Method, device and storage medium for screening shale gas layers

Abstract

The embodiment of the present application discloses a screening method, device and storage medium for shale gas layers, which belongs to the field of exploration technology. The method includes: determining the corrected porosity of the target shale gas layer according to the well logging data corresponding to the target shale gas layer; determining the formation pore pressure coefficient of the target shale gas layer based on the corrected porosity of the target shale gas layer; when the formation pore pressure coefficient is greater than a reference value, determining the target shale gas layer as a shale gas layer to be developed. In the embodiment of the present application, since the corrected porosity of the determined target shale gas layer refers to the porosity of other pores except organic pores, the influence of abnormal high pressure caused by hydrocarbon generation and expulsion of organic matter in the target shale gas layer can be eliminated. In this way, the formation pore pressure coefficient of the target shale gas layer determined by the corrected porosity will be more in line with the actual situation, so that it can be more accurately determined whether the target shale gas layer is a layer to be developed based on the formation pore pressure coefficient.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of exploration technology, and in particular to a screening method, device and storage medium for shale gas layers. Background Art

[0002] The formation pore pressure coefficient is an important parameter reflecting the preservation conditions of shale gas reservoirs and an important basis for evaluating the prospect of shale gas resources in a region. Therefore, studying the formation pore pressure coefficient of shale gas layers is of great significance to shale gas exploration and development. For example, the shale gas layers to be developed can be selected based on the formation pore pressure coefficient of the shale gas layers. Among them, the formation pore pressure coefficient refers to the ratio of the stress borne by the fluid in the formation pores to the hydrostatic pressure.

[0003] In related technologies, the normal compaction trend line is obtained through the logging curve, and then the normal compaction trend line method is used to determine the formation pore pressure coefficient of the shale gas layer. Under normal compaction conditions, the vertical effective stress of the mud shale gradually increases with the increase of burial depth, and the porosity decreases. When the mud shale formation undergoes unbalanced compaction, the pore pressure increases, while the effective stress decreases and the porosity increases. In this way, the formation pore pressure coefficient can be predicted based on the abnormal changes in the porosity of the mud shale formation, and then the development of the shale gas layer can be guided based on the formation pore pressure coefficient.

[0004] However, on the one hand, the difference in mineral components in shale gas layers can easily cause deviations in logging curves, and thus cause deviations in the positive production compaction trend line; on the other hand, the abnormally high pressure of some shales is no longer mainly due to unbalanced compaction, but may also be affected by the abnormally high hydrocarbon generation and expulsion of organic matter in the shales. Therefore, there is a deviation in the formation pore pressure coefficient determined by the above method. Summary of the invention

[0005] The present application provides a shale gas layer screening method, device and storage medium, which can effectively eliminate the influence of hydrocarbon generation and expulsion of organic matter and improve the accuracy of determining the shale gas layer to be developed. The technical solution is as follows:

[0006] In a first aspect, a method for screening shale gas layers is provided, the method comprising:

[0007] Determine the corrected porosity of the target shale gas layer according to the well logging data corresponding to the target shale gas layer, wherein the corrected porosity refers to the porosity of pores other than organic pores in the target shale gas layer;

[0008] Determining a formation pore pressure coefficient of the target shale gas layer based on the corrected porosity of the target shale gas layer;

[0009] When the formation pore pressure coefficient is greater than a reference value, the target shale gas layer is determined as a shale gas layer to be developed.

[0010] Optionally, determining the corrected porosity of the target shale gas layer according to the well logging data corresponding to the target shale gas layer includes:

[0011] Determine the total organic carbon content and total porosity of the target shale gas layer according to the well logging data;

[0012] The total porosity is corrected according to the total organic carbon content to obtain the corrected porosity of the target shale gas layer.

[0013] Optionally, the total porosity is corrected according to the total organic carbon content to obtain the corrected porosity of the target shale gas layer, including:

[0014] Determining the total porosity of organic pores in the target shale gas layer according to the total organic carbon content;

[0015] The difference between the total porosity and the total porosity of the organic pores is determined as the corrected porosity of the target shale gas layer.

[0016] Optionally, determining the total porosity of organic pores in the target shale gas layer according to the total organic carbon content includes:

[0017] Based on the total organic carbon content, determining the total porosity of organic pores in the target shale gas layer according to a first conversion formula;

[0018] The first conversion formula: POR O =a1×TOC

[0019] Among them, in the first conversion formula, POR O It refers to the total porosity of organic pores in the target shale gas layer; TOC refers to the total organic carbon content; a1 refers to the first parameter.

