Method for determining plugging thickness of adjacent stratums of shale reservoir based on temperature field simulation

Abstract

The invention discloses a method for determining the plugging thickness of adjacent stratums of a shale reservoir based on temperature field simulation, which comprises the following steps: preparing a roof rock sample by using an overlying rock coring section of the shale reservoir, wrapping the roof rock sample by using a non-pressure-building heat insulation material, and arranging a heating device and a temperature sensor on the bottom surface of the roof rock sample, arranging a plurality of temperature sensors on the side surface of the roof rock sample according to set intervals; heating the roof rock sample by using a heating device until the temperature of the bottom temperature sensor is a first set temperature, stabilizing the temperature until the variation amplitude of the measured value of each temperature sensor is smaller than a set threshold value, and determining the lowest position where the temperature of the roof rock sample is not higher than a second set temperature according to the measured values of the temperature sensors; determining the lower limit of the shale reservoir roof plugging thickness according to the distance between the position and the bottom surface; and similarly, determining the lower limit of the plugging thickness of the shale reservoir bottom plate. According to the method, reasonable quantification of the lower limit of the plugging thickness of the top and bottom plates of the shale reservoir can be realized through temperature field simulation.

Description

Technical Field

[0001] The invention relates to the technical field of petroleum geology and shale reservoir exploitation, and in particular to a method for determining the sealing thickness of adjacent strata of a shale reservoir based on temperature field simulation. Background Art

[0002] my country's medium- and low-maturity oil shale has huge resource potential, and in-situ mining technology has been increasingly valued by all walks of life as an effective way to achieve its industrialized mining. In-situ mining technology is to directly heat the underground shale reservoir to cause it to crack underground, and the generated oil and gas are extracted through production wells. Whether the overlying rock layer can be effectively blocked during the in-situ mining of shale reservoirs is one of the key factors in improving the recovery rate. The existing technology does not have an effective means to evaluate the roof blocking performance during the in-situ mining of shale reservoirs. Summary of the invention

[0003] In order to at least partially solve the above-mentioned technical problems existing in the prior art, the inventors have made the present invention, and through a specific implementation method, provide a method for determining the sealing thickness of adjacent formations of a shale reservoir based on temperature field simulation, which can reasonably quantify the lower limit of the sealing thickness of the top plate of the shale reservoir through the temperature field simulation method.

[0004] An embodiment of the present invention provides a method for determining the sealing thickness of adjacent formations of a shale reservoir based on temperature field simulation, comprising:

[0005] A roof rock sample is prepared by coring a coring section of an overlying rock formation of a shale reservoir, a side of the roof rock sample is wrapped by a heat-insulating material that does not block pressure, a first heating device and a first temperature sensor are arranged on the bottom surface of the roof rock sample, and a plurality of first temperature sensors are arranged on the side of the roof rock sample at a first set interval;

[0006] The top plate rock sample is heated by the first heating device until the temperature measured by the first temperature sensor at the bottom is the first set temperature, and is stabilized at the temperature until the measured temperature variation amplitude of each first temperature sensor is less than the set threshold value, and the lowest position where the top plate rock sample temperature is not higher than the second set temperature is determined according to the measured temperature of the first temperature sensor;

[0007] The lower limit of the top plate plugging thickness of the shale reservoir is determined according to the distance from the position to the bottom surface.

[0008] In some embodiments, the first set temperature is the lowest temperature at which the kerogen conversion rate in the shale reservoir reaches a set conversion rate threshold.

[0009] In some embodiments, the first set temperature is the lowest temperature at which the kerogen conversion rate in the shale reservoir reaches 90%;

[0010] The first set temperature is 290-330°C.

[0011] In some embodiments, the second set temperature is the initial hydrocarbon production temperature of kerogen in the overlying rock formation.

[0012] In some embodiments, the second set temperature is 200-250°C.

[0013] In some embodiments, the length of the roof rock sample is not less than 500 cm.

[0014] In some embodiments, the first heating device is a one-way heating device;

[0015] The first heating device is located at the center of the bottom surface of the top plate rock sample;

[0016] The area of ​​the bottom surface of the top plate rock sample directly heated by the first heating device does not exceed 1 / 4 of the bottom surface area.

[0017] In some embodiments, the first set interval is set according to measurement accuracy requirements.

