Formation pressure measuring pipe column

Abstract

The utility model relates to the technical field of in-well pressure measurement, in particular to a formation pressure measuring pipe column which comprises an oil pipe, a pressure measuring element, a packer and a liquid extractor, the packer is arranged above a formation to seal the annulus between the pressure measuring pipe column and a shaft, the liquid extractor comprises a cylinder body and a piston, the cylinder body is connected with the oil pipe, and the piston is connected with the oil pipe. The piston divides an inner cavity of the pressure measuring pipe column into an upper pipe cavity and a lower pipe cavity, the piston and the cylinder body move relatively to be used for sucking well killing fluid in the lower pipe cavity of the pressure measuring pipe column so that formation fluid can flow into a shaft from a formation, and the pressure of the lower pipe cavity of the pressure measuring pipe column and the pressure of the shaft below the packer are equal to the pressure of the formation. The liquid column pressure of the well killing fluid in the upper pipe cavity and the space above the packer is separated from the pressure of the lower pipe cavity and the space below the packer, the formation pressure can be obtained by measuring the pressure of the lower pipe cavity of the pressure measuring pipe column or the pressure of a shaft below the packer, the influence of the well killing fluid in the shaft is avoided, and the formation pressure measuring accuracy is improved.

Description

Technical Field

[0001] This utility model relates to the field of well pressure measurement technology, specifically to formation pressure measurement tubing. Background Technology

[0002] In the process of oilfield development, especially in multi-layered oilfields, there are contradictions between layers and within layers. It is usually necessary to analyze the reservoir characteristics based on the changes in reservoir pressure to provide a strong basis for the next stage of reservoir development and transformation and the long-term water control and oil production of the oilfield. Obtaining accurate formation pressure data is an important condition for ensuring the safety of oil well production and increasing oil well output.

[0003] Currently, formation pressure measurement typically involves lowering a pressure gauge into the wellbore at the location corresponding to the oil layer. The gauge is lowered into the wellbore using tubing, forming the pressure measurement string, with the gauge acting as the pressure measuring element. For post-drilling formation pressure testing, kill fluid is often injected into the wellbore. For wellbores with kill fluid, this conventional method is relatively accurate for formations with high permeability and minimal drilling mud contamination of the oil layer. However, for formations with low permeability and significant drilling mud contamination, the presence of kill fluid in the wellbore, combined with the formation initiation pressure being much higher than the formation pressure, results in a higher wellbore pressure than the formation pressure. This leads to inflated pressure measurements within the wellbore. Utility Model Content

[0004] The purpose of this invention is to provide a formation pressure testing string to solve the problem that current formation pressure testing strings are easily affected by the well control fluid when used in wellbore containing well control fluid for formation pressure testing, resulting in inaccurate pressure measurement data.

[0005] The technical solution of this utility model's formation piezometric testing string is as follows:

[0006] The formation pressure testing string includes tubing and a pressure measuring element, as well as a packer and a pump. The packer is used to seal the annulus between the pressure testing string and the wellbore above the formation to be tested. The pump includes a cylinder and a piston disposed within the cylinder. The cylinder is connected to the tubing. The piston divides the inner cavity of the pressure testing string into an upper cavity and a lower cavity. The piston can move upward relative to the cylinder or the cylinder can move downward relative to the piston to pump kill fluid from the lower cavity of the pressure testing string, allowing formation fluid to flow from the formation into the wellbore. The pressure measuring element is disposed in the portion of the pressure testing string that forms the lower cavity.

[0007] Furthermore, the pump includes an outer cylinder and an inner tube. The outer cylinder forms a cylinder body, and a piston is located at the upper end of the inner tube. The lower end of the outer cylinder is provided with an inner ring platform, and the inner tube passes through the central hole of the inner ring platform. The piston is located above the inner ring platform and has an end face facing the inner ring platform to form a negative pressure suction chamber between the piston and the inner ring platform when the piston moves relative to the cylinder body. The inner tube is provided with a communication hole below the piston for communicating with the negative pressure suction chamber. The upper cavity includes the space in the outer cylinder located above the piston, and the lower cavity includes the space in the inner tube located below the piston.