[0020] Optionally, before determining the total porosity of organic pores in the target shale gas layer based on the total organic carbon content according to the first conversion formula, the method further includes:

[0021] Obtaining the organic carbon content and organic pore porosity of each of a plurality of core samples, wherein the plurality of core samples are obtained by sampling shale gas layers at different depths, and the sampling depths of the plurality of core samples are all different;

[0022] The organic carbon content and the organic pore porosity of the plurality of core samples are fitted to obtain the first conversion formula.

[0023] Optionally, determining the formation pore pressure coefficient of the target shale gas layer based on the corrected porosity of the target shale gas layer includes:

[0024] Determining the formation effective stress of the target shale gas layer based on the corrected porosity of the target shale gas layer;

[0025] The formation effective stress of the target shale gas layer is converted to obtain the formation pore pressure coefficient of the target shale gas layer.

[0026] Optionally, determining the formation effective stress of the target shale gas layer based on the corrected porosity of the target shale gas layer includes:

[0027] Based on the corrected porosity of the target shale gas layer, determining the formation effective stress of the target shale gas layer according to a second conversion formula;

[0028] The second conversion formula:

[0029] Among them, in the second conversion formula, σ refers to the effective formation stress of the target shale gas layer; POR refers to the corrected porosity of the target shale gas layer; a2 refers to the second parameter; and a3 refers to the third parameter.

[0030] Optionally, before determining the formation effective stress of the target shale gas layer according to the second conversion formula based on the corrected porosity of the target shale gas layer, the method further includes:

[0031] Obtaining sampling depths of a plurality of core samples, wherein the plurality of core samples are obtained by sampling shale gas layers at different depths, and the sampling depths of the plurality of core samples are all different;

[0032] Determine the overburden pressure of each core sample based on the sampling depths of the multiple core samples to obtain multiple overburden pressures;

[0033] Selecting multiple effective stresses ranging from zero pressure to half the maximum overburden pressure;

[0034] Acquire multiple porosities corresponding to each core sample based on the multiple effective stresses;

[0035] Normalizing the porosities of the multiple core samples, and performing mean processing on the multiple normalized porosities of each core sample to obtain multiple average porosities corresponding to the multiple effective stresses;

[0036] The second conversion formula is obtained by performing exponential curve fitting on the multiple effective stresses and the multiple average porosities.

[0037] In a second aspect, a shale gas layer screening device is provided, the device comprising:

[0038] A first determination module is used to determine the corrected porosity of the target shale gas layer according to the well logging data corresponding to the target shale gas layer, wherein the corrected porosity refers to the porosity of pores other than organic pores in the target shale gas layer;

[0039] A second determination module is used to determine a formation pore pressure coefficient of the target shale gas layer based on the corrected porosity of the target shale gas layer;

[0040] The third determination module is used to determine the target shale gas layer as a shale gas layer to be developed when the formation pore pressure coefficient is greater than a reference value.

[0041] Optionally, the first determining module includes:

[0042] A first determination unit, configured to determine the total organic carbon content and total porosity of the target shale gas layer according to the well logging data;

[0043] A correction unit is used to correct the total porosity according to the total organic carbon content to obtain the corrected porosity of the target shale gas layer.

[0044] Optionally, the correction unit is mainly used for:

[0045] Determining the total porosity of organic pores in the target shale gas layer according to the total organic carbon content;

[0046] The difference between the total porosity and the total porosity of the organic pores is determined as the corrected porosity of the target shale gas layer.

[0047] Optionally, the correction unit is further used for:

[0048] Based on the total organic carbon content, determining the total porosity of organic pores in the target shale gas layer according to a first conversion formula;

[0049] The first conversion formula: POR O =a1×TOC

[0050] Among them, in the first conversion formula, POR O It refers to the total porosity of organic pores in the target shale gas layer; TOC refers to the total organic carbon content; a1 refers to the first parameter.

[0051] Optionally, the correction unit is further used for:

[0052] Obtaining the organic carbon content and organic pore porosity of each of a plurality of core samples, wherein the plurality of core samples are obtained by sampling shale gas layers at different depths, and the sampling depths of the plurality of core samples are all different;

[0053] The organic carbon content and the organic pore porosity of the plurality of core samples are fitted to obtain the first conversion formula.

[0054] Optionally, the second determining module includes:

[0055] A second determining unit, configured to determine the formation effective stress of the target shale gas layer based on the corrected porosity of the target shale gas layer;

[0056] The conversion unit is used to convert the formation effective stress of the target shale gas layer to obtain the formation pore pressure coefficient of the target shale gas layer.

[0057] Optionally, the second determining unit is mainly used for:

[0058] Based on the corrected porosity of the target shale gas layer, determining the formation effective stress of the target shale gas layer according to a second conversion formula;

[0059] The second conversion formula:

[0060] Among them, in the second conversion formula, σ refers to the effective formation stress of the target shale gas layer; POR refers to the corrected porosity of the target shale gas layer; a2 refers to the second parameter; and a3 refers to the third parameter.

