Method and device for determining soaking time of coal-bed gas well

Abstract

The invention provides a method and a device for determining soaking time of a coal-bed gas well, and relates to the technical field of coal-bed gas exploitation, and the method comprises the following steps: determining first coal sample information corresponding to a plurality of coal sample cores in a coal well, the first coal sample information comprises a first change rate of an adsorbed gas semaphore corresponding to a coal sample core and a second change rate of a free gas semaphore; determining a first duration according to the plurality of first change rates and the plurality of second change rates; determining a second duration corresponding to the long core after the plurality of coal sample cores are combined, the second duration being a duration when the right pressure of the long core is stable when gas and liquid are injected into the left side of the long core; and according to the first duration and the second duration, determining a soaking duration range corresponding to the coal well. And the soaking time can be accurately determined.

Description

Technical Field

[0001] This application relates to the field of coalbed methane extraction technology, and in particular to a method and apparatus for determining the well shut-in time of coalbed methane wells. Background Technology

[0002] In coalbed methane well development, hydraulic fracturing is a core technology for improving single-well productivity. After fracturing, a well-shutting process is required to allow the fracturing fluid to fully penetrate the nano- or micro-pores of the coal seam. Through competitive adsorption and replacement, adsorbed methane is converted into free methane, while simultaneously expanding the pressure wave range of the fracture and maintaining its conductivity. The proper determination of the well-shutting time directly affects the fracturing fluid replacement efficiency, fracture stability, and ultimate recovery rate.

[0003] Currently, the stagnation time is mainly determined by analyzing permeation efficiency, fracture propagation patterns, or pressure changes using molecular dynamics, fluid-structure interaction simulations, or dynamic production models. However, these methods may lead to inaccurate determinations of stagnation time due to the unique characteristics of coalbed methane reservoirs (such as the strong adsorption properties of coal and rock, complex pore structures, and differences in pressure transmission patterns compared to shale / tight reservoirs). Summary of the Invention

[0004] This application provides a method and apparatus for determining the well simmering time of coalbed methane wells, which can be used to accurately determine the well simmering time.

[0005] Firstly, this application provides a method for determining the shut-in time of a coalbed methane well, the method comprising:

[0006] Determine the first coal sample information corresponding to multiple coal sample cores in the coal mine. The first coal sample information includes the first rate of change of the adsorbed gas signal quantity and the second rate of change of the free gas signal quantity corresponding to the coal sample core.

[0007] The first duration is determined based on multiple first rates of change and multiple second rates of change;

[0008] The second time interval corresponding to the long core after combining multiple coal sample cores was determined. The second time interval is the duration during which the pressure on the right side of the long core is stable when gas and liquid are injected on the left side of the long core.

[0009] Based on the first and second durations, determine the range of time for the corresponding well-clogging.

[0010] In one possible implementation, determining the first duration based on a plurality of first rates of change and a plurality of second rates of change includes:

[0011] Determine multiple third durations where both the first and second rates of change are less than or equal to a first threshold;

[0012] The maximum value among multiple third durations is determined as the first duration.

[0013] In one possible implementation, determining the information of a first coal sample corresponding to multiple coal core samples in a coal mine includes:

[0014] Gas was injected into multiple coal core samples until the gas adsorption of the multiple coal core samples was saturated.

[0015] Liquid was injected into multiple coal core samples, and a first relationship curve was determined. The first relationship curve is used to indicate the relationship between the signal intensity of gas adsorption or ionization and a preset decay time.

[0016] Based on the first relationship curve, the adsorbed gas signal quantity and free gas signal quantity corresponding to multiple coal sample cores in the coal mine were determined;

[0017] Based on the adsorbed gas signal quantity and the free gas signal quantity, the first coal sample information corresponding to multiple coal sample cores is determined.

[0018] In one possible implementation, determining the second duration corresponding to the long core after combining multiple coal sample cores includes:

[0019] Gas was injected into the left side of the long core until the pressure on the right side of the long core stabilized;

[0020] Liquid was injected into the left side of the long core until the pressure on the right side of the long core stabilized, and the duration of liquid injection into the left side of the long core was defined as the second duration.

[0021] In one possible implementation, the method further includes:

[0022] Vacuum drying was performed on multiple coal core samples.

[0023] Determine the permeability of multiple coal sample cores after vacuum drying treatment;

[0024] Based on permeability, multiple coal core samples were combined to obtain a long core.

[0025] In one possible implementation, the time range for simmering the coal well is determined based on a first time duration and a second time duration, including:

[0026] Determine the first permeability corresponding to the long core sample; the first permeability is the average permeability corresponding to multiple coal sample core samples.

[0027] Based on the first permeability and the second duration, the upper limit of the well-sealing duration range is determined;

[0028] The duration range is determined based on the first duration and the upper limit of the duration range.

[0029] In one possible implementation, the upper limit of the well-sealing time range is determined based on a first permeability and a second duration, including:

[0030] Based on the chart and the first permeability, the fracture density corresponding to the long core is determined. The chart is used to indicate the relationship between the first permeability and the fracture density.

[0031] Determine the fracture spacing corresponding to the long core based on the fracture density;

[0032] Obtain the length of the long core sample;

[0033] The upper limit of the well-clogging time range is determined based on the fracture spacing, the second duration, and the length of the long core.

