A device for testing early hydration degree and interlayer channeling of cement slurry in situ

Abstract

This invention discloses an in-situ device for testing the early hydration degree and interlayer flow of cement slurry in well cementing. It comprises a wellbore simulation system, a circuit system, a pressure system, a temperature control system, and a control center. The wellbore simulation system includes an insulating rubber sleeve 1, a metal sleeve 3, and a simulated derrick 11, with the insulating rubber sleeve fixed inside the metal sleeve. The circuit system includes a ring electrode 2, a rod electrode 10, a protective resistor 13, a control power supply 14, an ammeter 15, and an on / off controller 16, which is connected to a computer. The pressure system includes a pressure sensor 4, an upper pressure relief valve 20, an upper pressure valve 21, a pressure pump 22, a lower pressure valve 23, and a lower pressure relief valve 25, with the pressure sensor located at the bottom of the outer wall of the metal sleeve. The temperature control system includes upper and lower heating jackets. The control center includes a computer 17 and a numerical display. This invention can monitor the flow of cement slurry as it transitions from a liquid to a solid state, optimize cement slurry formulation design, and improve cementing quality.

Description

Technical Field

[0001] This invention relates to a measuring device for simulating the early hydration degree and interlayer flow of cement slurry under different temperatures and pressures in oil and gas wells, applicable to the cementing field in oil and gas exploration and development. Background Technology

[0002] During oil and gas field development, cement slurry is injected into the annulus between the casing and the formation to protect and support the casing and to isolate oil, gas, and water layers. After injection, the cement slurry gradually transforms from a liquid to a solid state due to its own hydration reaction, thus providing support and isolation. During this process, the formation fluid, under pressure, continuously impacts the cement slurry. Initially, the cement slurry is liquid, and its annular liquid column exerts a certain pressure on the formation under gravity (i.e., hydrostatic pressure), which counteracts the formation pressure. As the cement slurry hydrates, a network structure continuously forms inside its liquid column. Eventually, at a certain point, the cement slurry completely loses its hydrostatic pressure; this process is called the weightlessness process of the cement slurry. During weightlessness, if the hydrostatic pressure drops below the formation pressure, the cement slurry will not have developed sufficient strength to resist the formation pressure. This will cause the formation fluid to enter the annulus and rise to the wellhead, resulting in an uncontrolled blowout. This not only wastes oil and gas resources but also damages the surface environment and may cause serious safety accidents.

[0003] Some scholars have studied the hydrostatic pressure of cement slurry columns and early hydration, as well as their interrelationship. The "Oil Well Cement Weight Loss and Gas-Liquid Channeling Simulation Test Device" (ZL200720149001) can test weight loss states under near-realistic conditions such as the width and narrowness of the annular space gaps, temperature differences, and well inclination. However, it ultimately obtains only the apparent results of weight loss, namely the changes in hydrostatic pressure, and does not characterize the specific properties of the cement slurry during the weight loss process, thus failing to provide in-situ analysis of the causes of weight loss.

[0004] This invention proposes an in-situ testing device for the early hydration degree and interlayer flow of cement slurry. It can simultaneously measure the early hydration degree of cement slurry and the hydrostatic column pressure and obtain the relationship between the two. It can also test the interlayer flow of cement slurry column, thereby optimizing the cement slurry formulation design and better solving the problems of gas and water flow during the cementing process. Summary of the Invention

[0005] The purpose of this invention is to provide an in-situ device for testing the early hydration degree and interlayer flow of cement slurry. This device can simulate the annulus conditions under different oil and gas well conditions, measure the resistivity of the annulus cement slurry in situ, characterize the relationship between its hydration degree and hydrostatic column pressure changes, and monitor the annulus flow of cement slurry as it changes from liquid to solid state, thereby optimizing the cement slurry formulation design and improving cementing quality.

[0006] To achieve the above technical objectives, the present invention adopts the following technical solution.

[0007] A device for in-situ testing of early hydration degree and interlayer flow of cement slurry in well cementing mainly consists of a wellbore simulation system, a current control system, a temperature control system, a pressure system, and a control center.

[0008] The wellbore simulation system includes an insulating rubber tube, a metal sleeve, and a simulated well frame.