[0018] In some embodiments, it also includes:

[0019] A bottom plate rock sample is prepared by coring a coring section of an underlying rock formation of a shale reservoir, a side surface of the bottom plate rock sample is wrapped by a heat-insulating material that does not block pressure, a second heating device and a second temperature sensor are arranged on the top surface of the bottom plate rock sample, and a plurality of second temperature sensors are arranged on the side surface of the bottom plate rock sample at a second set interval;

[0020] The bottom plate rock sample is heated by the second heating device until the temperature measured by the second temperature sensor on the top is the first set temperature, and stabilized at the temperature until the measured temperature variation amplitude of each second temperature sensor is less than the set threshold value, and the highest position where the bottom plate rock sample temperature is not higher than the third set temperature is determined according to the measured temperature of the second temperature sensor;

[0021] The lower limit of the bottom plate plugging thickness of the shale reservoir is determined according to the distance between the position and the top surface.

[0022] In some embodiments, the third set temperature is the initial hydrocarbon production temperature of kerogen in the underlying rock formation.

[0023] The beneficial effects of the above technical solution provided by the embodiment of the present invention include at least:

[0024] (1) The method for determining the plugging thickness of adjacent strata of a shale reservoir based on temperature field simulation provided by an embodiment of the present invention uses a first heating device to heat the top plate rock sample so that the measured temperature of the first temperature sensor at the bottom is stabilized at the first set temperature until the measured temperature of each first temperature sensor is stable, and the lowest position where the top plate rock sample temperature is not higher than the second set temperature is determined based on the measured temperature of the first temperature sensor; the lower limit of the top plate plugging thickness of the shale reservoir is determined based on the distance between the position and the bottom surface. The lower limit of the top plate plugging thickness of the shale reservoir is determined based on the temperature field simulation by an experimental method, and the top plate plugging conditions in the process of in-situ heating exploitation of the shale reservoir are specifically quantified, which can effectively guide production and improve the economic benefits of in-situ heating exploitation of shale oil and gas.

[0025] (2) In the method for determining the sealing thickness of adjacent formations of a shale reservoir based on temperature field simulation provided in an embodiment of the present invention, during the experiment, the temperature of the bottom of the roof is kept constant at the lowest temperature at which the kerogen conversion rate in the reservoir reaches 90%. At this temperature, the reservoir almost completes the conversion to hydrocarbons and achieves maximum oil and gas production. That is, this temperature is the highest temperature at which the reservoir may be heated during the in-situ heating and exploitation of the actual shale reservoir. Therefore, the setting of this temperature ensures the safety and rationality of the lower limit of the determined roof sealing thickness.

[0026] (3) The method for determining the plugging thickness of adjacent strata of a shale reservoir based on temperature field simulation provided by an embodiment of the present invention determines the lower limit of the roof plugging thickness based on the fact that the bottom temperature of the roof is constant at the lowest temperature at which the kerogen conversion rate in the shale reservoir reaches a set conversion rate threshold, and the temperature of the roof rock sample is not higher than the lowest position at which the kerogen initial hydrocarbon production temperature in the overlying rock formation. Once the overlying rock formation begins to produce hydrocarbons, the kerogen material changes, which in turn causes changes in the rock structure, destroying the original plugging properties. Therefore, only roofs below this temperature have plugging properties. Therefore, the setting of this temperature ensures that the lower limit of the roof plugging thickness is reasonable and has strong production guidance significance.

[0027] (4) In the method for determining the sealing thickness of adjacent strata of a shale reservoir based on temperature field simulation provided by an embodiment of the present invention, the first heating device is a unidirectional heating device to save resources; the heating position is located at the center, and the direct heating area of ​​the bottom surface of the top plate rock sample does not exceed 1 / 4 of the bottom surface area, so that the heat source can be spread upward as much as possible.

[0028] (5) When studying the sealing properties of shale reservoirs, the prior art often only focuses on the sealing properties of the roof, while ignoring the sealing effect of the floor. For in-situ heating and exploitation of shale reservoirs, poor sealing performance of the floor will still lead to the loss of oil and gas, affecting the recovery rate. The method for determining the sealing thickness of adjacent strata of a shale reservoir based on temperature field simulation provided by the embodiment of the present invention not only considers the sealing properties of the roof, but also fully considers the sealing properties of the floor, thereby ensuring the reliability of the determination of the sealing performance and further providing a guarantee for the improvement of the recovery rate.