[0008] Furthermore, the inner tube has an upward-facing abutment surface below the inner ring platform, and a spring is fitted on the outside of the inner tube. The upper end of the spring abuts against the lower end face of the inner ring platform, and the lower end abuts against the upward-facing abutment surface.

[0009] Furthermore, the inner tube includes a main tube body, a piston is disposed at the upper end of the main tube body, and a lower connector is provided at the lower end of the main tube body, with the upward-facing abutment surface disposed on the lower connector.

[0010] Furthermore, the outer cylinder includes a main cylinder body, and a sealing ring is connected to the inner wall at the lower end of the main cylinder body, the sealing ring forming the inner ring platform.

[0011] Furthermore, the piston includes a piston body that slides with the cylinder body, the piston body having a central hole that connects the upper cavity and the lower cavity, and a sealing body movably provided on the piston body for blocking the central hole to separate the upper cavity and the lower cavity.

[0012] Furthermore, the sealing body is a sphere, and the piston body is provided with a sealing surface that seals with the sphere.

[0013] Furthermore, the oil pipe includes a lower connecting pipe connected to the lower end of the pump, and the lower connecting pipe is equipped with a check valve structure for upward flow of liquid.

[0014] Furthermore, the oil pipe includes a lower connecting pipe connected to the lower end of the pump, the lower lumen includes the inner cavity of the lower connecting pipe, a plug is provided on the lower side of the lower connecting pipe, and the pressure measuring element is supported on the plug.

[0015] The beneficial effects of this invention's formation pressure testing string: This invention improves upon existing formation pressure testing strings by using a packer to seal the annulus between the pressure testing string and the wellbore, and using a piston in the pump to separate the upper and lower cavities of the pressure testing string. This allows the lower cavity to communicate with the space below the packer and the formation, while the upper cavity and the space above the packer are isolated from the formation. The relative movement of the piston and cylinder increases the volume of the lower cavity of the pressure testing string, thereby allowing for the pumping of the lower part of the pressure testing string. The kill fluid inside the chamber allows formation fluid to flow into the wellbore under suction. The pressure in the lower part of the test string and the wellbore below the packer is equal to the formation pressure. However, the pressure of the kill fluid column in the upper part of the chamber and the space above the packer is isolated from the pressure in the lower part of the chamber and the space below the packer. The formation pressure can be obtained by measuring the pressure in the lower part of the test string or the pressure in the wellbore below the packer. This avoids the influence of the kill fluid inside the wellbore and improves the accuracy of formation pressure measurement. It is suitable for performing formation pressure measurement in wellbores filled with kill fluid. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of an embodiment of the formation piezometric test string of this utility model;

[0017] Figure 2 for Figure 1 A schematic diagram of the structure of the liquid extractor in the diagram;

[0018] Figure 3 for Figure 2 A schematic diagram of the partial structure at the piston.

[0019] In the diagram: 101, upper connecting pipe; 102, pump; 103, packer; 104, second valve ball; 105, pressure measuring element; 106, screen tube; 107, plug; 108, lower connecting pipe; 200, sleeve; 300, upper oil sleeve annulus; 400, upper formation; 500, lower formation; 600, lower oil sleeve annulus; 1, upper connector; 2, first sealing ring; 3, main cylinder; 4, first valve ball; 5, piston body; 6, second sealing ring; 7, connecting hole; 8, sealing ring; 9, third sealing ring; 10, main pipe body; 11, spring; 12, lower connector. Detailed Implementation

