CN116411936A - A device and method for evaluating the integrity of an irregular wellbore cement sheath seal - Google Patents

Abstract

The invention provides an irregular wellbore cement sheath seal integrity evaluation device and method, which can significantly improve the accuracy of the cement sheath seal integrity evaluation, has good sealing performance, and at the same time, the simulation and analysis results are closer to real working conditions. It includes a simulation device and a control device; the simulation device includes a rock core, a cement sheath and a casing, an irregular wellbore is opened in the rock core, a casing is arranged in the irregular wellbore, and a hole formed between the irregular wellbore and the casing Cement slurry is injected into the annulus to form a cement sheath; the control device includes a high-temperature autoclave and a hydraulic control device, and the high-temperature autoclave includes a high-temperature autoclave cover and a kettle body; during evaluation, the simulation device is installed in the still body of the high-temperature autoclave , multiple sets of pressure plates are arranged on the periphery of the rock core, a hydraulic chamber is formed between the pressure plates and the inner wall of the high-temperature autoclave, and the hydraulic chamber is connected with the output end of the hydraulic control device.

Description

A device and method for evaluating the integrity of an irregular wellbore cement sheath seal

technical field

The invention relates to the technical field of oil and gas drilling, in particular to a device and method for evaluating the integrity of cement sheath seals in irregular well holes.

Background technique

The sealing integrity of the cement sheath is an important part of the wellbore integrity. Simulating the sealing integrity of the cement sheath under different working conditions by means of experiments is one of the hotspots in the study of wellbore integrity at present. Due to the limitation of experimental conditions, the current experimental devices on the sealing integrity of the cement sheath are too ideal, and can only simulate the sealing integrity of the cement sheath under conventional parameters such as temperature, pressure, cement sheath (uniform cylinder) performance and thickness, etc. However, under actual working conditions, the wellbore is not a uniform round hole, but mostly a spiral or wellbore with a variable diameter, so the cement sheath formed by the cement slurry in the casing-borehole annulus is no longer uniform cylinder. There is a big difference in the sealing integrity of the cement sheath between the irregular wellbore and the regular wellbore. On the other hand, the current relevant experimental devices mostly use steel wellbore to simulate the formation, which is quite different from the cement sheath-formation bonding surface and in-situ stress under actual working conditions.

The cement sheath seal integrity evaluation means in the prior art, such as the simulated test device disclosed in CN104153760A oil and gas well cement sheath seal characteristic simulation test device and experimental method, the sealing performance is not good enough, mainly because the pressure plate used with different sizes of casing and the simulation test device. The connecting structure between the upper kettle cover cannot withstand too much pressure difference, so the predetermined goal can only be achieved to a certain extent; in addition, indirect measurement data (such as CN201610983232.2, etc.) Visually reflect the cement sheath interface damage and the damage status of the body.

Contents of the invention

In order to solve the problems existing in the prior art, the present invention provides an irregular wellbore cement sheath seal integrity evaluation device and method, which can significantly improve the accuracy of cement sheath seal integrity evaluation, good sealing performance, and simultaneous simulation and analysis results closer to the real working conditions.

To achieve the above object, the present invention provides the following technical solutions:

An irregular wellbore cement sheath seal integrity evaluation device, including a simulation device and a control device;

The simulation device includes a core, a cement sheath and a casing. An irregular wellbore is opened in the rock core, and a casing is arranged in the irregular wellbore. Cement slurry is injected into the annular space formed between the irregular wellbore and the casing to form a cement sheath;

The control device includes a high-temperature autoclave and a hydraulic control device, and the high-temperature autoclave includes a high-temperature autoclave cover and a still body;

During the evaluation, the simulation device is installed in the body of the high-temperature autoclave, and multiple groups of pressure plates are arranged on the periphery of the rock core. A hydraulic cavity is formed between the pressure plate and the inner wall of the high-temperature autoclave. The hydraulic cavity and the hydraulic control device output connection.

Preferably, the shape and size of the irregular wellbore are determined according to the size of different drill bits and different drilling depths.

Preferably, four sets of pressure plates are arranged on the periphery of the core to form four sets of hydraulic chambers.