[0061] Optionally, the second determining unit is mainly used for:

[0062] Obtaining sampling depths of a plurality of core samples, wherein the plurality of core samples are obtained by sampling shale gas layers at different depths, and the sampling depths of the plurality of core samples are all different;

[0063] Determine the overburden pressure of each core sample based on the sampling depths of the multiple core samples to obtain multiple overburden pressures;

[0064] Selecting multiple effective stresses ranging from zero pressure to half the maximum overburden pressure;

[0065] Acquire multiple porosities corresponding to each core sample based on the multiple effective stresses;

[0066] Normalizing the porosities of the multiple core samples, and performing mean processing on the multiple normalized porosities of each core sample to obtain multiple average porosities corresponding to the multiple effective stresses;

[0067] The second conversion formula is obtained by performing exponential curve fitting on the multiple effective stresses and the multiple average porosities.

[0068] According to a third aspect, a computer-readable storage medium is provided, wherein a computer program is stored in the storage medium, and when the computer program is executed by a processor, any one of the methods provided in the first aspect is implemented.

[0069] The beneficial effects brought by the technical solution provided by the embodiment of the present application include at least:

[0070] In the embodiment of the present application, since the corrected porosity of the target shale gas layer to be determined refers to the porosity of pores other than organic pores, the influence of abnormal high pressure caused by hydrocarbon generation and expulsion of organic matter in the target shale gas layer can be eliminated. In this way, the formation pore pressure coefficient of the target shale gas layer determined by the corrected porosity will be more in line with the actual situation, avoiding the problem that the well logging curve cannot accurately evaluate the formation pore pressure of the shale gas reservoir due to the difference in mineral components in the shale gas layer when using the normal compaction trend line method, and then the formation pore pressure coefficient can be used to more accurately determine whether the target shale gas layer is a layer to be developed. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0072] Figure 1 It is a schematic diagram of a process of screening a shale gas layer provided in an embodiment of the present application;

[0073] Figure 2 This is a schematic diagram of the relationship between total organic carbon content and organic pore porosity provided in an embodiment of the present application;

[0074] Figure 3 is a schematic diagram of the relationship between effective stress and average porosity provided in an embodiment of the present application;

[0075] Figure 4 It is a schematic diagram of the relationship between the formation pore pressure coefficient determined by two methods provided in an embodiment of the present application;

[0076] Figure 5 It is a structural schematic diagram of a shale gas layer screening device provided in an embodiment of the present application;

[0077] Figure 6 It is a schematic structural diagram of another shale gas layer screening device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0078] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the implementation methods of the embodiments of the present application will be further described in detail below with reference to the accompanying drawings.

[0079] Figure 1 1 is a flow chart of a shale gas layer screening method provided in an embodiment of the present application. The method is applied to a terminal, which is a smart phone, a laptop computer, a desktop computer, etc. Figure 1 , the method comprises the following steps.

[0080] In the embodiment of the present application, since the formation pore pressure coefficient is an important parameter reflecting the preservation conditions of the shale gas reservoir, it is possible to determine whether the target shale gas layer is suitable for development based on the formation pore pressure coefficient of the target shale gas layer, that is, to determine whether the target shale gas layer has development value. Therefore, before determining whether the target shale gas layer is suitable for development, it is necessary to determine the formation pore pressure coefficient of the target shale gas layer. Since the formation pore pressure coefficient of the target shale gas layer depends on the attribute information and component information of the target shale gas layer, and the attribute information and component information of the target shale gas layer can be obtained based on the logging data corresponding to the target shale gas layer. Therefore, the logging data corresponding to the target shale gas layer can be obtained first, and then the formation pore pressure coefficient of the target shale gas layer can be determined according to the following steps 101-102.

[0081] The property information of the target shale gas layer includes the density value and the acoustic wave time difference of the target shale gas layer, and the component information of the target shale gas layer includes the uranium content value.

[0082] Step 101: Determine the corrected porosity of the target shale gas layer according to the well logging data corresponding to the target shale gas layer.

[0083] Among them, the corrected porosity refers to the porosity of pores other than organic pores in the target shale gas layer.

[0084] In some embodiments, the total organic carbon content and total porosity of the target shale gas layer are determined based on well logging data; the total porosity is corrected based on the total organic carbon content to obtain the corrected porosity of the target shale gas layer.

[0085] For the total organic carbon content of the target shale gas layer, the total organic carbon content of the gas reservoir block where the target shale gas layer is located and the first empirical formula established by fitting the logging curve are first obtained, and then the density value and uranium content value of the target shale gas layer are obtained according to the logging data. The density value and uranium content value of the target shale gas layer are then substituted into the first empirical formula to obtain the total organic carbon content of the target shale gas layer.