[0020] This invention relates to a formation pressure testing string that uses a packer to seal the annulus between the testing string and the wellbore. A piston in the pump separates the upper and lower cavities of the testing string, allowing the lower cavity to communicate with the space below the packer and the formation, while the upper cavity and the space above the packer are isolated from the formation. The relative movement of the piston and cylinder increases the volume of the lower cavity, thereby drawing in kill fluid from the lower cavity and allowing formation fluid to be pumped out. Under the action of suction force, the fluid flows into the wellbore. The pressure in the lower part of the pressure measuring string and the wellbore pressure below the packer is equal to the formation pressure. However, the pressure of the kill fluid column in the upper part of the string and the space above the packer is isolated from the pressure in the lower part of the string and the space below the packer. The formation pressure can be obtained by measuring the pressure in the lower part of the pressure measuring string or the pressure in the wellbore below the packer. This avoids the influence of the kill fluid in the wellbore and improves the accuracy of formation pressure measurement. It is suitable for performing formation pressure measurement in wellbores filled with kill fluid.

[0021] An embodiment of the formation piezometric string of this utility model:

[0022] like Figure 1 , Figure 2 and Figure 3 As shown, the formation pressure testing string is used to be lowered into the wellbore to measure the pressure of the formation to be tested. The formation consists of an upper formation 400 and a lower formation 500. In this embodiment, the formation to be tested is the lower formation 500. A casing 200 is located inside the wellbore, forming an annulus between the casing 200 and the formation pressure testing string.

[0023] The formation pressure testing string includes tubing, a pressure measuring element 105, a packer 103, and a pump 102. The tubing includes an upper connecting pipe 101 and a lower connecting pipe 108. The pump 102 is located above the packer 103. The lower end of the upper connecting pipe 101 is connected to the pump 102. The upper end of the lower connecting pipe 108 is connected to the pump 102, and the lower end is connected to a screen tube 106. A plug 107 is connected to the lower end of the screen tube 106. The screen tube 106 is positioned directly opposite the middle of the lower formation 500 to allow formation fluid to flow in. The pressure measuring element 105 is located inside the screen tube 106 and supported on the plug 107 for measuring formation fluid pressure.

[0024] The pump 102 includes an outer cylinder and an inner tube. The outer cylinder includes a main body 3, with an upper connector 1 at the upper end and a sealing ring 8 at the lower end. The inner tube includes a main body 10, with a piston at the upper end and a lower connector 12 at the lower end. The piston includes a piston body 5 and a first valve ball 4. The upper connector 1 is connected to the upper connecting pipe 101, and the lower connector 12 is connected to the lower connecting pipe 108. The lower connecting pipe 108 is connected to a packer 103. The packer 103 is a hydraulically seated bidirectional slip packer. The packer 103 is used to seal the annulus between the pressure testing string and the wellbore above the formation to be tested. The distance between the packer 103 and the formation to be tested is no more than 10m. The annulus above the packer 103 is the upper sleeve annulus 300, and the annulus below the packer 103 is the lower sleeve annulus 600. The outer cylinder forms the cylinder body, and the piston is located inside the main cylinder body 3 of the outer cylinder. The inner cavity of the pressure measuring string includes the inner cavity of the pump 102 and the inner cavity of the tubing. The piston divides the inner cavity of the pressure measuring string into an upper cavity and a lower cavity. The lower cavity communicates with the space below the packer 103 and the formation. The cylinder body can move downward relative to the piston to draw the kill fluid in the lower cavity of the pressure measuring string so that the formation fluid flows from the formation into the wellbore. The pressure measuring element 105 is set in the lower cavity to measure the pressure in the lower cavity and thus obtain the formation pressure.

[0025] The upper connector 1 has a through-hole at the top and bottom. The upper end of the upper connector 1 has an internal thread for connection with the upper connecting pipe 101. The lower end of the upper connector 1 has an external thread and a sealing ring mounting groove. The upper end of the main cylinder 3 has an internal thread for threaded connection with the lower end of the upper connector 1. A first sealing ring 2 is provided in the sealing ring mounting groove at the lower end of the upper connector 1 to ensure a sealed connection between the upper connector 1 and the main cylinder 3. The upper connector 1, with its sealed threaded connection to the main cylinder 3, facilitates the adaptation of the upper connecting pipe 101 for connecting oil pipes.