[0029] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description, claims, and drawings.

[0030] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0032] Figure 1 This is a flow chart of a method for determining the plugging thickness of adjacent formations of a shale reservoir based on temperature field simulation in Embodiment 1 of the present invention;

[0033] Figure 2 This is a flow chart of a method for determining the plugging thickness of adjacent formations of a shale reservoir based on temperature field simulation in Embodiment 2 of the present invention;

[0034] Figure 3 This is a schematic diagram of the axial cross section of the roof rock sample in Example 3 of the present invention;

[0035] Figure 4 This is a temperature field simulation diagram in Embodiment 3 of the present invention;

[0036] Figure 5 for Figure 4 Oil saturation variation diagram at the middle temperature line 200℃ and 220℃. DETAILED DESCRIPTION

[0037] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0038] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0039] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art to which the invention belongs. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0040] In the description of the present invention, it should be noted that the terms "include", "including", "have", "contain" and the like are open terms, meaning including but not limited to.

[0041] The inventor found in his work that it is difficult to effectively evaluate the roof plugging performance in the process of heating and exploitation of shale reservoirs in the prior art. After further research and development, the inventor found that the difference in heat conduction between the roof and the bottom of the shale reservoir during in-situ heating and exploitation of the shale reservoir determines the difference in plugging thickness. Therefore, the plugging thickness of the roof and the bottom can be reasonably determined through temperature field simulation experiments. The embodiment of the present invention provides a method for determining the plugging thickness of adjacent strata of a shale reservoir based on temperature field simulation, which can reasonably quantify the lower limit of the roof plugging thickness of a shale reservoir through the temperature field simulation method.

[0042] Embodiment 1

[0043] Embodiment 1 of the present invention provides a method for determining the sealing thickness of adjacent strata of a shale reservoir based on temperature field simulation, referring to Figure 1 As shown, the following steps are included:

[0044] Step S11: Prepare a roof rock sample using a coring section of the overlying rock formation of the shale reservoir, wrap the side of the roof rock sample with a non-pressure-holding insulating material, arrange a first heating device and a first temperature sensor on the bottom surface of the roof rock sample, and arrange multiple first temperature sensors on the side of the roof rock sample at a first set interval.

[0045] A coring section of the overlying strata of the shale reservoir is used to prepare a roof rock sample with the same cross-sectional area (eg, a cylindrical shape with a diameter of 5 cm).

[0046] According to empirical data, the sealing thickness of the roof (mudstone roof) during in-situ heating and exploitation of shale reservoirs is usually within three to four hundred centimeters. Therefore, the length (thickness) of the roof rock sample is set to be no less than 500 cm. If it is thicker, the experimental difficulty and cost will increase; if it is thinner, it will easily fall below the actual lower limit of the roof's sealing thickness, resulting in experimental failure (the roof sealing thickness required for in-situ heating of shale cannot be measured).

[0047] The sides of the roof rock sample are wrapped with heat-insulating material that does not contain pressure. The insulation can prevent heat from being dissipated to the surroundings during the heating process; if there is no pressure, the pressure can be released outwards.

[0048] In some embodiments, the first heating device is a unidirectional heating device to save resources.

[0049] The first heating device is located at the center of the bottom surface of the top plate rock sample. Further, the first heating device can directly heat the bottom surface of the top plate rock sample to no more than 1 / 4 of the bottom surface area, so that the heat source can be spread upward as much as possible.

[0050] Specifically, the bottom surface of the roof rock sample refers to the side of the corresponding original underground position closest to the shale reservoir.

[0051] The first temperature sensor is arranged axially on the side of the top plate rock sample, and the first set interval of the arrangement is set according to the measurement accuracy requirement, usually at an interval of 10 cm.

[0052] Step S12: Use the first heating device to heat the top plate rock sample until the measured temperature of the first temperature sensor at the bottom is the first set temperature, and stabilize it at this temperature until the measured temperature change amplitude of each first temperature sensor is less than the set threshold value, and determine the lowest position where the top plate rock sample temperature is not higher than the second set temperature based on the measured temperature of the first temperature sensor.

[0053] In some embodiments, the first set temperature is the lowest temperature at which the kerogen conversion rate in the shale reservoir reaches a set conversion rate threshold.