[0086] Among them, the first empirical formula is as follows: TOC = a × DEN + b × log (U) + c

[0087] Among them, in the first empirical formula, TOC refers to the total organic carbon content of the target shale gas layer; DEN refers to the density value of the target shale gas layer; U refers to the oil content value in the target shale gas layer; a refers to the first calculation parameter; b refers to the second calculation parameter; c refers to the third calculation parameter. The values ​​of a, b, and c are different in different gas reservoir blocks. For example, the value of a in the gas reservoir block where the target shale gas layer is located is -16.89, the value of b is 0.294, and the value of c is 45.367. The determined total organic carbon content is 3.5.

[0088] It should be noted that in addition to determining the total organic carbon content of the target shale gas layer by the above method, the total organic carbon content of the target shale gas layer can also be determined by other methods. For example, the logging data of the target shale gas layer also includes an inelastic gamma spectrum obtained by the element capture logging method. At this time, the inelastic gamma spectrum is interpreted to obtain the total organic carbon content of the target shale gas layer. Among them, the specific method of obtaining the total organic carbon content in the target shale gas layer by element capture logging data can refer to the relevant technology, and the embodiments of the present application are not limited to this.

[0089] For the total porosity of the target shale gas layer, the total porosity of the gas reservoir block where the target shale gas layer is located and the second empirical formula established by fitting the logging curve are first obtained, and then the density value, sonic time difference and uranium content value of the target shale gas layer are obtained according to the logging data. The density value, sonic time difference and uranium content value of the target shale gas layer are then substituted into the second empirical formula to obtain the total porosity of the target shale gas layer.

[0090] The second empirical formula is as follows: POR = d × DEN + f × AC + g × log (U) + h

[0091] Among them, in the second empirical formula, POR refers to the total porosity of the target shale gas layer; DEN refers to the density value of the target shale gas layer; AC refers to the acoustic time difference of the target shale gas layer; U refers to the oil content value in the target shale gas layer; d refers to the fourth calculation parameter; f refers to the fifth calculation parameter; g refers to the sixth calculation parameter; h refers to the seventh calculation parameter. The values ​​of d, f, g, and h are different in different gas reservoir blocks. For example, the value of d in the gas reservoir block where the target shale gas layer is located is -6.51, the value of f is 0.124, the value of g is 0.093, and the value of h is 12.98. The determined total porosity is 5.5.

[0092] It should be noted that in addition to determining the total porosity of the target shale gas layer by the above method, the total porosity of the target shale gas layer can also be determined by other methods. For example, the total porosity of the target shale gas layer is optimized according to the rock volume model. Among them, the method of optimizing the total porosity of the target shale gas layer can refer to the description of the relevant technology, and the embodiments of the present application will not be repeated.

[0093] For the corrected porosity of the target shale gas layer, the total porosity of the organic pores in the target shale gas layer can be first determined based on the total organic carbon content; and then the difference between the total porosity and the total porosity of the organic pores is determined as the corrected porosity of the target shale gas layer.

[0094] In the embodiment of the present application, after the organic matter generates and expel hydrocarbons, the gas will accumulate in the organic pores, and the content of organic matter can be expressed by the content of organic carbon. Therefore, there is a correlation between the content of organic carbon and the total porosity of the organic pores, that is, the amount of organic pores formed depends on the amount of organic carbon content.

[0095] Therefore, in some embodiments, a first conversion formula between the total organic carbon content and the total porosity of the organic pores may be determined first, and then the total porosity of the organic pores in the target shale gas layer may be determined according to the first conversion formula based on the total organic carbon content.

[0096] After the total porosity of organic pores in the target shale gas layer is determined, the difference between the total porosity and the total porosity of organic pores can be determined as the corrected porosity of the target shale gas layer to eliminate the influence of abnormally high pressure caused by hydrocarbon generation and expulsion by organic matter in the target shale gas layer.

[0097] It should be noted that the first conversion formula between the total organic carbon content and the total porosity of organic pores can be determined through the following steps (1)-(2).

[0098] (1) Obtain the organic carbon content and organic pore porosity of each core sample among multiple core samples.

[0099] The multiple core samples are obtained by sampling shale gas layers at different depths, and the sampling depths of the multiple core samples are all different. In addition, in order to ensure the accuracy of the determined first conversion formula, the total organic carbon content of the multiple core samples obtained is different, and the organic pore porosity of the multiple core samples is also different.

[0100] Optionally, for multiple shale gas layers at different depths, at least one core sample can be obtained from each shale gas layer, and then the organic carbon content and organic pore porosity of each core sample can be obtained, and then multiple core samples with different organic carbon contents and organic pore porosities can be selected from the core samples obtained from the multiple shale gas layers.