Preferably, the output ends of the hydraulic control device are respectively connected to four sets of hydraulic chambers and bushings for controlling the pressure inside the hydraulic chambers and bushings.

Preferably, a pressure sensor is provided on the outer wall of the rock core, and the pressure sensor is connected to the input end of the hydraulic control device.

Preferably, a temperature control device and a heating insulation jacket are also included;

The heating and insulating jacket is arranged between the inner wall of the kettle and the hydraulic cavity, and the heating and insulating jacket is connected with the output end of the temperature control device.

Preferably, a temperature sensor is provided on the outer wall of the core, and the temperature sensor is connected to the input end of the temperature control device.

A method for evaluating the integrity of an irregular wellbore cement sheath, comprising the following steps:

According to the needs of the experiment, select the core with corresponding parameters, and select the drill bit with the corresponding size to process the core to obtain an irregular wellbore;

Put the treated rock core into the kettle body of the high-temperature and high-pressure autoclave, and put the casing in the irregular wellbore;

Inject cement slurry into the annulus between the irregular wellbore and the casing, and allow it to set;

Install the lid of the high-temperature and high-pressure kettle on the top of the kettle body to form a pressure-resistant sealed kettle;

At the beginning of the experiment, according to the maximum/minimum horizontal ground stress requirements of the experiment, the hydraulic control device controls the pressure in the hydraulic chamber to push multiple groups of pressurized plates to generate confining pressures of different sizes in multiple directions on the core, simulating the real downhole pressure environment;

After the experiment, the simulation device was taken out as a whole, and the sealing integrity of the cement sheath was evaluated.

Preferably, according to the temperature requirements of the experiment, a heating insulation cover is provided between the inner wall of the kettle and the hydraulic chamber, the heating insulation cover is connected with a temperature control device, and the temperature control device controls the heating insulation cover to heat and maintain the hydraulic chamber. The temperature is constant, simulating the real downhole temperature environment.

Preferably, after the experiment is over, the interface damage and body damage of the cement sheath are obtained by performing a CT three-dimensional scan on the whole simulation device.

Compared with the prior art, the present invention has the following beneficial effects:

The present invention provides an irregular wellbore cement sheath seal integrity evaluation device, which introduces the important factor of irregular wellbore into the cement sheath seal integrity evaluation experiment. Realizing the irregularity of the wellbore under actual working conditions, the integrity of the cement sheath seal under different lithology, wellbore quality, temperature, wellbore internal pressure change, maximum and minimum horizontal principal stress, cement performance and other conditions are simulated during the experiment , to improve the realism of the simulation. Wellbores of different qualities and shapes can be drilled in rocks of different lithologies as required; the whole rock with holes is placed in a high-temperature autoclave, and by applying confining pressure in different directions, the real working conditions of the downhole can be simulated. The influence of different maximum and minimum horizontal principal stresses, rock porosity, permeability, lithology and other formation rock properties on the integrity of the cement sheath seal is analyzed. After the experiment, the core-cement sheath-casing simulation device assembly can be taken out as a whole, and the overall evaluation can finely analyze the cement sheath interface damage and body damage, which significantly improves the accuracy of the cement sheath seal integrity evaluation, and the sealing performance Well, both simulation and analysis results are closer to real conditions.

Description of drawings

Fig. 1 is a schematic diagram of an irregular wellbore cement sheath seal integrity evaluation device of the present invention;

Fig. 2 is a schematic diagram of irregular borehole drilling of the present invention;

Fig. 3 is a top view of the section A-A of Fig. 1 of the present invention.

In the figure, rock core 1, cement sheath 2, casing 3, high temperature and high temperature autoclave cover 4, kettle body 5, hydraulic chamber 6, pressure plate 7, heating insulation jacket 8, hydraulic control device 9, temperature control device 10.

Detailed ways

The present invention will be further described in detail below in conjunction with specific embodiments, which are explanations of the present invention rather than limitations.