[0034] Secondly, this application provides a device for determining the stagnation time of a coalbed methane well, comprising: a first determining module, a second determining module, a third determining module, and a fourth determining module, wherein:

[0035] The first determining module is used to determine the first coal sample information corresponding to multiple coal sample cores in the coal mine. The first coal sample information includes the first rate of change of the adsorbed gas signal quantity and the second rate of change of the free gas signal quantity corresponding to the coal sample core.

[0036] The second determining module is used to determine the first duration based on multiple first rates of change and multiple second rates of change;

[0037] The third determining module is used to determine the second duration corresponding to the long core after combining multiple coal sample cores. The second duration is the duration during which the pressure on the right side of the long core remains stable when gas and liquid are injected into the left side.

[0038] The fourth determining module is used to determine the duration range of the well simmering corresponding to the coal well based on the first duration and the second duration.

[0039] In one possible implementation, the second determining module is specifically used for:

[0040] Determine multiple third durations where both the first and second rates of change are less than or equal to a first threshold;

[0041] The maximum value among multiple third durations is determined as the first duration.

[0042] In one possible implementation, the first determining module is specifically used for:

[0043] Gas was injected into multiple coal core samples until the gas adsorption of the multiple coal core samples was saturated.

[0044] Liquid was injected into multiple coal core samples, and a first relationship curve was determined. The first relationship curve is used to indicate the relationship between the signal intensity of gas adsorption or ionization and a preset decay time.

[0045] Based on the first relationship curve, the adsorbed gas signal quantity and free gas signal quantity corresponding to multiple coal sample cores in the coal mine were determined;

[0046] Based on the adsorbed gas signal quantity and the free gas signal quantity, the first coal sample information corresponding to multiple coal sample cores is determined.

[0047] In one possible implementation, the third determining module is specifically used for:

[0048] Gas was injected into the left side of the long core until the pressure on the right side of the long core stabilized;

[0049] Liquid was injected into the left side of the long core until the pressure on the right side of the long core stabilized, and the duration of liquid injection into the left side of the long core was defined as the second duration.

[0050] In one possible implementation, the coalbed methane well shut-in time determination device further includes a processing module, which is used for:

[0051] Vacuum drying was performed on multiple coal core samples.

[0052] Determine the permeability of multiple coal sample cores after vacuum drying treatment;

[0053] Based on permeability, multiple coal core samples were combined to obtain a long core.

[0054] In one possible implementation, the fourth determining module is specifically used for:

[0055] Determine the first permeability corresponding to the long core sample; the first permeability is the average permeability corresponding to multiple coal sample core samples.

[0056] Based on the first permeability and the second duration, the upper limit of the well-sealing duration range is determined;

[0057] The duration range is determined based on the first duration and the upper limit of the duration range.

[0058] In one possible implementation, the fourth determining module is specifically used for:

[0059] Based on the chart and the first permeability, the fracture density corresponding to the long core is determined. The chart is used to indicate the relationship between the first permeability and the fracture density.

[0060] Determine the fracture spacing corresponding to the long core based on the fracture density;

[0061] Obtain the length of the long core sample;

[0062] The upper limit of the well-clogging time range is determined based on the fracture spacing, the second duration, and the length of the long core.

[0063] Thirdly, embodiments of this application provide an electronic device, including: at least one processor and a memory; the memory stores computer-executable instructions; at least one processor executes the computer-executable instructions stored in the memory, causing at least one processor to execute the method for determining the well simmering time of a coalbed methane well as described in the first aspect above and any of the first aspects.

[0064] Fourthly, embodiments of this application provide a computer-readable storage medium storing computer-executable instructions. When a processor executes the computer-executable instructions, it implements the method for determining the well simmering time of a coalbed methane well as described in the first aspect above and any of the first aspects.

[0065] This application provides a method and apparatus for determining the shut-in time of coalbed methane wells. The method determines a first duration by acquiring the rate of change of adsorbed and free gas signals in coal sample cores. Simultaneously, it determines a second duration by combining the pressure stabilization time on the right side of the coal sample core after gas and fluid injection. Finally, the shut-in time range is determined based on the first and second durations. This method takes into account the two core characteristics of coalbed methane reservoirs: coal adsorption characteristics and reservoir pressure transmission patterns. It accurately matches the dynamic process of gas desorption and replacement while ensuring the stability of fracture pressure wave range and conductivity. This allows for precise determination of the shut-in time, improving fracturing fluid replacement efficiency and the final recovery rate of coalbed methane wells, thereby enhancing development benefits. Attached Figure Description

[0066] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0067] Figure 1 A flowchart illustrating a method for determining the simmering time of a coalbed methane well, provided as an embodiment of this application;

[0068] Figure 2 A schematic diagram of pressure change provided for an embodiment of this application;

[0069] Figure 3 A flowchart illustrating a method for determining information of a first coal sample provided in an embodiment of this application;

[0070] Figure 4 A schematic diagram of a first relationship curve provided for an embodiment of this application;

[0071] Figure 5 A flowchart illustrating a method for determining a duration range provided in an embodiment of this application;

[0072] Figure 6 A schematic diagram of a drawing provided for an embodiment of this application;

[0073] Figure 7A schematic diagram of a device for determining the simmering time of a coalbed methane well, provided in an embodiment of this application;

[0074] Figure 8 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application.