[0009] The current control system includes a power supply, a resistor, an ammeter, an on / off controller, and a ring electrode. The on / off state of the circuit is controlled by a computer, and the values ​​of the current sensor are recorded.

[0010] The temperature control system includes temperature sensors and heating jackets to monitor the temperature at different locations. The entire heating system contains multiple heating jackets, and the heating time and temperature are controlled by a computer.

[0011] The pressure system includes a pressure sensor, a pressurizing pump, a pressurizing valve, and a pressure relief valve. The pressurizing pump simulates formation pressure and cementing control pressure.

[0012] The control center includes a digital display operator and a computer.

[0013] Current flow simulation devices cannot test for minute interlayer flows. Interlayer flows can cause oil and gas resources to flow into non-collected layers, leading to reduced well production efficiency and even safety accidents. This invention utilizes circuit elements to measure minute current changes from bottom to top to determine whether flow has occurred. Therefore, it can be used to simulate flow caused by formation pressure during cementing, and is particularly suitable for some interlayer flows. Current flow simulation devices only measure a single performance characteristic, while this invention can be used to study the hydration process of early cement slurry hydration, hydrostatic column pressure, and the relationship between the two.

[0014] Compared with the prior art, the present invention has the following beneficial effects: (1) The test is simple, and the data processing is all done by computer. Direct images and test results are obtained through the control center; (2) It has a wide range of applications and can monitor the hydration process, hydrostatic pressure and the relationship between the two of cement slurry from injection to solidification in one go. (3) The simulation is comprehensive and can simulate the actual downhole temperature, formation pressure, wellbore conditions and actual pressurization scheme; (4) It is highly practical and can simulate the interlayer flow of cement slurry based on the hydration conditions during the early hydration of cement slurry. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of a device for in-situ testing of the early hydration degree and interlayer flow of cement slurry in well cementing.

[0016] In the diagram: 1—Insulating rubber sleeve, 2—Ring electrode, 3—Metal sleeve, 4—Pressure sensor, 5—Lower insulating cover, 6—Lower sealing ring, 7—Upper sealing ring, 8—Upper insulating cover, 9—Upper heating sleeve, 10—Rod electrode, 11—Simulated derrick, 12—Lower heating sleeve, 13—Protective resistor, 14—Control power supply, 15—Precision ammeter, 16—On / off controller, 17—Computer, 18—Protective pipeline, 19—Cross-flow control valve, 20—Upper pressure relief valve, 21—Upper pressure valve, 22—Pressure pump, 23—Lower pressure valve, 24—Protective container, 25—Lower pressure relief valve. Detailed Implementation

[0017] The present invention will be further described below with reference to the accompanying drawings to enable those skilled in the art to understand the invention. However, it should be understood that the present invention is not limited to the specific embodiments described herein. For those skilled in the art, any modifications that fall within the spirit and scope of the invention as defined and determined by the appended claims are protected.

[0018] See Figure 1 .

[0019] A device for in-situ testing of early hydration degree and interlayer flow of cement slurry in well cementing consists of a wellbore simulation system, a circuit system, a pressure system, a temperature control system, and a control center.

[0020] The wellbore simulation system includes an insulating rubber tube 1, a metal sleeve 3, a lower insulating cover 5, a lower sealing ring 6, an upper sealing ring 7, an upper insulating cover 8, and a simulated derrick 11. The insulating rubber tube 1 is fixed at the center position inside the metal sleeve 3. The upper and lower ends of the insulating rubber tube are respectively provided with an upper insulating cover 8 and a lower insulating cover 5 containing a pressurized inlet. The upper and lower ends of the metal sleeve are respectively provided with an upper sealing ring 7 and a lower sealing ring 6. The metal sleeve 3 is fixed on the simulated derrick 11.

[0021] Furthermore, the metal sleeve 3 is composed of two semi-annular metal plates.

[0022] Furthermore, the metal sleeve 3 can be tilted at an angle to simulate the inclination angle of an actual wellbore.