The present invention is an irregular wellbore cement sheath seal integrity evaluation device, including a simulation device and a control device;

The simulation device includes a rock core 1, a cement sheath 2 and a casing 3. An irregular wellbore is opened in the rock core 1, and a casing 3 is arranged in the irregular wellbore. The ring formed between the irregular wellbore and the casing 3 Inject cement slurry into the space to form a cement sheath 2;

The control device includes a high-temperature autoclave and a hydraulic control device 9, and the high-temperature autoclave includes a high-temperature autoclave cover 4 and a still body 5;

During the evaluation, the simulation device is installed in the kettle body 5 of the high-temperature autoclave, and multiple groups of pressure plates 7 are arranged on the periphery of the rock core 1, and a hydraulic chamber 6 is formed between the pressure plate 7 and the inner wall of the kettle body 5 of the high-temperature autoclave. The hydraulic chamber 6 is connected to the output end of the hydraulic control device 9 .

The present invention provides a cement sheath seal integrity evaluation device for irregular boreholes, which introduces the important factor of irregular boreholes into the cement sheath 2 seal integrity evaluation experiment, by setting irregular boreholes of different shapes in the core 1 , taking into account the irregularity of the wellbore under actual working conditions, and at the same time simulate the cement sheath under different lithology, wellbore quality, temperature, wellbore internal pressure change, maximum and minimum horizontal principal stress, cement stone properties and other conditions during the experiment. Seal integrity for increased simulation fidelity. Wellbores of different qualities and shapes can be drilled in rocks of different lithologies as required; the whole rock with holes is placed in a high-temperature autoclave, and by applying confining pressure in different directions, the real working conditions of the downhole can be simulated. The influence of different maximum and minimum horizontal principal stresses, rock porosity, permeability, lithology and other formation rock properties on the integrity of the cement sheath seal is analyzed. After the experiment, the simulation device assembly of core 1-cement sheath 2-casing 3 can be taken out as a whole, and the evaluation of the whole can finely analyze the cement sheath 2 interface damage and body damage, which significantly improves the integrity evaluation of the cement sheath seal. Accuracy, good sealing performance, while the simulation and analysis results are closer to the real working conditions.

Further, the shape and size of the irregular wellbore are determined according to the size of different drill bits and different drilling depths.

In the present invention, by changing the size of the drill bit and the drilling depth of the drill bit when drilling, it is possible to simulate the situation that the wellbore is mostly spiral or the diameter of the well under the actual working condition is changed, so that the cement sheath of the wellbore under the real working condition 2 The sealing integrity is evaluated, and the important factor of irregular wellbore is introduced into the cement sheath 2 sealing integrity evaluation experiment.

In this embodiment, four sets of pressure plates 7 are arranged on the periphery of the rock core 1 and four sets of hydraulic chambers 6 are formed correspondingly.

In this embodiment, the output ends of the hydraulic control device 9 are respectively connected to four sets of hydraulic chambers 6 and sleeves 3 for controlling the pressure inside the hydraulic chambers 6 and sleeves 3 .

In this embodiment, by setting four sets of pressure plates 7 and hydraulic chambers 6, confining pressures of different sizes in four directions are generated on the core 1, simulating the real downhole pressure environment, and the hydraulic control device 9 can control and adjust the pressure control range, generally It is 0-50MPa, and the control pressure accuracy is ±0.1Mpa, which can realize the control of the maximum/minimum horizontal stress. At the same time, the hydraulic control device 9 is also connected with the casing 3, which can control and adjust the pressure inside the casing 3, simulating The change of wellbore internal pressure further improves the authenticity of the simulation, thereby improving the evaluation accuracy.

Another preferred embodiment, the outer wall of the rock core 1 may also be provided with a pressure sensor in the circumferential direction, and the pressure sensor is connected to the input end of the hydraulic control device 9 .

In this embodiment, pressure sensors are used to monitor and measure the pressure on the core 1 and the cement sheath 2, and the measurement results are fed back to the hydraulic control device 9 in real time to assist the hydraulic control device 9 in precisely controlling pressure and simulating real working conditions.

Further, it also includes a temperature control device 10 and a heating insulation jacket 8;

The heating and insulating jacket 8 is arranged between the inner wall of the kettle body 5 and the hydraulic cavity 6 , and the heating and insulating jacket 8 is connected to the output end of the temperature control device 10 .

The present invention is also provided with a temperature control module, including a temperature control device 10 and a heating insulation jacket 8, which are used to control and adjust the experimental temperature and simulate the real downhole temperature environment.