[0075] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0076] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0077] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in one or more embodiments of this specification are all information and data authorized by the user or fully authorized by all parties. Furthermore, the collection, use and processing of related data must comply with relevant laws, regulations and standards, and corresponding operation entry points are provided for users to choose to authorize or refuse.

[0078] It should be noted that in the embodiments of this application, certain software, components, models and other existing solutions in the industry may be mentioned. These should be regarded as exemplary and are only intended to illustrate the feasibility of implementing the technical solution of this application. However, it does not mean that the applicant has used or necessarily used the solution.

[0079] In coalbed methane well development, hydraulic fracturing is a core technology for improving single-well productivity. After fracturing, a well-shutting process is required to allow the fracturing fluid to fully penetrate the nano- or micro-pores of the coal seam. Through competitive adsorption and replacement, adsorbed methane is converted into free methane, while simultaneously expanding the pressure wave range of the fracture and maintaining its conductivity. The appropriate well-shutting time directly affects the fracturing fluid replacement efficiency, fracture stability, and ultimate recovery rate. If the well-shutting time is too short, the fracturing fluid fails to fully absorb and replace the adsorbed methane, and the fracture closes prematurely during the flowback stage, leading to a decrease in conductivity and severely impacting development efficiency. Conversely, if the well-shutting time is too long, it may waste production time and increase costs.

[0080] Currently, the stagnation time is mainly determined by analyzing permeation efficiency, fracture propagation patterns, or pressure changes using molecular dynamics, fluid-structure interaction simulations, or dynamic production models. However, these methods may lead to inaccurate determinations of stagnation time due to the unique characteristics of coalbed methane reservoirs (such as the strong adsorption properties of coal and rock, complex pore structures, and differences in pressure transmission patterns compared to shale / tight reservoirs).

[0081] To address the aforementioned issues, this application provides a method for determining the shut-in time of a coalbed methane well. This method involves determining first coal sample information corresponding to multiple coal core samples in the well. The first coal sample information includes a first rate of change of the adsorbed gas signal quantity and a second rate of change of the free gas signal quantity corresponding to the coal core sample. Based on the multiple first and second rates of change, a first duration is determined. A second duration is determined corresponding to a long core sample formed by combining multiple coal core samples. The second duration is the duration during which the pressure on the right side of the long core sample remains stable when gas and liquid are injected into the left side of the long core sample. Based on the first and second durations, the range of shut-in time corresponding to the coal well is determined.

[0082] In the above method, the first duration is determined by obtaining the rate of change of the adsorbed and free gas signals in the coal sample core. At the same time, the second duration is determined by combining the pressure stabilization time on the right side after gas and fluid injection in the coal sample core. Finally, the well-closing time range is determined based on the first and second durations. This method takes into account the two core special characteristics of coalbed methane reservoirs: coal adsorption characteristics and reservoir pressure transmission law. It accurately matches the dynamic process of gas desorption and replacement while ensuring the stability of the fracture pressure wave range and conductivity. This method can achieve accurate determination of well-closing time, improve fracturing fluid replacement efficiency and the final recovery rate of coalbed methane wells, and improve development benefits.

[0083] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0084] Figure 1 This is a flowchart illustrating a method for determining the shut-in time of a coalbed methane well, provided as an embodiment of this application. Please refer to... Figure 1 As shown, the method may include the following steps:

[0085] S101. Determine the first coal sample information corresponding to multiple coal sample cores in the coal mine. The first coal sample information includes the first rate of change of the adsorbed gas signal quantity and the second rate of change of the free gas signal quantity corresponding to the coal sample core.

[0086] The execution subject of this application embodiment can be an electronic device or a coalbed methane well simmering time determination device installed in an electronic device. The coalbed methane well simmering time determination device can be implemented by software or by a combination of software and hardware.

[0087] In one possible implementation, a coal core refers to a columnar coal sample obtained from the reservoir section of a target coalbed methane well, which retains the original coal seam structure and physical properties. The shape of the coal core can be a plunger or similar.

[0088] In one possible implementation, the adsorbed gas signal quantity refers to the characteristic signal intensity value generated by the gas adsorbed in the pores on the surface of the coal sample core through intermolecular forces and detected by a nuclear magnetic resonance spectrometer or gas chromatograph. The signal quantity is positively correlated with the content of the adsorbed gas.

[0089] In one possible implementation, the free gas signal quantity refers to the characteristic signal intensity value generated by the gas in the pores of the coal sample core under the detection instrument, and the signal quantity is positively correlated with the molar volume of the free gas.

[0090] For example, the gas is methane, etc.

[0091] S102. Determine the first duration based on multiple first rates of change and multiple second rates of change.

[0092] In one possible implementation, each coal sample core corresponds to a first rate of change and a second rate of change, and multiple coal sample cores correspond to multiple first rates of change and multiple second rates of change.

[0093] In some implementations, multiple third durations can be determined where both the first and second rates of change are less than or equal to a first threshold; the maximum value among the multiple third durations is determined as the first duration.

[0094] The first threshold can be preset, for example, 3%.

[0095] S103. Determine the second duration corresponding to the long core after combining multiple coal sample cores. The second duration is the duration during which the pressure on the right side of the long core is stable when gas and liquid are injected on the left side of the long core.

[0096] In some implementations, multiple coal sample cores obtained after executing S102 can be vacuum dried; the permeability of the multiple coal sample cores after vacuum drying can be determined; based on the permeability, the multiple coal sample cores can be combined to obtain a long core.