[0054] The first set temperature can be determined by utilizing a source rock thermal simulation experiment or a kerogen activation energy experiment.

[0055] For example, multiple samples of shale reservoirs are taken, and source rock thermal simulation experiments are carried out respectively to measure the lowest temperature at which the kerogen conversion rate reaches a set conversion rate threshold, and the minimum value of the multiple minimum temperatures measured is determined as the first set temperature.

[0056] Furthermore, the first set temperature is the lowest temperature at which the kerogen conversion rate in the shale reservoir reaches 90%, usually 290-330°C.

[0057] The kerogen conversion rate reaches 90%. At this temperature, the reservoir almost completes the conversion to hydrocarbons and achieves maximum oil and gas production. That is, this temperature is the highest temperature at which the reservoir may be heated during the in-situ heating and exploitation of the actual shale reservoir. Therefore, the setting of this temperature ensures the safety and rationality of the lower limit of the roof plugging thickness.

[0058] In some embodiments, the second set temperature is the initial hydrocarbon production temperature of kerogen in the overlying rock formation, which is typically 200-250°C.

[0059] The second set temperature can be determined by using a source rock thermal simulation experiment.

[0060] For example, multiple samples of the overlying rock formation are taken, and thermal simulation experiments of the source rock are carried out respectively to measure the initial hydrocarbon production temperature of the kerogen, and the minimum value of the measured temperatures is determined as the second set temperature.

[0061] On the basis that the temperature at the bottom of the roof is constant at the lowest temperature at which the kerogen conversion rate in the shale reservoir reaches the set conversion rate threshold, the lower limit of the roof plugging thickness is determined according to the lowest position where the roof rock sample temperature is not higher than the initial hydrocarbon production temperature of the kerogen in the overburden. Once the overburden begins to produce hydrocarbons, the kerogen material changes, which in turn causes changes in the rock structure, destroying the original plugging property. Therefore, only the roof below this temperature has plugging properties. Therefore, the setting of this temperature ensures that the lower limit of the roof plugging thickness is reasonable and has strong production guidance significance.

[0062] The first set temperature, ie, the lowest temperature T0 at which the kerogen conversion rate in the shale reservoir reaches 90%, is determined in the above manner, and the initial hydrocarbon production temperature Tx of the kerogen in the overlying rock formation is determined.

[0063] Use the first heating device (heat source) to heat slowly (not exceeding 20°C / day), with the maximum temperature of the heat source between 400 and 650°C. Adjust the heat source power to make the bottom temperature of the roof rock sample constant at T0, until the measured temperature change amplitude of each first temperature sensor is less than the set threshold, that is, after the temperature stabilizes, collect the measured temperature of each first temperature sensor. Since the temperature of the roof rock sample gradually decreases from bottom to top, the measured temperatures of the first temperature sensors can be collected from bottom to top in sequence until the currently collected temperature is Tx or not greater than Tx. Determine the lowest position where the roof rock sample temperature is not higher than the second set temperature based on the position of the corresponding first temperature sensor.

[0064] If the currently collected temperature is Tx, the position of the corresponding first temperature sensor can be directly determined as the position where the roof rock sample temperature begins to drop to Tx; if the currently collected temperature begins to be less than Tx (the first temperature less than Tx), based on the currently collected temperature and the previous collected temperature and the position of the current first temperature sensor and the position of the previous first temperature sensor, the lowest position where the roof rock sample temperature is not higher than Tx is determined by the proportional method.

[0065] Step S13: Determine the lower limit of the roof plugging thickness of the shale reservoir according to the distance between the position and the bottom surface.

[0066] The distance between the position and the bottom surface can be directly determined as the lower limit of the roof plugging thickness of the shale reservoir; other factors affecting the plugging performance can also be further considered to determine the safety correction factor (greater than 1), and the product of the safety correction factor and the determined distance is used as the lower limit of the roof plugging thickness of the shale reservoir.

[0067] The method for determining the plugging thickness of adjacent strata of a shale reservoir based on temperature field simulation provided in the first embodiment of the present invention uses a first heating device to heat the top plate rock sample so that the measured temperature of the first temperature sensor at the bottom is stabilized at the first set temperature until the measured temperature of each first temperature sensor is stabilized, and the lowest position where the top plate rock sample temperature is not higher than the second set temperature is determined according to the measured temperature of the first temperature sensor; the lower limit of the top plate plugging thickness of the shale reservoir is determined according to the distance between the position and the bottom surface. The lower limit of the top plate plugging thickness of the shale reservoir is determined based on the temperature field simulation through an experimental method, and the top plate plugging conditions in the process of in-situ heating and exploitation of shale reservoirs are specifically quantified, which can effectively guide production and improve the economic benefits of in-situ heating and exploitation of shale oil and gas.