[0026] The inner wall of the main cylinder 3 is smooth, and the lower end of the main cylinder 3 is provided with an internal thread. The sealing ring 8 is provided with an external thread. The sealing ring 8 is threadedly connected to the lower end of the main cylinder 3 and located inside the main cylinder 3. The sealing ring 8 seals with the main cylinder 3 and forms an inner ring platform of the outer cylinder opposite to the piston. The inner circumferential surface of the sealing ring 8 is provided with two sealing ring mounting grooves, and a third sealing ring 9 is installed in the sealing ring mounting grooves to form a seal on the outer circumferential surface of the main cylinder 10.

[0027] The main body 10 has an external thread at its upper end, and the piston body 5 has a through-hole. The through-hole of the piston body 5 includes an upper conical section and a lower connecting section. The lower connecting section has an internal thread to connect the piston body 5 to the upper end of the main body 10. The conical surface of the upper conical section forms a valve seat, which can block the through-hole of the piston body 5 when the first valve ball 4 falls on the valve seat. The through-hole of the piston body 5 forms a through hole that connects the upper and lower cavities of the test tube. The outer diameter of the piston body 5 is adapted to the inner diameter of the main cylinder 3 to facilitate relative sliding between the piston and the main cylinder 3. Two sealing ring mounting grooves are provided on the outer circumferential surface of the piston body 5, and a second sealing ring 6 is installed in the sealing ring mounting groove to form a seal between the outer circumferential surface of the piston body 5 and the inner circumferential surface of the main cylinder 3.

[0028] The main pipe body 10 passes through the central hole of the sealing ring 8. When the outer cylinder slides downward relative to the inner pipe, the sealing ring 8 and the main pipe body 10 are sealed by the third sealing ring 9, and the piston body 5 and the main cylinder body 3 are sealed by the second sealing ring 6. The lower end of the main pipe body 10 is provided with an external thread, and the lower connector 12 has a central hole that runs vertically through it. The upper end of the lower connector 12 is provided with an internal thread for threaded connection with the lower end of the main pipe body 10, and the lower end of the lower connector 12 is provided with an external thread for connection with the lower connecting pipe 108 of the oil pipe. A spring 11 is fitted on the outer side of the main pipe body 10. The spring 11 is a compression spring and is located between the sealing ring 8 and the lower connector 12. The upper end of the spring 11 abuts against the lower end face of the sealing ring 8, and the lower end abuts against the upper end face of the lower connector 12. The upper end face of the lower connector 12 forms an upward abutment surface, which facilitates the installation of the spring 11. Under the elastic force of spring 11, the lower end face of piston body 5 can be pressed against the upper end face of sealing ring 8 without lowering the outer cylinder, thus preventing the inner tube from moving relative to the outer cylinder during the process of lowering the test tube into the well.

[0029] The lower end face of the piston body 5 faces the sealing ring 8. When the piston body 5 moves relative to the main cylinder 3, the piston body 5 and the sealing ring 8 separate to form a negative pressure suction chamber between them. The negative pressure suction chamber is an annular cavity formed by the piston body 5, the sealing ring 8, the main cylinder 3, and the main pipe body 10. A connecting hole 7 is provided on the main pipe body 10 below and adjacent to the piston body 5 for communicating with the negative pressure suction chamber. The connecting hole 7 connects the inner cavity of the main pipe body 10 with the negative pressure suction chamber. The inner cavity of the main pipe body 10 has a space located below the piston. The upper cavity of the test string includes the space of the outer cylinder above the piston and the inner cavity of the upper connecting pipe 101 of the tubing. The lower cavity includes the space of the inner tube below the piston and the inner cavity of the lower connecting pipe 108 of the tubing. When the first valve ball 4 has not fallen onto the valve seat, the central hole of the piston body 5 can connect the upper and lower cavities to facilitate the lowering of the test string into the wellbore. The first valve ball 4 constitutes a sealing body used to seal the central hole of the piston body 5 to separate the upper and lower cavities. The sealing body is a ball, and the upper conical hole section of the piston body 5 constitutes a sealing surface that seals with the ball. This can separate the liquid column in the upper cavity of the test tube from the space below, preventing the pressure of the upper liquid column from affecting the formation pressure measurement.