[0097] In one possible implementation, determining the permeability of multiple coal core samples after vacuum drying may include: placing the vacuum-dried coal core samples in a permeameter, setting the experimental temperature to the formation temperature, setting the confining pressure to the overlying formation stress, and measuring the permeability of each coal core sample. The unit of permeability may be darcy (D) or millidarcy (mD), etc., and this application does not limit this.

[0098] In one possible implementation, based on permeability, multiple coal core samples are combined to obtain a long core, which may include:

[0099] Based on the permeability, coal core samples can be sorted and multiple coal core samples can be combined into long cores according to the order of decreasing permeability from left to right.

[0100] For example, the permeability of multiple coal sample cores from the combined long core is shown in Table 1.

[0101] Table 1

[0102]

[0103] For example, coal core number 1 can be placed at the far left, coal core number 2 at the second left, coal core number 9 at the second right, coal core number 10 at the far right, and so on.

[0104] In some implementations, the second duration corresponding to a long core obtained by combining multiple coal sample cores is determined, including:

[0105] Gas was injected into the left side of the long core until the pressure on the right side of the long core stabilized; liquid was injected into the left side of the long core until the pressure on the right side of the long core stabilized, and the duration of liquid injection on the left side of the long core was determined as the second duration.

[0106] Among them, the stability of the right-side pressure of the long core means that the change in the right-side pressure of the long core within a preset pressure monitoring interval (e.g., 12 hours) is less than or equal to the preset pressure threshold (e.g., 0.01 megapascal, MPa).

[0107] For example, the liquid is a liquid phase, heavy water, or fracturing fluid.

[0108] In one possible implementation, injecting gas into the left side of the long core until the pressure on the right side of the long core stabilizes can include:

[0109] Place the long core in the long core holder, set the temperature to the formation temperature, set the confining pressure to the overlying formation stress, and set the methane injection pressure to the formation pressure. Inject gas into the long core from the left side, and monitor the pressure value at the right outlet end of the long core during the injection process until the pressure on the right side of the long core stabilizes.

[0110] In one possible implementation, injecting fluid into the left side of the long core until the pressure on the right side of the core stabilizes can include:

[0111] Set the liquid injection pressure to the same value as the bottom hole pressure after fracturing and pump shutdown (e.g., 25 MPa), and inject the liquid from the left side of the long core into the long core. During the injection process, monitor the pressure value at the right outlet end of the long core until the pressure on the right side of the long core stabilizes.

[0112] For example, Figure 2 This is a schematic diagram of a pressure change provided in an embodiment of this application. It should be noted that... Figure 2 Taking the stability of the right-side pressure of a long core as an example, where the change in right-side pressure within 12 hours is less than or equal to 0.01 MPa, the following explanation is provided: Figure 2 As shown, the horizontal axis represents the duration of liquid injection on the left side of the long core, and the vertical axis represents the pressure value on the right side of the long core. When the duration of liquid injection on the left side of the long core is about 180 hours, the pressure at the outlet end on the right side of the long core changes by less than 0.01 MPa at 12-hour intervals. Therefore, the second duration is 180 hours.

[0113] S104. Determine the range of the simmering time for the coal well based on the first and second durations.

[0114] In one possible implementation, after determining the range of simmering time for the corresponding coal mine, on-site construction personnel can flexibly select the specific simmering time within that range based on the actual construction schedule.

[0115] It should be noted that the range of well stagnation time determined by the above method is not only applicable to the target coal well (the coal well mentioned in the above embodiment), but can also be extended to other coalbed methane wells that belong to the same block as the target coal well and have similar reservoir geological conditions and fracturing construction parameters, so as to achieve efficient and unified planning of well stagnation time within the block.

[0116] In this embodiment of the application, first coal sample information corresponding to multiple coal sample cores in a coal mine is determined. The first coal sample information includes a first rate of change of adsorbed gas signal quantity and a second rate of change of free gas signal quantity corresponding to the coal sample core. A first duration is determined based on multiple first rates of change and multiple second rates of change. A second duration corresponding to a long core after combining multiple coal sample cores is determined. The second duration is the duration during which the pressure on the right side of the long core is stable when gas and liquid are injected on the left side of the long core. The duration range of well shut-in corresponding to the coal mine is determined based on the first duration and the second duration.

[0117] In the above method, the first duration is determined by obtaining the rate of change of the adsorbed and free gas signals in the coal sample core. At the same time, the second duration is determined by combining the pressure stabilization time on the right side after gas and fluid injection in the coal sample core. Finally, the well-closing time range is determined based on the first and second durations. This method takes into account the two core special characteristics of coalbed methane reservoirs: coal adsorption characteristics and reservoir pressure transmission law. It accurately matches the dynamic process of gas desorption and replacement while ensuring the stability of the fracture pressure wave range and conductivity. This method can achieve accurate determination of well-closing time, improve fracturing fluid replacement efficiency and the final recovery rate of coalbed methane wells, and improve development benefits.

[0118] Based on any of the above embodiments, the following, in conjunction with Figure 3 A method for determining the first coal sample information corresponding to multiple coal core samples in a coal mine ( Figure 1 The S101 example will be described in detail.

[0119] Figure 3 A flowchart illustrating a method for determining information from a first coal sample, as provided in this application embodiment, is available for detailed reference. Figure 3 The method may include:

[0120] S301. Inject gas into multiple coal core samples until the gas adsorption of multiple coal core samples is saturated.