[0023] The circuit system includes a ring electrode 2, a rod electrode 10, a protective resistor 13, a control power supply 14, a precision ammeter 15, and an on / off controller 16. One end of the rod electrode 10 enters the insulating rubber tube, and the other end is connected to the protective resistor 13, the control power supply 14, the precision ammeter 15, and the on / off controller 16 in sequence via wires. The ring electrode 2 is embedded in the inner wall of the insulating rubber tube and is connected to the on / off controller 16 via wires. The on / off controller is connected to a computer 17.

[0024] Furthermore, there are 3 to 7 ring electrodes 2, distributed at different positions on the inner wall of the insulating rubber tube. A single ring electrode, a rod electrode, a protective resistor, a control power supply, a precision ammeter, and a switching controller constitute a complete circuit.

[0025] Furthermore, the on / off controller is controlled by computer 17 to realize the switching of on / off states between different annular electrodes.

[0026] The pressure system includes a pressure sensor 4, an upper pressure relief valve 20, an upper pressure valve 21, a pressure pump 22, a lower pressure valve 23, and a lower pressure relief valve 25. The pressure pump 22 pressurizes the insulating rubber cylinder through the pressure inlets of the upper insulating cover 8 and the lower insulating cover 5 via connecting pipelines. The connecting pipelines are equipped with the upper pressure valve 21, the lower pressure valve 23, the upper pressure relief valve 20, and the lower pressure relief valve 25. The pressure in the container and pipeline is vented through the upper and lower pressure relief valves. The pressure sensor 4 is located at the bottom of the outer wall of the metal sleeve and is connected to the computer 17.

[0027] Furthermore, the pressurization inlet of the lower insulating cover 5 is connected to the protective container 24 through the protective pipeline 18, the protective container is connected to the pressurization pump 22, and a crossflow control valve 19 is installed on the protective pipeline.

[0028] Furthermore, the protective pipeline 18 is a transparent plastic pipeline, and water is added to the protective container 24 in advance to prevent cement slurry from entering the pressure pump.

[0029] The temperature control system includes an upper heating jacket 9 and a lower heating jacket 12, which are connected to a computer 17 to control the heating temperature and heating time of the heating jackets.

[0030] The control center includes a computer 17 and an attached numerical display.

[0031] The computer 17 controls the voltage release time and magnitude of the power supply 14, controls the on / off status of the on / off controller 16, controls the heating time and temperature of the upper heating jacket 9 and the lower heating jacket 12, controls the pressure of the pressurizing pump 22, and simultaneously records the value of the precision ammeter 15 and the on / off status of the on / off controller 16, analyzes and records the current of different annular electrodes 2, and records the values ​​of the pressurizing pump 22 and the pressure sensor 4.

[0032] The method for in-situ testing of early hydration degree and interlayer flow of cement slurry using the above-mentioned device is as follows: (1) Add a small amount of drilling fluid to the insulating rubber tube so that the drilling fluid is evenly covered on the inner wall of the insulating rubber tube; (2) Fix the insulating rubber tube in the center position inside the metal sleeve, and adjust the metal sleeve to the required angle; (3) Pour the prepared cement slurry into the insulating rubber tube, and assemble the insulating cap and sealing ring; (4) Set the required temperature and pressure using the upper and lower heating jackets and the pressure pump; (5) Set the cycle of the on / off controller and the voltage of the power supply via computer; (6) Close the crossflow control valve, measure the current value at different positions through the ring electrode, convert it into resistivity through computer, and obtain the early hydration degree of cement slurry. Obtain its hydrostatic pressure through the value measured by the pressure sensor. (7) Open the crossflow control valve and apply simulated formation pressure to the bottom of the cement slurry through the pressurization pump. Observe the current value measured by the annular electrode at different positions. When the current value changes abruptly, it indicates that crossflow has occurred at this position.

[0033] The above description is merely an embodiment of the present invention. It should be noted that those skilled in the art can make improvements without departing from the principle of the present invention, and all such improvements fall within the protection scope of the claims of the present invention.