[0068] Embodiment 2

[0069] Embodiment 2 of the present invention provides another method for determining the plugging thickness of adjacent formations of a shale reservoir based on temperature field simulation, specifically a method for determining the lower limit of the bottom plate plugging thickness of a shale reservoir. The method for determining the lower limit of the top plate plugging thickness of a shale reservoir in the above embodiment 1 is still applicable here. For details, refer to Figure 2 As shown, the following steps are included:

[0070] Step S21: Prepare a bottom plate rock sample using the coring section of the underlying rock formation of the shale reservoir, wrap the side of the bottom plate rock sample with a non-pressure-holding insulating material, arrange a second heating device and a second temperature sensor on the top surface of the bottom plate rock sample, and arrange multiple second temperature sensors on the side of the bottom plate rock sample at a second set interval.

[0071] The second temperature sensor may be the same temperature sensor as the first temperature sensor, and the "first" and "second" here are only used to distinguish whether the temperature sensor is set in the top plate rock sample or the bottom plate rock sample.

[0072] The bottom plate rock sample with the same cross-sectional area (e.g., cylindrical with a diameter of 5 cm) is prepared by coring the underlying rock formation of the shale reservoir. The length (thickness) of the bottom plate rock sample is not less than 500 cm.

[0073] The second heating device can be the same heating device as the first heating device, and the "first" and "second" here are just to distinguish whether the heating device is arranged on the bottom surface of the top plate rock sample or the top surface of the bottom plate rock sample.

[0074] The second heating device is located at the center of the top surface of the bottom plate rock sample. Further, the second heating device may directly heat the top surface of the bottom plate rock sample to no more than 1 / 4 of the top surface area, so that the heat source can be spread downward as much as possible.

[0075] Specifically, the top surface of the bottom plate rock sample refers to the side of the corresponding original underground position closest to the shale reservoir.

[0076] The second temperature sensor is arranged axially on the side of the bottom plate rock sample. The second set interval is set according to the measurement accuracy requirement and can be consistent with the first set interval, usually 10 cm.

[0077] Step S22: Use the second heating device to heat the bottom plate rock sample until the measured temperature of the second temperature sensor on the top is the first set temperature, and stabilize it at this temperature until the measured temperature change amplitude of each second temperature sensor is less than the set threshold value, and determine the highest position where the bottom plate rock sample temperature is not higher than the third set temperature based on the measured temperature of the second temperature sensor.

[0078] In some embodiments, the third set temperature is the initial hydrocarbon production temperature of kerogen in the underlying rock formation, and its determination method can refer to the determination of the second set temperature.

[0079] This application is based on the premise that the overlying and underlying rock formations of the shale reservoir are both mudstone formations. Therefore, if the rock properties of the overlying and underlying rock formations are basically the same, the initial hydrocarbon production temperature of kerogen in the overlying rock formation can also be approximated as the initial hydrocarbon production temperature of kerogen in the underlying rock formation.

[0080] Use the second heating device (heat source) to heat slowly (not exceeding 20°C / day), with the maximum temperature of the heat source between 400 and 650°C. Adjust the heat source power to make the top temperature of the bottom plate rock sample constant T0, until the measured temperature change amplitude of each second temperature sensor is less than the set threshold, that is, after the temperature stabilizes, collect the measured temperature of each second temperature sensor. Since the temperature of the bottom plate rock sample gradually decreases from top to bottom, the measured temperatures of the second temperature sensors can be collected from top to bottom in sequence until the currently collected temperature is the third set temperature or starts to be less than the third set temperature. Determine the highest position where the bottom plate rock sample temperature is not higher than the third set temperature based on the position of the corresponding second temperature sensor.

[0081] Taking the third set temperature as Tx as an example, if the currently collected temperature is Tx, the position of the corresponding second temperature sensor can be directly determined as the position where the bottom plate rock sample temperature begins to drop to Tx; if the currently collected temperature begins to be less than Tx (the first temperature less than Tx), based on the currently collected temperature and the previous collected temperature and the current position of the second temperature sensor and the position of the previous second temperature sensor, the highest position where the bottom plate rock sample temperature is not higher than Tx is determined by the proportional method.

