston and the inner wall of the sampling cylinder.

[0015] Furthermore, the sampling tube has an extended limiting step at the rear end, which is used for fixing and positioning by the step inside the outer shell.

[0016] Furthermore, the rear end of the motor is connected to the power supply compartment front end via a wire plug, and the front end of the motor is connected to the reducer via a threaded connection.

[0017] Furthermore, the balance piston is separated from the front end of the piston cylinder by a certain distance.

[0018] Furthermore, the first check valve, the second check valve, and the third check valve are remotely controlled from the ground.

[0019] Furthermore, the motor is directly powered by a battery and remotely controlled from the ground.

[0020] Furthermore, the piston cylinder cavity is connected to the ball screw via threads. When the ball screw rotates forward or backward, it drives the piston cylinder to perform linear reciprocating motion via the threads.

[0021] Furthermore, the cavity between the piston cylinder and the balance piston inside the sampling cylinder is filled with buffer solution and maintains a certain hydraulic pressure, while the cavity between the balance piston and the lower end of the sampling cylinder is not filled with liquid.

[0022] The beneficial effects of this invention are:

[0023] By applying the low-pollution formation fluid sampling technology and suction power device provided by this invention, the sampling chamber can be pre-flushed before suction operations, improving the accuracy and reliability of formation fluid property parameter assessment. The method of controlling the ball screw rotation with a DC motor to drive the piston ensures the reliability of the piston's action. Furthermore, the DC motor can rotate in both directions; when rotating forward, the piston draws in formation fluid, and when rotating in reverse, it discharges the formation fluid. With sufficient buffer solution, multiple operations can be performed, improving economic efficiency. Attached Figure Description

[0024] Figure 1 This is a simplified structural diagram of the present invention.

[0025] Figure 2 This is a schematic diagram showing the assembly of the present invention before it is lowered into the well.

[0026] Figure 3 This is a schematic diagram of the pre-rinsing state of the present invention.

[0027] Figure 4 This is a schematic diagram of the suction operation state of the present invention.

[0028] Figure 5 This is a schematic diagram of the state of the sampled fluid discharged according to the present invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0030] like Figure 1 The present invention consists of three parts: outer shell 1, suction power assembly and pre-rinsing mechanism assembly.

[0031] The suction power assembly consists of a retaining ring 2, a sealing ring 3, a battery compartment cover 20, a sealing ring 21, a battery compartment 4, a battery 5, a DC motor 6, a reducer 7, a bearing 8, a bearing support plate 9, a ball screw 11, a piston cylinder 12, and a sealing ring 13.

[0032] The pre-flushing mechanism assembly consists of a sampling cylinder 10, a balance piston 14, a sealing ring 15, a guide pipe 16, a check valve 17, a check valve 2 18, and a check valve 3 19.

[0033] The outer casing 1 fully accommodates the retaining ring 2, sealing ring 3, battery compartment cover 20, sealing ring 21, battery compartment 4, battery 5, DC motor 6, reducer 7, bearing 8, bearing support plate 9, ball screw 11, piston cylinder 12, sealing ring 13, sampling cylinder 10, balance piston 14, sealing ring 15, guide tube 16, one-way valve No. 1 17, one-way valve No. 2 18, and one-way valve No. 3 19.

[0034] The battery compartment 4, DC motor 6, reducer 7, and ball screw 11 are connected in sequence. The ball screw 11 is threadedly connected to the piston cylinder 12. The piston cylinder 12 is installed inside the sampling cylinder 10 and has a sealing ring 13 to ensure the sealing of the sampling cylinder 10. The sampling cylinder 10 is installed inside the outer casing 1 and is fixed and positioned by a step inside the outer casing 1. The battery 5 is installed inside the battery compartment 4, with a rigid wire plug at the front end and the rear end pressed by the battery compartment cover 20. The battery compartment cover 20 is threadedly connected to the battery compartment 4 and has a sealing ring 21 to seal the battery compartment 4. The rear end of the DC motor 6 is connected to the wire plug at the front end of the battery compartment 4, and the front end of the DC motor 6 is threadedly connected to the reducer 7. The rear end of the reducer 7 is threadedly connected to the ball screw 11 and is pressed against the upper end face of the bearing 8. The lower end face of the bearing 8 presses against the bearing support plate 9, and the lower end face of the bearing support plate 9 is pressed against the upper end face of the sampling cylinder 10. The retaining ring 2 presses against the battery compartment 4, thereby fixing the sealing ring 3, battery compartment cover 20, sealing ring 21, battery compartment 4, battery 5, DC motor 6, reducer 7, bearing 8, bearing support plate 9, ball screw 11, piston cylinder 12, sealing ring 13, and sampling cylinder 10.