Claims

1. A device for in-situ testing of early hydration degree and interlayer flow of cement slurry, comprising a wellbore simulation system, a circuit system, a pressure system, a temperature control system, and a control center, characterized in that, The wellbore simulation system includes an insulating rubber tube (1), a metal sleeve (3), a lower insulating cover (5), a lower sealing ring (6), an upper sealing ring (7), an upper insulating cover (8), and a simulated well frame (11). The insulating rubber tube is fixed in the center of the metal sleeve. The upper and lower ends of the insulating rubber tube are respectively provided with an upper insulating cover and a lower insulating cover containing a pressurization inlet. The pressurization inlet of the lower insulating cover is connected to a protective container (24) through a protective pipeline (18). The protective container is connected to a pressurization pump (22). A crossflow control valve (19) is provided on the protective pipeline. The metal sleeve is fixed on the simulated well frame. The upper and lower ends of the metal sleeve are respectively provided with an upper sealing ring and a lower sealing ring. The circuit system includes a ring electrode (2), a rod electrode (10), a protective resistor (13), a control power supply (14), a precision ammeter (15), and an on / off controller (16). One end of the rod electrode enters the insulating rubber tube, and the other end... The protective resistor, control power supply, precision ammeter and on / off controller are connected in sequence by wires. The ring electrode is embedded in the inner wall of the insulating rubber tube and connected to the on / off controller by wires. The on / off controller is connected to the computer (17). The pressure system includes a pressure sensor (4), an upper pressure relief valve (20), an upper pressure valve (21), a pressure pump (22), a lower pressure valve (23) and a lower pressure relief valve (25). The pressure pump pressurizes the insulating rubber tube through the pressure inlets of the upper and lower insulating covers via connecting pipelines. The connecting pipelines are equipped with an upper pressure valve, a lower pressure valve, an upper pressure relief valve and a lower pressure relief valve. The pressure sensor is located at the bottom of the outer wall of the metal sleeve and is connected to the computer (17). The temperature control system includes an upper heating sleeve (9) and a lower heating sleeve (12). The upper heating sleeve and the lower heating sleeve are connected to the computer (17). The control center includes the computer (17) and an attached numerical display.

2. The device for in-situ testing of early hydration degree and interlayer flow of cement slurry as described in claim 1, characterized in that, The metal sleeve (3) is composed of two semi-annular metal plates.

3. The device for in-situ testing of early hydration degree and interlayer flow of cement slurry as described in claim 1, characterized in that, The metal sleeve (3) simulates the inclination angle of the actual wellbore by setting an inclination angle.

4. The device for in-situ testing of early hydration degree and interlayer flow of cement slurry as described in claim 1, characterized in that, There are 3 to 7 ring electrodes (2) distributed at different positions on the inner wall of the insulating rubber tube. A single ring electrode, a rod electrode, a protective resistor, a control power supply, a precision ammeter and a switching controller constitute a complete circuit.

5. The device for in-situ testing of early hydration degree and interlayer flow of cement slurry as described in claim 1, characterized in that, The on / off controller is computer-controlled to switch between different annular electrodes.

6. The device for in-situ testing of early hydration degree and interlayer flow of cement slurry as described in claim 1, characterized in that, The protective pipeline (18) is a transparent plastic pipeline. Water is added to the protective container (24) in advance to prevent cement slurry from entering the pressurizing pump.

7. A method for in-situ testing of early hydration degree and interlayer flow of cement slurry using the apparatus described in any one of claims 1-6, comprising the following steps in sequence: (1) Add a small amount of drilling fluid to the insulating rubber tube so that the drilling fluid is evenly covered on the inner wall of the insulating rubber tube; (2) Fix the insulating rubber tube in the center position inside the metal sleeve, and adjust the metal sleeve to the required angle; (3) Pour the prepared cement slurry into the insulating rubber tube, and assemble the insulating cap and sealing ring; (4) Set the required temperature and pressure using the upper and lower heating jackets and the pressure pump; (5) Set the cycle of the on / off controller and the voltage of the power supply via computer; (6) Close the crossflow control valve, measure the current value at different positions through the ring electrode, convert it into resistivity through computer, and obtain the early hydration degree of cement slurry. Obtain its hydrostatic pressure through the value measured by the pressure sensor. (7) Open the crossflow control valve and apply simulated formation pressure to the bottom of the cement slurry through the pressurization pump. Observe the current value measured by the annular electrode at different positions. When the current value changes abruptly, it indicates that crossflow has occurred at this position.

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