[0121] In one possible implementation, before injecting gas into multiple coal core samples, the coal core samples can be placed in a vacuum drying oven and dried under reservoir temperature conditions. Samples are taken out and weighed at preset sampling intervals until the mass change between two consecutive weighings does not exceed a preset mass threshold. For example, the preset sampling interval is 1 hour, and the preset mass threshold is 0.01 grams (g).

[0122] In one possible implementation, injecting gas into the coal sample core may include:

[0123] After vacuum drying, the coal sample core is placed in a non-magnetic holder, which is then placed in a nuclear magnetic resonance spectrometer. Fluorinated oil is used to apply confining pressure to the coal sample core. Once the change in confining pressure is less than the preset confining pressure threshold (e.g., 0.01 MPa), the gas injection pressure (e.g., 10 MPa) is determined based on the original formation pressure of the coal seam, and gas is injected into the coal sample core. During the injection process, the pressure at both ends of the coal sample core is monitored until the pressure difference at both ends of the coal sample core stabilizes.

[0124] Among them, the confining pressure can be the same as the actual overburden stress of the strata (e.g., 40 MPa). Stable pressure difference between the two ends of the coal sample core means that the change in pressure difference between the two ends of the coal sample core is less than the preset pressure difference threshold (e.g., 0.01 MPa) within a preset pressure change interval (e.g., 12 hours).

[0125] S302. Inject liquid into multiple coal sample cores and determine the first relationship curve. The first relationship curve is used to indicate the relationship between the signal intensity of gas adsorption or ionization and the preset decay time.

[0126] In one possible implementation, injecting liquid into the coal sample core may include:

[0127] The pressure of the injected liquid is set to be the same as the bottom hole pressure after the fracturing pump is stopped (e.g., 25 MPa), and the liquid is injected into the coal sample core at this pressure.

[0128] In one possible implementation, determining the first relationship curve may include:

[0129] During the injection of liquid into the coal sample core, the non-magnetic holder is scanned using an NMR spectrometer every preset scan duration (e.g., 15 minutes) to determine the first relationship curve. In the first relationship curve, the signal intensity of gas adsorption or ionization can be understood as the signal quantity (scanned by the NMR spectrometer). The preset decay time is used to indicate the pore structure characteristics. For example, in nanopores, the decay time can be set to a smaller value.

[0130] S303. Based on the first relationship curve, determine the adsorbed gas signal quantity and free gas signal quantity corresponding to multiple coal sample cores in the coal mine.

[0131] In one possible implementation, the adsorbed gas signal quantity is the area of ​​the leftmost peak curve of the first relationship curve and the horizontal axis envelope; the free gas signal quantity is the difference between the area of ​​the first relationship curve and the horizontal axis envelope and the area of ​​the leftmost peak curve of the first relationship curve and the horizontal axis envelope.

[0132] For example, Figure 4 For a schematic diagram of a first relationship curve provided in an embodiment of this application, please refer to [link / reference]. Figure 4As shown, the vertical axis of the first relationship curve represents the signal quantity, and the horizontal axis represents the decay time. Figure 4 The relationship between decay time and signal quantity is shown under different well-closing times. Figure 4 The relationship between decay time and signal quantity under adsorption equilibrium conditions is also shown. Adsorption equilibrium refers to the state in which the coal sample core and the gas reach a dynamic equilibrium of adsorption and desorption, that is, the amount of gas adsorbed on the pore surface of the coal sample core is equal to the amount of gas desorbed from the pore surface. At this time, the content of adsorbed gas in the coal sample core no longer changes with time.

[0133] based on Figure 4 The calculated data of adsorbed gas signal quantity and free gas signal quantity for different well simmering times are shown in Table 2.

[0134] Table 2

[0135]

[0136] S304. Based on the adsorbed gas signal quantity and the free gas signal quantity, determine the first coal sample information corresponding to multiple coal sample cores.

[0137] In one possible implementation, determining the first coal sample information corresponding to the coal core sample may include:

[0138] Based on the adsorbed gas signal quantity obtained at the current moment and the adsorbed gas signal quantity obtained at the previous moment, a first rate of change is determined; based on the free gas signal quantity obtained at the current moment and the free gas signal quantity obtained at the previous moment, a second rate of change is determined; based on the first rate of change and the second rate of change, the first coal sample information corresponding to the coal sample core is determined.

[0139] For example, the first rate of change can be expressed as: DX i = (X i -X i-1 ) / X i , where X i X represents the amount of adsorbed gas signal obtained at time i. i-1 DX represents the amount of adsorbed gas signal obtained at the current time i-1. i This represents the first rate of change.

[0140] For example, the second rate of change can be expressed as: DY i =(Y i -Y i-1 ) / Y i , where Y i Y represents the amount of free gas signal obtained at time i. i-1 DY represents the amount of free gas signal obtained at the current time i-1.i This represents the second rate of change.