In another preferred embodiment, a temperature sensor can also be arranged circumferentially on the outer wall of the core 1 , and the temperature sensor is connected to the input end of the temperature control device 10 .

In this embodiment, temperature sensors are used to monitor and measure the heating temperature of the core 1 and the cement sheath 2, and the measurement results are fed back to the temperature control device 10 in real time to assist the temperature control device 10 in precise temperature control and simulate real working conditions.

The present invention also provides a method for evaluating the integrity of an irregular wellbore cement sheath, comprising the following steps:

Select the core 1 with corresponding parameters according to the experimental requirements, and select a drill bit with a corresponding size to process the core 1 to obtain an irregular wellbore;

Put the treated rock core 1 into the kettle body 5 of the high-temperature autoclave, and put the casing 3 in the irregular borehole;

Inject cement slurry into the annulus between the irregular wellbore and the casing 3, and allow it to solidify;

The high-temperature autoclave cover 4 is mounted on the top of the kettle body 5 to form a pressure-resistant sealed kettle;

At the beginning of the experiment, according to the requirement of the maximum/minimum horizontal ground stress in the experiment, the hydraulic control device 9 controls the pressure in the hydraulic chamber 6 to push multiple groups of pressurized plates 7 to generate confining pressures of different sizes in multiple directions on the core 1, simulating the actual downhole pressure. stressful environment;

After the experiment, the simulation device was taken out as a whole, and the sealing integrity of the cement sheath 2 was evaluated.

Further, according to the temperature requirements of the experiment, a heating insulation cover 8 is provided between the inner wall of the kettle body 5 and the hydraulic chamber 6, the heating insulation cover 8 is connected with a temperature control device 10, and the temperature control device 10 controls the heating insulation cover 8 The hydraulic chamber 6 is heated and kept at a constant temperature, simulating the real downhole temperature environment.

In this embodiment, after the experiment is over, the interface damage and body damage of the cement sheath 2 are acquired through CT three-dimensional scanning of the whole simulation device.

Example

The present invention provides specific implementation steps of an embodiment, including:

Step 1: According to the specific needs of the experiment on rock porosity, permeability, lithology, etc., select the core 1 with corresponding parameters; use different sizes of drill bits to drill irregular boreholes on the core 1. The shape of the irregular borehole depends on the size and drilling depth of the selected drill bit. Therefore, related operations can be repeated to obtain multiple irregular boreholes with the same shape, which is convenient for multiple sets of experimental tests.

Step 2: Put the treated rock core 1 in step 1 into the high-temperature autoclave body 5, put the casing 3 in the irregular wellbore, inject cement slurry into the annular space formed by the casing 3 and the irregular wellbore, And Hou Ning.

Step 3: Install the high-temperature autoclave cover 4 on the high-temperature autoclave body 5 to form a pressure-resistant sealed kettle.

Step 4: According to the requirement of the maximum/minimum horizontal ground stress in the experiment, the hydraulic control system controls the pressure of the 4 hydraulic chambers 6, and then pushes the 4 pressure plates 7 to generate confining pressures of different sizes in 4 directions on the core 1, simulating the real Downhole pressure environment.

Step 5: According to the temperature requirements of the experiment, the temperature control system controls the heating insulation jacket 8 to heat the chamber and maintain a constant temperature, simulating the real downhole temperature environment.

Step 6: Through the hydraulic control system, the pressure changes in the hydraulic chamber 6 and the casing 3 can be adjusted to simulate real downhole stress changes and wellbore internal pressure changes.

Step 7: After the test in step 6, open the high-temperature autoclave cover 4, take out the core 1-cement sheath 2-casing 3 as a whole, and perform CT three-dimensional scanning. On the premise of not damaging the cement sheath 2 body and the cemented interface, Accurately measure the interface damage and body damage of the cement sheath 2.

In order to realize the above object, the main technical means taken in the present invention. It shall be described clearly, completely and accurately, and the essential content of the invention shall be explained, and the degree of disclosure shall be subject to the understanding and realization of those skilled in the art.