[0035] A balance piston 14 is installed inside the sampling cylinder 10, a distance away from the piston cylinder 12. A sealing ring 13 is located around the circumference of the balance piston 14. Three guide tubes 16 are connected to the rear end of the sampling cylinder 10. Three one-way valves are connected to the three guide tubes 16: one-way valve 17, one-way valve 18, and one-way valve 19. One end of the uppermost guide tube 16 is connected to the lower middle part of the sampling cylinder 10, and the other end is connected to one-way valve 17, leading to the outside. The other two guide tubes 16 are connected to the rear end of the sampling cylinder 10 at one end, and to one-way valves 18 and 19 respectively, leading to the outside. One-way valve 17 operates from left to right, one-way valve 18 operates from left to right, and one-way valve 19 operates from right to left.

[0036] Check valves 17 (No. 1), 18 (No. 2), and 19 (No. 3) can all be remotely controlled from the ground. The DC motor 6 is directly powered by battery 5 and can be remotely controlled from the ground. A sealing ring 3 is installed on the battery compartment 4 to ensure the sealing of the DC motor 6 and the reducer 7. The ball screw 11 is fitted with a bearing 8 to ensure sufficiently low friction during rotation. The piston cylinder 12 is connected to the ball screw 11 via threads. When the ball screw 11 rotates forward or backward, the piston cylinder 12 is raised or lowered relative to the sampling cylinder 10 via the threads. The sampling cylinder 10 has a step inside; the piston cylinder 12 stops at the step.

[0037] like Figure 2 After the entire device is assembled, the cavity between the piston cylinder 12 and the balance piston 14 inside the sampling cylinder 10 is filled with buffer solution and maintains a certain hydraulic pressure. The cavity between the balance piston 14 and the lower end of the sampling cylinder 10 is not filled with liquid, and check valves 17, 18, and 19 are all closed.

[0038] like Figure 3 After the entire device is assembled, it is lowered to the bottom of the well. Before reaching the target sampling layer, check valves 17, 18, and 19 are all closed. When the target sampling layer is reached, check valves 18 and 19 open under surface control, allowing formation fluid to enter the cavity between the balance piston 14 and the lower end of the sampling cylinder 10. Because the cavity between the piston cylinder 12 and the balance piston 14 is filled with buffer solution, the high-pressure formation fluid will not violently push the balance piston 14, preventing it from colliding with the piston cylinder 12. The formation fluid flushes the cavity clean, ensuring that only the target sampling layer fluid remains inside. At this point, the pressure at both ends of the balance piston 14 reaches equilibrium.

[0039] like Figure 4 When the entire system begins suction operation, check valves 17 (No. 1) and 19 (No. 3) are fully opened under ground control, while check valve 18 (No. 2) is closed. Under ground control, DC motor 6 starts rotating, driving the ball screw to rotate. Through the threads on the ball screw, piston cylinder 12 is lifted, increasing the volume of the cavity between piston cylinder 12 and balance piston 14. Under external pressure, formation fluid enters the cavity between balance piston 14 and the lower end of sampling cylinder 10 through the guide pipe connected to check valve 19 (No. 3). Simultaneously, the buffer solution in the cavity between piston cylinder 12 and balance piston 14 is discharged through the guide pipe connected to check valve 17 (No. 1). After confirming that the obtained fluid has met the requirements, DC motor 6 stops rotating under ground control, and check valves 17 (No. 1), 18 (No. 2), and 19 (No. 3) close, ending the fluid suction operation.