[0101] Among them, the organic carbon content and organic pore porosity of each core sample can be obtained under experimental conditions. For example, they can be obtained by slice observation under a field emission scanning electron microscope. The specific method of obtaining can refer to relevant technologies, and the embodiments of the present application are not limited to this.

[0102] (2) Fitting the organic carbon content and organic pore porosity of multiple core samples to obtain the first conversion formula.

[0103] Among them, the first conversion formula: POR O =a1×TOC

[0104] In the first conversion formula, POR O It refers to the total porosity of organic pores in the target shale gas layer; TOC refers to the total organic carbon content of the target shale gas layer; a1 refers to the first parameter. The value of a1 varies in different gas reservoir blocks. For example, 24 core samples are sampled and a rectangular coordinate system is established, with organic carbon content as the horizontal axis and organic pore porosity as the vertical axis, such as Figure 2 As shown, the organic carbon content and organic pore porosity of each core sample are marked in a rectangular coordinate system to obtain 24 coordinate points. The 24 points are then fitted using the least squares method to obtain the first conversion formula with an a1 value of 0.2068. The total porosity of organic pores in the target shale gas layer determined by the first conversion formula is 0.724. At this time, the corrected porosity obtained by correcting the total porosity of the target shale gas layer is 4.776.

[0105] Step 102: Determine the formation pore pressure coefficient of the target shale gas layer based on the corrected porosity of the target shale gas layer.

[0106] Optionally, the formation effective stress of the target shale gas layer is determined based on the corrected porosity of the target shale gas layer; the formation effective stress of the target shale gas layer is converted to obtain the formation pore pressure coefficient of the target shale gas layer.

[0107] Since there is a correlation between porosity and formation effective stress, the second conversion formula between porosity and formation effective stress can be determined first, and then the porosity is corrected based on the target shale gas layer, and the formation effective stress of the target shale gas layer is determined according to the second conversion formula.

[0108] After the formation effective stress of the target shale gas layer is obtained, the formation effective stress of the target shale gas layer can be converted into the pore pressure coefficient of the target formation through the third conversion formula.

[0109] Among them, the third conversion formula is:

[0110] In the third conversion formula, P PIt refers to the formation pore pressure coefficient of the target shale gas layer; σ refers to the formation effective stress of the target shale gas layer; H refers to the depth of the target shale gas layer; ρ refers to the density value of the formation at different depths; g refers to the unit of gravity, which is a constant of 9.8 Newtons / kilograms.

[0111] It should be noted that the second conversion formula between the total organic carbon content and the total porosity of organic pores can be determined in the following manner.

[0112] The sampling depths of multiple core samples are obtained, wherein the multiple core samples are obtained by sampling shale gas layers at different depths, and the sampling depths of the multiple core samples are different; based on the sampling depths of the multiple core samples, the overburden pressure of each core sample is determined to obtain multiple overburden pressures; multiple effective stresses are selected within a range from zero pressure to half of the maximum overburden pressure; multiple porosities corresponding to each core sample are obtained based on the multiple effective stresses; the porosities of the multiple core samples are normalized, and the multiple normalized porosities of each core sample are averaged to obtain multiple average porosities corresponding to the multiple effective stresses; exponential curve fitting is performed on the multiple effective stresses and the multiple average porosities to obtain a second conversion formula.

[0113] Among them, for the overburden pressure of each core sample, the logging data of the corresponding depth can be obtained in the logging data according to the sampling depth of the core sample, and then the overburden pressure of the core sample can be determined based on the logging data. The specific method of obtaining the overburden pressure based on the logging data can refer to the relevant technology, and the embodiments of this application are not limited to this.

[0114] Among them, 4 to 8 pressure values ​​can be uniformly selected as the selected effective stresses in the range from zero pressure to half of the maximum overburden pressure. For the method of obtaining the porosity of each core sample under each effective stress, reference can be made to "SY / T6385-2016 Method for Determining Rock Porosity and Permeability under Overburden Pressure", which is not limited in the embodiments of this application.

[0115] Among them, the second conversion formula is:

[0116] In the second conversion formula, σ refers to the formation effective stress of the target shale gas layer; POR refers to the modified porosity of the target shale gas layer; a2 refers to the second parameter; and a3 refers to the third parameter. The values ​​of a2 and a3 are different in different gas reservoir blocks. For example, 24 core samples are sampled, and 8 effective stresses of each core sample and the average porosity corresponding to each effective stress are obtained. Then a rectangular coordinate system is established, and the average porosity is used as the horizontal axis and the effective stress is used as the vertical axis. The 8 effective stresses and the corresponding average porosities are marked in the rectangular coordinate system, such as Figure 3As shown, 8 coordinate points are obtained, and then fitting is performed to obtain the second conversion formula with a2 value of 0.214.61 and a3 value of -0.482; the depth of the target shale gas layer is 2505 meters, and after converting the formation effective stress of the target shale gas layer by the third conversion formula, the formation pore pressure coefficient of the target shale gas layer is 1.685.