Claims (10)

1. An irregular wellbore cement sheath seal integrity evaluation device, characterized in that it includes a simulation device and a control device; The simulation device includes a rock core (1), a cement sheath (2) and a casing (3). An irregular wellbore is opened in the rock core (1), and a casing (3) is arranged in the irregular wellbore. Cement slurry is injected into the annular space formed between the eye and the casing (3) to form a cement sheath (2); The control device includes a high-temperature autoclave and a hydraulic control device (9), and the high-temperature autoclave includes a high-temperature autoclave cover (4) and a still body (5); During evaluation, the simulation device is arranged in the still body (5) of the high-temperature autoclave, and multiple groups of pressure plates (7) are arranged on the periphery of the rock core (1), and the pressure plates (7) are connected with the still body (5) of the high-temperature autoclave ( 5) A hydraulic chamber (6) is formed between the inner walls, and the hydraulic chamber (6) is connected to the output end of the hydraulic control device (9). 2. A device for evaluating the integrity of a cement sheath seal in an irregular wellbore according to claim 1, wherein the shape and size of the irregular wellbore are determined according to the size of different drill bits and different drilling depths. 3. A device for evaluating the integrity of cement sheath seals in irregular boreholes according to claim 1, characterized in that four sets of pressure plates (7) are arranged on the periphery of the rock core (1) and four sets of pressure plates (7) are formed correspondingly Hydraulic chamber (6). 4. A device for evaluating the integrity of an irregular wellbore cement sheath seal according to claim 3, wherein the output ends of the hydraulic control device (9) are respectively connected to four sets of hydraulic chambers (6) and casings (3), used to control the pressure inside the hydraulic chamber (6) and casing (3). 5. A kind of irregular wellbore cement sheath seal integrity evaluation device according to claim 1, is characterized in that, the outer wall of described rock core (1) is provided with pressure sensor, pressure sensor and hydraulic control device (9) input connection. 6. A kind of irregular wellbore cement sheath seal integrity evaluation device according to claim 1, is characterized in that, also comprises temperature control device (10) and heating insulation cover (8); The heating and insulating jacket (8) is arranged between the inner wall of the kettle body (5) and the hydraulic cavity (6), and the heating and insulating jacket (8) is connected to the output end of the temperature control device (10). 7. A kind of irregular wellbore cement sheath seal integrity evaluation device according to claim 6, is characterized in that, the outer wall of described rock core (1) is provided with temperature sensor, temperature sensor and temperature control device (10) input connection. 8. A method for evaluating the integrity of an irregular wellbore cement sheath, characterized in that, based on the evaluation device according to any one of claims 1-7, comprising the steps of: Selecting a rock core (1) with corresponding parameters according to the needs of the experiment, and selecting a drill bit of a corresponding size to process the rock core (1) to obtain an irregular borehole; Putting the treated rock core (1) into the kettle body (5) of the high-temperature autoclave, and putting the casing (3) in the irregular wellbore; Inject cement slurry into the annular space between the irregular wellbore and the casing (3), and allow it to solidify; The high-temperature autoclave cover (4) is installed on the top of the kettle body (5) to form a pressure-resistant sealed kettle; At the beginning of the experiment, according to the requirement of the experiment for the maximum/minimum horizontal stress, the hydraulic control device (9) controls the pressure in the hydraulic chamber (6) to push multiple sets of pressurized plates (7) to produce multiple directions of different sizes on the core (1). The confining pressure simulates the real downhole pressure environment; After the experiment, the simulation device was taken out as a whole, and the sealing integrity of the cement sheath (2) was evaluated. 9. A kind of irregular wellbore cement sheath seal integrity evaluation method according to claim 8, is characterized in that, also comprises according to the requirement of experiment to temperature, between kettle body (5) inner wall and hydraulic chamber (6) There is a heating insulation cover (8) between them, and the heating insulation cover (8) is connected with a temperature control device (10), and the temperature control device (10) controls the heating insulation cover (8) to heat the hydraulic chamber (6) and maintain a constant temperature , to simulate the real downhole temperature environment. 10. a kind of irregular wellbore cement sheath sealing integrity evaluation method according to claim 8, is characterized in that, after described experiment finishes, obtain the interface of cement sheath (2) by carrying out CT three-dimensional scanning to the simulation device whole Damage and body damage.

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