[0141] In this embodiment, the coal sample core is pretreated by vacuum drying at reservoir temperature to ensure the consistency of the initial state of the coal sample. Then, the coal sample is placed in a non-magnetic holder and a confining pressure consistent with the actual overburden stress is applied to simulate the real reservoir environment. Gas is injected until adsorption saturation, and then liquid is injected at the bottom hole pressure after fracturing and pump shutdown. The first relationship curve between signal intensity and decay time is obtained by periodic scanning with a nuclear magnetic resonance spectrometer. Based on the peak area of ​​the curve, the adsorbed and free gas signal quantities are accurately distinguished. Finally, the rate of change of the signal quantity is calculated to obtain the first coal sample information. The whole method closely follows the actual working conditions of coalbed methane wells, avoids detection errors caused by differences between experimental environment and field reservoir conditions, and achieves accurate identification and quantification of adsorbed and free gas signal quantities. This provides real and reliable basic data support for the subsequent determination of well shut-in time and improves the accuracy of the well shut-in time determination method.

[0142] Referring to Table 2, after the well simmering time reaches 60 hours, both the first and second change rates are less than the first threshold (3%). Therefore, the third duration corresponding to this coal sample core is 60 hours.

[0143] For example, if the third durations corresponding to 10 coal core samples are 60, 63, 66, 68, 69, 70, 71, 73, 75, and 76 hours respectively, the first duration is the maximum value among the 10 third durations, which is 76 hours (3.16 days).

[0144] Based on any of the above embodiments, the following, in conjunction with Figure 5 Methods for determining the range of simmering time for coal mines ( Figure 1 The embodiment of S104 will be described in detail.

[0145] Figure 5 A flowchart illustrating a method for determining a duration range provided in this application embodiment is available for detailed reference. Figure 5 The method may include:

[0146] S501. Determine the first permeability corresponding to the long core. The first permeability is the average permeability corresponding to multiple coal sample cores.

[0147] In one possible implementation, the first permeability corresponding to the long core can be obtained by adding the permeabilities corresponding to multiple coal sample cores that make up the long core, and then dividing the sum by the number of coal sample cores that make up the long core.

[0148] S502. Based on the first permeability and the second duration, determine the upper limit of the well simmering time range.

[0149] In some implementations, the upper limit of the well-sealing time range is determined based on the first permeability and the second duration, and may include:

[0150] Based on the chart and the first permeability, the fracture density corresponding to the long core is determined. The chart is used to indicate the relationship between the first permeability and the fracture density. Based on the fracture density, the fracture spacing corresponding to the long core is determined. The length of the long core is obtained. Based on the fracture spacing, the second duration, and the length of the long core, the upper limit of the well shut-in duration range is determined.

[0151] For example, Figure 6 A schematic diagram of a drawing provided for an embodiment of this application, with reference to... Figure 6 The horizontal axis of the chart represents the first permeability, and the vertical axis represents the fracture density. Each diagonal line in the chart corresponds to a fixed fracture width value, serving as a reference line to help distinguish the relationship between the first permeability and fracture density under different fracture widths. The gray area in the chart refers to the matching range of permeability, fracture density, and fracture width commonly found in reservoirs after fracturing in actual engineering projects (or recommended).

[0152] Reference Figure 6 For example, with a crack width of 15 micrometers (μm), when the first permeability is 5mD, the crack density corresponding to this first permeability is 0.01 cracks / inch.

[0153] In one possible implementation, the fracture spacing corresponding to a long core can be expressed as S1 = 1 / W1, where W1 represents the fracture width and S1 represents the fracture spacing. For example, when the fracture density corresponding to the first permeability is 0.01 fractures / inch, the fracture spacing is 100 (1 / 0.01) inches, or 2.54 meters.

[0154] In one possible implementation, the length of a long core sample can be obtained by weighing, and the upper limit of the well-sealing time range can be expressed as:

[0155] Tm1=a×T1×S1 / L1

[0156] Where 'a' represents the first coefficient, which can be preset, for example, 0.5; 'T1' represents the second duration; 'S1' represents the fracture spacing; 'L1' represents the length of the long core; and 'Tm1' represents the upper limit of the well-clogging duration range.

[0157] For example, when the first coefficient is 0.5, the second duration is 180, the fracture spacing is 2.54 meters, and the length of the long core is 0.812 meters, the upper limit of the well-sealing duration is 11.7 (0.5×180×2.54 / 0.812) days.

[0158] S503. Determine the duration range based on the first duration and the upper limit of the duration range.

[0159] In one possible implementation, the lower limit of the well-sealing time range can be the first time range. Therefore, the time range can be determined based on the first time range and the upper limit of the time range.

[0160] For example, when the first duration is 3.16 days and the upper limit of the duration range is 11.7 days, the duration range is 3.16 days to 11.7 days.

[0161] In this embodiment, the first permeability of a long core is determined by averaging the permeability of multiple coal sample cores. This is then combined with a chart to precisely match the corresponding fracture density and spacing. The upper limit of the well-closing time is calculated based on the long core length, the second duration, and a coefficient formula. The range is defined with the first duration as the lower limit. This method correlates the permeability and fracture parameters of the laboratory long core with the fracturing characteristics of the reservoir in the field. It not only restores the longitudinal heterogeneity of the reservoir through the average permeability but also quantifies the impact of fracture spacing and long core length on the well-closing time using charts and formulas. This avoids subjective errors and makes the determination of the well-closing time range more closely aligned with the actual seepage patterns of the reservoir, improving the rationality and operability of the time range and providing a precise time reference for on-site construction.