[0117] The first conversion formula and the second conversion formula can be obtained at the same time, or the first conversion formula can be obtained first and then the second conversion formula; or the second conversion formula can be obtained first and then the first conversion formula. Since multiple core samples need to be obtained when obtaining the first conversion formula and the second conversion formula, in order to avoid the repeatability of core sample sampling, multiple core samples can be obtained at one time, and then the first conversion formula and the second conversion formula can be obtained simultaneously based on the multiple core samples obtained.

[0118] In actual use, for 24 different shale gas layers, 24 formation pore pressure coefficients are determined by the method provided in the embodiment of the present application; and 24 formation pore pressure coefficients are obtained by cable formation testing technology (XPT) to obtain two formation pore pressure coefficients for each of the 24 shale gas layers. A coordinate system is established, and the formation pore pressure coefficient obtained by cable formation testing technology is used as the horizontal coordinate, and the formation pore pressure coefficient determined by the method provided in the embodiment of the present application is used as the vertical coordinate, and the formation pore pressure coefficient of each shale gas layer is marked in the rectangular coordinate system according to the acquisition method, such as Figure 4 At this time, the correlation coefficient between the 24 formation pore pressure coefficients determined by the method provided in the embodiment of the present application and the 24 formation pore pressure coefficients obtained by the cable formation testing technology (XPT) is approximately equal to 1, which shows the accuracy of the formation pore pressure coefficient determined by the embodiment of the present application, and the convenience and speed of the method provided by the embodiment of the present application compared with the cable formation testing technology.

[0119] Step 103: When the formation pore pressure coefficient is greater than a reference value, the target shale gas layer is determined as a shale gas layer to be developed.

[0120] After the formation pore pressure coefficient of the target shale gas layer is determined in combination with the above step 102, since the larger the formation pore pressure coefficient, the more gas is contained in the formation pores, it can be determined whether the target shale gas layer is a shale gas layer to be developed based on the size of the formation pore pressure coefficient.

[0121] Optionally, the formation pore pressure coefficient of the target shale gas layer is compared with a reference value. If the formation pore pressure coefficient is greater than the reference value, the target shale gas layer is determined to be a shale gas layer to be developed; conversely, if the formation pore pressure coefficient is less than or equal to the reference value, the target shale gas layer is determined to be unsuitable for development.

[0122] For example, the reference value is 1.2 or 1.5. 1.2 or 1.5 is just an example of a reference value, and the reference value may also be other values, which is not limited in the embodiments of the present application.

[0123] In the embodiment of the present application, since the corrected porosity of the determined target shale gas layer refers to the porosity of pores other than organic pores, the influence of abnormal high pressure caused by hydrocarbon generation and expulsion of organic matter in the target shale gas layer can be eliminated. In this way, the formation pore pressure coefficient of the target shale gas layer determined by the corrected porosity will be more in line with the actual situation, so that it can be more accurately determined whether the target shale gas layer is a layer to be developed based on the formation pore pressure coefficient. In addition, in the embodiment of the present application, no special instrument measurement or small-scale fracturing test is required, making the determination of the formation pore pressure coefficient of the target shale gas layer simpler and more efficient.

[0124] Figure 5 is a schematic diagram of the structure of a shale gas layer screening device provided in an embodiment of the present application, the device is integrated in a smart phone, a laptop computer, a desktop computer, etc. Figure 5 , the device comprises:

[0125] The first determination module 501 is used to determine the corrected porosity of the target shale gas layer according to the well logging data corresponding to the target shale gas layer, where the corrected porosity refers to the porosity of pores other than organic pores in the target shale gas layer;

[0126] A second determination module 502 is used to determine a formation pore pressure coefficient of the target shale gas layer based on the corrected porosity of the target shale gas layer;

[0127] The third determination module 503 is used to determine the target shale gas layer as a shale gas layer to be developed when the formation pore pressure coefficient is greater than a reference value.

[0128] Optionally, the first determining module 501 includes:

[0129] A first determination unit is used to determine the total organic carbon content and total porosity of the target shale gas layer according to the well logging data;

[0130] The correction unit is used to correct the total porosity according to the total organic carbon content to obtain the corrected porosity of the target shale gas layer.