[0082] Step S23: Determine the lower limit of the bottom plate plugging thickness of the shale reservoir according to the distance from the position to the top surface.

[0083] The distance from this position to the top surface can be directly determined as the lower limit of the bottom plate plugging thickness of the shale reservoir; other factors affecting the plugging performance can also be further considered to determine the safety correction factor (greater than 1), and the product of the safety correction factor and the determined distance is used as the lower limit of the bottom plate plugging thickness of the shale reservoir.

[0084] When studying the sealing properties of shale reservoirs, the prior art often only focuses on the sealing properties of the top plate, while ignoring the sealing effect of the bottom plate. For in-situ heating and exploitation of shale reservoirs, poor bottom plate sealing performance will still lead to the loss of oil and gas, affecting the recovery rate. The method for determining the sealing thickness of adjacent strata of a shale reservoir based on temperature field simulation provided in the second embodiment of the present invention fully considers the sealing properties of the bottom plate, ensures the reliability of the determination of the sealing performance, and further provides a guarantee for the improvement of the recovery rate.

[0085] The above-mentioned embodiment 1 and embodiment 2 can be applied separately; or they can be applied in combination to determine both the lower limit of the top plate plugging thickness of the shale reservoir and the lower limit of the bottom plate plugging thickness of the shale reservoir. The top and bottom plate thicknesses of the shale reservoir both meet the corresponding lower limits of the plugging thickness, and then it is determined that the plugging requirements are met.

[0086] Embodiment 3

[0087] Embodiment 3 of the present invention provides a specific application of a method for determining a lower limit of the top plate plugging thickness of a shale reservoir, and verifies its accuracy through numerical simulation, including the following steps:

[0088] 1) The T0 (kerogen 90% conversion temperature) of the shale reservoir rock sample was measured to be 300°C.

[0089] 2) The Tx (initial hydrocarbon production temperature of kerogen) of the roof rock sample was measured to be 200℃.

[0090] 3) Prepare a cylindrical roof rock sample with a diameter of 5 cm and a length of 500 cm. Figure 3 The figure shows a schematic cross-sectional view of the roof rock sample along the axial direction.

[0091] 4) Wrap the roof rock sample with rock wool as the insulation material, which is not pressure-blocking, and put the wrapped roof rock sample into the experimental device. Place a unidirectional heat source point at the bottom of the roof rock sample, arrange temperature sensors from the bottom, and arrange several temperature sensors along the axial direction of the roof rock sample at intervals of 10 cm.

[0092] 5) The heat source is heated at a rate of 20°C / day, and the peak temperature is set to 300°C (T0).

[0093] 6) After the bottom of the roof rock sample is kept at a constant temperature of T0 for 30 minutes (the temperature measured by each temperature sensor reaches stability), continuously collect the roof rock sample temperature sensor data, and measure and calculate that the distance from the position of temperature Tx to the bottom of the roof rock sample is 100 cm, which is the lower limit of the roof plugging thickness.

[0094] 7) Establish a numerical model consistent with the roof rock sample and experimental conditions, and set the activation energy parameters in the chemical reaction so that the Tx (initial hydrocarbon production temperature of kerogen) of the roof rock sample is 200°C.

[0095] 8) Keep the temperature at the bottom of the top rock sample constant at T0 (300°C), complete the numerical simulation of the temperature field, and wait for the grid temperature to stabilize.

[0096] 9) See Figure 4 The figure shows the simulated temperature field of the roof rock sample. Figure 4 Oil saturation at the Tx temperature line (200°C) (see Figure 5 There was no change in the whole simulation period, indicating that oil and gas were blocked at this location.

[0097] 10) Observation Figure 4 Oil saturation at 220°C (see Figure 5 During the whole simulation period, there are obvious changes, indicating that the oil and gas are not blocked at this location.

[0098] 11) The thickness of the Tx temperature line is 105 cm. The comparison proves that the top plate with a thickness of 105 cm meets the plugging requirements. The error between the numerical simulation results and the experimental results (100 cm) is 5%, so the numerical simulation verifies the reliability of the experimental results.