[0162] Figure 7 This is a schematic diagram of a device for determining the simmering time of a coalbed methane well, provided as an embodiment of this application. Please refer to... Figure 7 The coalbed methane well shut-in time determination device 700 includes:

[0163] The first determining module 701, the second determining module 702, the third determining module 703, and the fourth determining module 704, wherein:

[0164] The first determining module 701 is used to determine the first coal sample information corresponding to multiple coal sample cores in the coal mine. The first coal sample information includes the first rate of change of the adsorbed gas signal quantity and the second rate of change of the free gas signal quantity corresponding to the coal sample core.

[0165] The second determining module 702 is used to determine the first duration based on a plurality of first rates of change and a plurality of second rates of change;

[0166] The third determining module 703 is used to determine the second duration corresponding to the long core after the combination of multiple coal sample cores. The second duration is the duration during which the pressure on the right side of the long core is stable when gas and liquid are injected on the left side of the long core.

[0167] The fourth determining module 704 is used to determine the duration range of the well simmering corresponding to the coal well based on the first duration and the second duration.

[0168] The coalbed methane well shut-in time determination device provided in this application embodiment can execute the technical solution shown in the above method embodiment. Its implementation principle and beneficial effects are similar, and will not be repeated here.

[0169] In one possible implementation, the second determining module 702 is specifically used for:

[0170] Determine multiple third durations where both the first and second rates of change are less than or equal to a first threshold;

[0171] The maximum value among multiple third durations is determined as the first duration.

[0172] In one possible implementation, the first determining module 701 is specifically used for:

[0173] Gas was injected into multiple coal core samples until the gas adsorption of the multiple coal core samples was saturated.

[0174] Liquid was injected into multiple coal core samples, and a first relationship curve was determined. The first relationship curve is used to indicate the relationship between the signal intensity of gas adsorption or ionization and a preset decay time.

[0175] Based on the first relationship curve, the adsorbed gas signal quantity and free gas signal quantity corresponding to multiple coal sample cores in the coal mine were determined;

[0176] Based on the adsorbed gas signal quantity and the free gas signal quantity, the first coal sample information corresponding to multiple coal sample cores is determined.

[0177] In one possible implementation, the third determining module 703 is specifically used for:

[0178] Gas was injected into the left side of the long core until the pressure on the right side of the long core stabilized;

[0179] Liquid was injected into the left side of the long core until the pressure on the right side of the long core stabilized, and the duration of liquid injection into the left side of the long core was defined as the second duration.

[0180] In one possible implementation, the coalbed methane well shut-in time determination device further includes a processing module 705, which is used for:

[0181] Vacuum drying was performed on multiple coal core samples.

[0182] Determine the permeability of multiple coal sample cores after vacuum drying treatment;

[0183] Based on permeability, multiple coal core samples were combined to obtain a long core.

[0184] In one possible implementation, the fourth determining module 704 is specifically used for:

[0185] Determine the first permeability corresponding to the long core sample; the first permeability is the average permeability corresponding to multiple coal sample core samples.

[0186] Based on the first permeability and the second duration, the upper limit of the well-sealing duration range is determined;

[0187] The duration range is determined based on the first duration and the upper limit of the duration range.

[0188] In one possible implementation, the fourth determining module 704 is specifically used for:

[0189] Based on the chart and the first permeability, the fracture density corresponding to the long core is determined. The chart is used to indicate the relationship between the first permeability and the fracture density.

[0190] Determine the fracture spacing corresponding to the long core based on the fracture density;

[0191] Obtain the length of the long core sample;

[0192] The upper limit of the well-clogging time range is determined based on the fracture spacing, the second duration, and the length of the long core.

[0193] The coalbed methane well shut-in time determination device provided in this application embodiment can execute the technical solution shown in the above method embodiment. Its implementation principle and beneficial effects are similar, and will not be repeated here.

[0194] Figure 8 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Figure 8 As shown, the electronic device 800 may include: a transceiver 801, a processor 802, and a memory 803.

[0195] Processor 802 executes computer execution instructions stored in memory, causing processor 802 to perform the scheme in the above embodiments. Processor 802 can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0196] The memory 803 is connected to the processor 802 via the system bus and completes communication between them. The memory 803 is used to store computer program instructions.

[0197] Transceiver 801 can be used to obtain the task to be run and its configuration information.

[0198] The system bus can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. The system bus can be divided into address bus, data bus, control bus, etc. For ease of representation, only one thick line is used in the diagram, but this does not indicate that there is only one bus or one type of bus. Transceivers are used to enable communication between database access devices and other computers (e.g., clients, read-write libraries, and read-only libraries). Memory may include random access memory (RAM) and may also include non-volatile memory.

[0199] The electronic device provided in this application embodiment can be any device with on-device computing capabilities. For example, the electronic device can be a server, computer, or other such device, and this application embodiment does not limit this.

[0200] This application also provides a chip for executing instructions, which is used to execute the technical solution of the method for determining the simmering time of a coalbed methane well in the above embodiments.

[0201] This application also provides a computer-readable storage medium storing computer instructions. When the computer instructions are executed on a computer, the computer performs the technical solution of the method for determining the simmering time of a coalbed methane well as described above.

[0202] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative; for instance, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces, devices, or modules, and may be electrical, mechanical, or other forms.

[0203] The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to implement the solution of this embodiment according to actual needs.

[0204] Furthermore, the functional modules in the various embodiments of this application can be integrated into one processing unit, or each module can exist physically separately, or two or more modules can be integrated into one unit. The unit composed of the above modules can be implemented in hardware or in the form of hardware plus software functional units.