[0131] Optionally, the correction unit is mainly used to:

[0132] Determine the total porosity of organic pores in the target shale gas layer based on the total organic carbon content;

[0133] The difference between the total porosity and the total porosity of organic pores is determined as the corrected porosity of the target shale gas formation.

[0134] Optionally, the correction unit is further configured to:

[0135] Based on the total organic carbon content, determining the total porosity of organic pores in the target shale gas layer according to a first conversion formula;

[0136] First conversion formula: POR O =a1×TOC

[0137] Among them, in the first conversion formula, POR O It refers to the total porosity of organic pores in the target shale gas layer; TOC refers to the total organic carbon content of the target shale gas layer; a1 refers to the first parameter.

[0138] Optionally, the correction unit is further configured to:

[0139] Obtaining the organic carbon content and the organic pore porosity of each of the multiple core samples, wherein the multiple core samples are obtained by sampling shale gas layers at different depths, and the sampling depths of the multiple core samples are all different;

[0140] The organic carbon content and organic pore porosity of multiple core samples were fitted to obtain the first conversion formula.

[0141] Optionally, the second determining module 502 includes:

[0142] A second determination unit is used to determine the formation effective stress of the target shale gas layer based on the corrected porosity of the target shale gas layer;

[0143] The conversion unit is used to convert the formation effective stress of the target shale gas layer to obtain the formation pore pressure coefficient of the target shale gas layer.

[0144] Optionally, the second determining unit is mainly used for:

[0145] Based on the corrected porosity of the target shale gas layer, determining the formation effective stress of the target shale gas layer according to a second conversion formula;

[0146] Second conversion formula:

[0147] Wherein, in the second conversion formula, σ refers to the formation effective stress of the target shale gas layer; POR refers to the corrected porosity of the target shale gas layer; a2 refers to the second parameter; and a3 refers to the third parameter.

[0148] Optionally, the second determining unit is mainly used for:

[0149] Obtaining sampling depths of multiple core samples, where the multiple core samples are obtained by sampling shale gas layers at different depths, and the sampling depths of the multiple core samples are all different;

[0150] Based on the sampling depths of the multiple core samples, the overburden pressure of each core sample is determined to obtain multiple overburden pressures;

[0151] Selecting multiple effective stresses ranging from zero pressure to half the maximum overburden pressure;

[0152] Obtain multiple porosities corresponding to each core sample based on multiple effective stresses;

[0153] Normalizing the porosities of multiple core samples, and averaging multiple normalized porosities of each core sample to obtain multiple average porosities corresponding to multiple effective stresses;

[0154] The second conversion formula is obtained by performing exponential curve fitting on multiple effective stresses and multiple average porosities.

[0155] In the embodiment of the present application, since the corrected porosity of the target shale gas layer determined refers to the porosity of pores other than organic pores, the influence of abnormal high pressure caused by hydrocarbon generation and expulsion of organic matter in the target shale gas layer can be eliminated. In this way, the formation pore pressure coefficient of the target shale gas layer determined by the corrected porosity will be more consistent with the actual situation, so that whether the target shale gas layer is a layer to be developed can be more accurately determined based on the formation pore pressure coefficient.

[0156] It should be noted that: the shale gas layer screening device provided in the above embodiment only uses the division of the above functional modules as an example when screening the shale gas layer to be developed. In actual applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device is divided into different functional modules to complete all or part of the functions described above. In addition, the shale gas layer screening device provided in the above embodiment and the shale gas layer screening method embodiment belong to the same concept. The specific implementation process is detailed in the method embodiment and will not be repeated here.

[0157] Figure 6 FIG. 6 is a block diagram showing a structure of a terminal 600 provided by an exemplary embodiment of the present application. Figure 6 The terminal 600 may be a smart phone, a tablet computer, a laptop computer or a desktop computer. The terminal 600 may also be called a user equipment, a portable terminal, a laptop terminal, a desktop terminal or other names. Figure 6 , the terminal 600 may include a processor 601 and a memory 602 .

[0158] The processor 601 may include one or more processing cores, such as a 4-core processor, an 8-core processor, etc. The processor 601 may be implemented in at least one hardware form of DSP (Digital Signal Processing), FPGA (Field-Programmable Gate Array), and PLA (Programmable Logic Array). The processor 601 may also include a main processor and a coprocessor. The main processor is a processor for processing data in the awake state, also known as a CPU (Central Processing Unit); the coprocessor is a low-power processor for processing data in the standby state. In some embodiments, the processor 601 may be integrated with a GPU (Graphics Processing Unit), which is responsible for rendering and drawing the content to be displayed on the display screen. In some embodiments, the processor 601 may also include an AI (Artificial Intelligence) processor, which is used to process computing operations related to machine learning.