[0030] In operation, the first valve ball 4 is not lowered into the well along with the pressure testing string. After the pressure testing string is lowered into the wellbore and positioned, the packer 103 sets above the formation, and then the first valve ball 4 is dropped. After the first valve ball 4 falls to the valve seat, the tubing continues to be lowered. The upper tubing of the pump 102 moves down along with the outer cylinder. Under the fixing action of the packer 103, the inner tube remains stationary. The sealing ring 8 compresses the spring 11 downward and separates from the piston. The annular volume between the outer cylinder and the inner tube between the sealing ring 8 and the piston increases, forming a negative pressure suction chamber. The connecting hole 7 connects the negative pressure suction chamber to the lower tubing below the piston. The packer 103 can extract fluid from the formation below it. After the formation fluid flows into the wellbore from the formation, the well is shut in. This makes the pressure in the lower part of the wellbore equal to the formation pressure. Furthermore, since the first valve ball 4 and the valve seat at the piston of the pump 102 form a one-way valve structure, the pressure of the liquid column in the upper cavity is isolated from the pressure in the lower cavity. The pressure measuring element 105 is installed in the lower connecting pipe 108 and can measure the pressure in the lower cavity. The lower cavity is connected to the formation, thereby obtaining the formation pressure and avoiding the influence of the well-pressurizing fluid in the wellbore on the formation pressure, thus improving the accuracy of formation pressure measurement.

[0031] The lower connecting pipe 108 is also provided with a one-way valve structure for the upward flow of liquid. The one-way valve structure includes a ball seat fixed on the inner wall of the lower connecting pipe 108 and a second valve ball 104. The ball seat is below the packer 103 and above the screen pipe 106. By utilizing the check valve structure within the pump 102 in conjunction with the check valve structure within the lower connecting pipe 108, the tubing string can be raised and lowered multiple times for pumping. After the first lowering of the tubing string to move the outer cylinder of the pump 102 downwards for pumping, the tubing string can be raised again to move the outer cylinder of the pump 102 upwards (the raising distance is less than the original lowering distance). During the raising, the piston remains stationary, and the sealing ring 8 moves upwards. The volume of the annulus between the sealing ring 8 and the piston decreases. Due to the presence of the check valve structure within the lower connecting pipe 108, the liquid pressure in the annulus between the sealing ring 8 and the piston increases. Through the connecting hole 7, the first valve ball 4 is pushed open and the fluid is discharged into the upper tubing of the pump 102. Lowering the tubing string again allows for pumping, which helps ensure that formation fluid enters the wellbore.

[0032] In this embodiment, the formation pressure testing string is used for pressure testing of the lower formation. In other embodiments, it can also be used for combined well testing, with the packer set above the upper formation.

[0033] In other embodiments, the cylinder of the pump can also be fixedly connected to the lower connecting pipe, and a sucker rod is connected above the piston. The sucker rod drives the piston to move upward relative to the cylinder, thereby sucking up the kill fluid in the lower part of the pipe below the piston.

[0034] In other embodiments, a sealing cap can be hinged to the piston body. The sealing cap can be flipped upward to open the central hole of the piston body and seal the central hole when it is on the piston body. The sealing cap constitutes a sealing body.

[0035] In other embodiments, the spring may be omitted, and the sealing ring may be pre-fixed to the main body by a shear pin. When the outer cylinder is lowered, the shear pin is cut off, causing the outer cylinder to move lower relative to the piston.