[0205] The integrated modules described above, implemented as software functional modules, can be stored in a computer-readable storage medium. These software functional modules, stored in a storage medium, include several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) or processor to execute some steps of the methods of the various embodiments of this application.

[0206] It should be understood that the aforementioned processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), etc. A general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in this invention can be directly manifested as execution by a hardware processor, or execution by a combination of hardware and software modules within the processor.

[0207] The memory may include high-speed RAM, and may also include non-volatile memory (NVM), such as at least one disk storage device, and may also be a USB flash drive, external hard drive, read-only memory, disk or optical disc, etc.

[0208] The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized as address buses, data buses, control buses, etc. For ease of illustration, the buses shown in the accompanying drawings are not limited to a single bus or a single type of bus.

[0209] The aforementioned storage media can be implemented from any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read-Only Memory (EPROM), Programmable Read-Only Memory (PROM), Read-Only Memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. The storage media can be any available medium accessible to general-purpose or special-purpose computers.

[0210] An exemplary storage medium is coupled to a processor, enabling the processor to read information from and write information to the storage medium. Alternatively, the storage medium can be an integral part of the processor. The processor and storage medium can reside in an Application Specific Integrated Circuit (ASIC). Alternatively, the processor and storage medium can exist as discrete components in an electronic control unit or main control device.

[0211] Those skilled in the art will understand that all or part of the steps of the above-described method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments; and the aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0212] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for determining the shut-in time of a coalbed methane well, characterized in that, The method includes: Determine the first coal sample information corresponding to multiple coal sample cores in a coal mine. The first coal sample information includes a first rate of change of the adsorbed gas signal quantity and a second rate of change of the free gas signal quantity corresponding to the coal sample core. The first duration is determined based on multiple first rates of change and multiple second rates of change; Determine the second duration corresponding to the long core after combining the multiple coal sample cores. The second duration is the duration during which the pressure on the right side of the long core is stable when gas and liquid are injected into the left side of the long core. Based on the first duration and the second duration, the duration range of the well simmering corresponding to the coal well is determined.

2. The method according to claim 1, characterized in that, The determination of the first duration based on multiple first rates of change and multiple second rates of change includes: Determine a plurality of third durations in which both the first rate of change and the second rate of change are less than or equal to a first threshold; The maximum value among the plurality of third durations is determined as the first duration.

3. The method according to claim 2, characterized in that, The determination of the first coal sample information corresponding to multiple coal core samples in the coal mine includes: Gas is injected into the multiple coal sample cores until the multiple coal sample cores are saturated with adsorbed gas. Liquid is injected into the multiple coal sample cores, and a first relationship curve is determined. The first relationship curve is used to indicate the relationship between the signal intensity of the gas adsorption or ionization and a preset decay time. Based on the first relationship curve, the adsorbed gas signal quantity and free gas signal quantity corresponding to multiple coal sample cores in the determined coal well are determined; Based on the adsorbed gas signal quantity and the free gas signal quantity, the information of the first coal sample corresponding to the multiple coal sample cores is determined.

4. The method according to claim 1, characterized in that, The determination of the second duration corresponding to the long core after combining the multiple coal sample cores includes: Gas is injected into the left side of the long core until the pressure on the right side of the long core stabilizes; Liquid is injected into the left side of the long core until the pressure on the right side of the long core stabilizes, and the duration of the injection of liquid into the left side of the long core is defined as the second duration.

5. The method according to claim 1, characterized in that, The method further includes: The multiple coal sample cores were subjected to vacuum drying treatment; Determine the permeability of the multiple coal sample cores after vacuum drying treatment; Based on permeability, the multiple coal sample cores are combined to obtain the long core.

6. The method according to claim 1, characterized in that, The step of determining the shut-in time range corresponding to the coal well based on the first time duration and the second time duration includes: Determine the first permeability corresponding to the long core, where the first permeability is the average of the permeabilities corresponding to the plurality of coal sample cores; Based on the first permeability and the second duration, determine the upper limit of the well shut-in duration range; The duration range is determined based on the first duration and the upper limit of the duration range.

7. The method according to claim 6, characterized in that, Determining the upper limit of the well-sealing time range based on the first permeability and the second duration includes: Based on the chart and the first permeability, the fracture density corresponding to the long core is determined, and the chart is used to indicate the relationship between the first permeability and the fracture density. Based on the fracture density, the fracture spacing corresponding to the long core is determined; Obtain the length of the long core sample; Based on the fracture spacing, the second duration, and the length of the long core, the upper limit of the well-clogging duration range is determined.

8. A device for determining the shut-in time of a coalbed methane well, characterized in that, include: The first determining module, the second determining module, the third determining module, and the fourth determining module, wherein: The first determining module is used to determine the first coal sample information corresponding to multiple coal sample cores in the coal mine. The first coal sample information includes a first rate of change of the adsorbed gas signal quantity and a second rate of change of the free gas signal quantity corresponding to the coal sample core. The second determining module is used to determine the first duration based on a plurality of first rates of change and a plurality of second rates of change; The third determining module is used to determine the second duration corresponding to the long core after the combination of the multiple coal sample cores. The second duration is the duration during which the pressure on the right side of the long core remains stable when gas and liquid are injected into the left side of the long core. The fourth determining module is used to determine the duration range of the well simmering corresponding to the coal well based on the first duration and the second duration.

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