[0040] like Figure 5If, during or after the entire pumping operation, the obtained formation fluid is deemed insufficient, the DC motor 6 can be reversed from the ground, closing check valve 17 and opening check valve 18. The reverse rotation of the DC motor 6 pushes down the piston cylinder 12, compressing the balance piston 14 and discharging the fluid from the cavity between the balance piston 14 and the lower end of the sampling cylinder 10, thus facilitating subsequent construction operations.

[0041] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A formation fluid low contamination sampling while drilling apparatus, comprising: The device comprises an outer shell, a sampling cylinder, a suction power assembly and a pre-flushing mechanism assembly. The outer shell is tubular, and the sampling cylinder is fixed in the middle section of the outer shell. The suction power assembly comprises a driving assembly, a ball screw and a piston cylinder. The driving assembly is fixed in the rear section of the outer shell. The driving assembly and the ball screw are drivingly connected. The ball screw and the piston cylinder are screw transmission connected.

2. The low contamination formation fluid sampling while drilling apparatus of claim 1, wherein, The piston cylinder is arranged in the middle rear section of the sampling cylinder.

3. The low contamination formation fluid sampling while drilling apparatus of claim 2, wherein, The piston cylinder and the sampling cylinder are slidingly and sealingly matched.

4. The low contamination formation fluid sampling while drilling apparatus of claim 3, wherein, The pre-flushing mechanism assembly comprises a balance piston, three flow guide pipes, a first one-way valve, a second one-way valve and a third one-way valve.

5. The low contamination formation fluid sampling while drilling apparatus of claim 4, wherein, The balance piston is arranged in the front section of the sampling cylinder and is slidingly and sealingly matched with the sampling cylinder.

6. The low contamination formation fluid sampling while drilling apparatus of claim 5, wherein, One of the three flow guide pipes is connected between the piston cylinder and the balance piston and is provided with the first one-way valve.

7. The low contamination formation fluid sampling while drilling apparatus of claim 6, wherein, The other two flow guide pipes are connected with the rear end of the sampling cylinder and are respectively provided with the second one-way valve and the third one-way valve.

8. The low contamination formation fluid sampling while drilling apparatus of claim 7, wherein, The front end of the uppermost flow guide pipe is connected with the middle lower part of the sampling cylinder, and the rear end thereof is connected with the first one-way valve and then connected to the outside.

9. A low contamination formation fluid sampling device while drilling according to any one of claims 2 to 8, wherein, The front ends of the other two flow guide pipes are connected with the rear end of the sampling cylinder.

10. The low contamination formation fluid sampling while drilling apparatus of any one of claims 2-8, wherein, The rear ends of the other two flow guide pipes are respectively connected with the second one-way valve and the third one-way valve and then connected to the outside. The first one-way valve is in a front-to-rear direction. The second one-way valve is in a front-to-rear direction. The third one-way valve is in a rear-to-front direction. The inner cavity of the piston cylinder is connected with the ball screw through threads. When the ball screw is rotated forward or reversely, the piston cylinder is driven to move linearly through the threads. The cavity between the piston cylinder and the balance piston in the sampling cylinder is filled with buffer liquid and maintains a certain hydraulic pressure. The cavity between the balance piston and the lower end of the sampling cylinder is not filled with liquid. The driving assembly comprises a power source compartment, a battery, a motor and a speed reducer. The power source compartment is fixed in the outer shell. The battery is arranged in the power source compartment. The battery is electrically connected with the motor. The driving end of the motor is connected with the speed reducer. The speed reducer is connected with the ball screw. The outer wall of the power source compartment and the inner wall of the outer shell are provided with a sealing ring. The outer wall of the piston cylinder and the inner wall of the sampling cylinder are provided with a sealing ring. The outer wall of the balance piston and the inner wall of the sampling cylinder are provided with a sealing ring. The rear end of the sampling cylinder is provided with an extended limiting step. The step in the inner part of the outer shell is used for fixing and positioning. The rear end of the motor is connected with the plug of the wire at the front end of the power source compartment. The front end of the motor is connected with the speed reducer through threads. The motor is directly powered by the battery and is remotely controlled from the ground. The first one-way valve, the second one-way valve and the third one-way valve are remotely controlled by switches from the ground.

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