[0099] It should be understood that the specific order or hierarchy of steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process can be rearranged without departing from the scope of protection of the present disclosure. The attached method claims present the elements of the various steps in an exemplary order and are not intended to be limited to the specific order or hierarchy described.

[0100] In the above detailed description, various features are grouped together in a single embodiment to simplify the disclosure. This method of disclosure should not be interpreted as reflecting an intention that the embodiments of the claimed subject matter require more features than are clearly stated in each claim. On the contrary, as reflected in the appended claims, the invention is in a state of having less than all the features of the disclosed individual embodiments. Therefore, the appended claims are hereby expressly incorporated into the detailed description, with each claim standing on its own as a separate preferred embodiment of the invention.

[0101] The above description includes examples of one or more embodiments. Of course, it is impossible to describe all possible combinations of components or methods for the purpose of describing the above embodiments, but it should be recognized by those skilled in the art that the various embodiments can be further combined and arranged. Therefore, the embodiments described herein are intended to cover all such changes, modifications and variations that fall within the scope of protection of the appended claims. In addition, with respect to the term "comprising" used in the specification or claims, the word is covered in a manner similar to the term "including", just as "including," explained as a transitional word in the claims. In addition, any term "or" used in the specification of the claims is intended to represent "non-exclusive or". The terms "first" and "second" are used for descriptive purposes and are not to be understood as indicating or implying relative importance.

Claims

1. A method for determining the sealing thickness of adjacent strata of a shale reservoir based on temperature field simulation, characterized in that: include: A roof rock sample is prepared by coring a coring section of an overlying rock formation of a shale reservoir, a side of the roof rock sample is wrapped by a heat-insulating material that does not block pressure, a first heating device and a first temperature sensor are arranged on the bottom surface of the roof rock sample, and a plurality of first temperature sensors are arranged on the side of the roof rock sample at a first set interval; The top plate rock sample is heated by the first heating device until the temperature measured by the first temperature sensor at the bottom is the first set temperature, and is stabilized at the temperature until the measured temperature variation amplitude of each first temperature sensor is less than the set threshold value, and the lowest position where the top plate rock sample temperature is not higher than the second set temperature is determined according to the measured temperature of the first temperature sensor; The lower limit of the top plate plugging thickness of the shale reservoir is determined according to the distance from the position to the bottom surface.

2. The method according to claim 1, characterized in that The first set temperature is the lowest temperature at which the kerogen conversion rate in the shale reservoir reaches a set conversion rate threshold.

3. The method according to claim 2, characterized in that The first set temperature is the lowest temperature at which the kerogen conversion rate in the shale reservoir reaches 90%; The first set temperature is 290-330°C.

4. The method according to claim 2, characterized in that The second set temperature is the initial hydrocarbon production temperature of kerogen in the overlying rock formation.

5. The method according to claim 4, characterized in that The second set temperature is 200-250°C.

6. The method according to claim 1, characterized in that The length of the roof rock sample is not less than 500 cm.

7. The method according to claim 1, characterized in that The first heating device is a one-way heating device; The first heating device is located at the center of the bottom surface of the top plate rock sample; The area of ​​the bottom surface of the top plate rock sample directly heated by the first heating device does not exceed 1 / 4 of the bottom surface area.

8. The method according to claim 1, characterized in that The first set interval is set according to the measurement accuracy requirement.

9. The method according to claim 1, characterized in that Also includes: A bottom plate rock sample is prepared by coring a coring section of an underlying rock formation of a shale reservoir, a side surface of the bottom plate rock sample is wrapped by a heat-insulating material that does not block pressure, a second heating device and a second temperature sensor are arranged on the top surface of the bottom plate rock sample, and a plurality of second temperature sensors are arranged on the side surface of the bottom plate rock sample at a second set interval; The bottom plate rock sample is heated by the second heating device until the temperature measured by the second temperature sensor on the top is the first set temperature, and stabilized at the temperature until the measured temperature variation amplitude of each second temperature sensor is less than the set threshold value, and the highest position where the bottom plate rock sample temperature is not higher than the third set temperature is determined according to the measured temperature of the second temperature sensor; The lower limit of the bottom plate plugging thickness of the shale reservoir is determined according to the distance between the position and the top surface.

10. The method according to claim 9, characterized in that The third set temperature is the initial hydrocarbon production temperature of kerogen in the underlying rock formation.

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