[0036] In other embodiments, a ring platform is integrally provided on the outer peripheral surface of the main body, and an upward abutment surface is provided on the ring platform.

[0037] In other embodiments, the main cylinder and the sealing ring can also be integrally formed.

[0038] In other embodiments, the upper connector may be omitted, and the main cylinder may be directly threaded to the upper connecting pipe.

[0039] In other embodiments, the pressure measuring element can also be installed on the outer wall of the lower connecting pipe to measure the wellbore pressure below the packer, that is, the pressure of the lower annulus.

[0040] In other embodiments, the check valve structure in the lower connecting pipe can be omitted, which is suitable for situations where only one pumping operation is required.

[0041] Finally, it should be noted that the above description is only a preferred embodiment of this utility model and is not intended to limit this utility model. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still make modifications to the technical solutions described in the foregoing embodiments without creative effort, or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A formation pressure testing string, comprising tubing and pressure measuring elements, characterized in that, It also includes a packer and a pump. The packer is used to seal the annulus between the pressure testing string and the wellbore above the formation to be tested. The pump includes a cylinder and a piston disposed in the cylinder. The cylinder is connected to the tubing. The piston divides the inner cavity of the pressure testing string into an upper cavity and a lower cavity. The piston can move upward relative to the cylinder or the cylinder can move downward relative to the piston to pump kill fluid from the lower cavity of the pressure testing string, so that formation fluid flows from the formation into the wellbore. The pressure measuring element is disposed in the part of the pressure testing string that forms the lower cavity.

2. The formation piezometric string according to claim 1, characterized in that, The pump includes an outer cylinder and an inner tube. The outer cylinder forms a cylinder body. A piston is located at the upper end of the inner tube. An inner ring platform is provided at the lower end of the outer cylinder. The inner tube passes through the central hole of the inner ring platform. The piston is located above the inner ring platform and has an end face facing the inner ring platform to form a negative pressure suction chamber between the piston and the inner ring platform when the piston moves relative to the cylinder body. A communication hole is provided on the inner tube below the piston for communicating with the negative pressure suction chamber. The upper cavity includes the space in the outer cylinder above the piston, and the lower cavity includes the space in the inner tube below the piston.

3. The formation piezometric string according to claim 2, characterized in that, The inner tube has an upward-facing abutment surface below the inner ring platform. A spring is fitted on the outside of the inner tube, with the upper end of the spring abutting against the lower end face of the inner ring platform and the lower end abutting against the upward-facing abutment surface.

4. The formation piezometric string according to claim 3, characterized in that, The inner tube includes a main body, a piston is disposed at the upper end of the main body, and a lower connector is provided at the lower end of the main body, with the upward-facing abutment surface disposed on the lower connector.

5. The formation piezometric string according to claim 2, 3, or 4, characterized in that, The outer cylinder includes a main cylinder body, and a sealing ring is connected to the inner wall at the lower end of the main cylinder body. The sealing ring constitutes the inner ring platform.

6. The formation piezometric string according to any one of claims 1-4, characterized in that, The piston includes a piston body that slides with the cylinder. The piston body has a through hole that connects the upper cavity and the lower cavity. A sealing body is movably provided on the piston body for sealing the through hole to separate the upper cavity and the lower cavity.

7. The formation piezometric string according to claim 6, characterized in that, The sealing body is a sphere, and the piston body is provided with a sealing surface that seals with the sphere.

8. The formation piezometric string according to claim 6, characterized in that, The oil pipe includes a lower connecting pipe connected to the lower end of the pump, and the lower connecting pipe is equipped with a check valve structure for upward flow of liquid.

9. The formation piezometric string according to any one of claims 1-4, characterized in that, The tubing includes a lower connecting pipe connected to the lower end of the pump, the lower lumen includes the inner cavity of the lower connecting pipe, a plug is provided on the lower side of the lower connecting pipe, and the pressure measuring element is supported on the plug.

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