[0159] The memory 602 may include one or more computer-readable storage media, which may be non-transitory. The memory 602 may also include a high-speed random access memory, and a non-volatile memory, such as one or more disk storage devices, flash memory storage devices. In some embodiments, the non-transitory computer-readable storage medium in the memory 602 is used to store at least one instruction, which is used to be executed by the processor 601 to implement a shale gas layer screening method provided in the method embodiment of the present application.

[0160] In some embodiments, the terminal 600 may further optionally include: a peripheral device interface 603 and at least one peripheral device. The processor 601, the memory 602 and the peripheral device interface 603 may be connected via a bus or a signal line. Each peripheral device may be connected to the peripheral device interface 603 via a bus, a signal line or a circuit board. Specifically, the peripheral device includes: at least one of a radio frequency circuit 604, a display screen 605, a positioning component 606 and a power supply 607.

[0161] The peripheral device interface 603 may be used to connect at least one peripheral device related to I / O (Input / Output) to the processor 601 and the memory 602. In some embodiments, the processor 601, the memory 602, and the peripheral device interface 603 are integrated on the same chip or circuit board; in some other embodiments, any one or two of the processor 601, the memory 602, and the peripheral device interface 603 may be implemented on a separate chip or circuit board, which is not limited in this embodiment.

[0162] The radio frequency circuit 604 is used to receive and transmit RF (Radio Frequency) signals, also known as electromagnetic signals. The radio frequency circuit 604 communicates with the communication network and other communication devices through electromagnetic signals. The radio frequency circuit 604 converts the electrical signal into an electromagnetic signal for transmission, or converts the received electromagnetic signal into an electrical signal. Optionally, the radio frequency circuit 604 includes: an antenna system, an RF transceiver, one or more amplifiers, a tuner, an oscillator, a digital signal processor, a codec chipset, a user identity module card, etc. The radio frequency circuit 604 can communicate with other terminals through at least one wireless communication protocol. The wireless communication protocol includes but is not limited to: the World Wide Web, a metropolitan area network, an intranet, various generations of mobile communication networks (2G, 3G, 4G and 5G), a wireless local area network and / or a WiFi (Wireless Fidelity) network. In some embodiments, the radio frequency circuit 604 may also include circuits related to NFC (Near Field Communication), which is not limited in this application.

[0163] The display screen 605 is used to display the UI (User Interface). The UI may include graphics, text, icons, videos and any combination thereof. When the display screen 605 is a display screen, the display screen 605 also has the ability to collect touch signals on the surface or above the surface of the display screen 605. The touch signal can be input to the processor 601 as a control signal for processing. At this time, the display screen 605 can also be used to provide virtual buttons and / or virtual keyboards, also known as soft buttons and / or soft keyboards. In some embodiments, the display screen 605 can be one, and the front panel of the terminal 600 is set; in other embodiments, the display screen 605 can be at least two, which are respectively set on different surfaces of the terminal 600 or are folded; in some other embodiments, the display screen 605 can be a flexible display screen, which is set on the curved surface or folded surface of the terminal 600. Even, the display screen 605 can also be set to a non-rectangular irregular shape, that is, a special-shaped screen. The display screen 605 can be made of materials such as LCD (Liquid Crystal Display), OLED (Organic Light-Emitting Diode, organic light-emitting diode).

[0164] The positioning component 606 is used to locate the current geographical location of the terminal 600 to implement navigation or LBS (Location Based Service). The positioning component 606 can be a positioning component based on the US GPS (Global Positioning System), China's Beidou system or Russia's Galileo system.

[0165] The power supply 607 is used to power various components in the terminal 600. The power supply 607 can be an alternating current, a direct current, a disposable battery, or a rechargeable battery. When the power supply 607 includes a rechargeable battery, the rechargeable battery can be a wired rechargeable battery or a wireless rechargeable battery. A wired rechargeable battery is a battery charged through a wired line, and a wireless rechargeable battery is a battery charged through a wireless coil. The rechargeable battery can also be used to support fast charging technology.

[0166] Those skilled in the art will understand that Figure 6 The structure shown in the figure does not constitute a limitation on the terminal 600, and the terminal 600 may include more or less components than those shown in the figure, or combine some components, or adopt a different component arrangement.

[0167] In the above embodiment, a non-transitory computer-readable storage medium including instructions is also provided, the computer-readable storage medium is used to store at least one instruction, the at least one instruction is used to be executed by the processor to implement the above Figure 1 The method provided by the illustrated embodiment.

[0168] A person skilled in the art will understand that all or part of the steps to implement the above embodiments may be accomplished by hardware or by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, and the above-mentioned storage medium may be a read-only memory, a disk or an optical disk, etc.

[0169] The above description is only an optional embodiment of the embodiments of the present application and is not intended to limit the embodiments of the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present application should be included in the protection scope of the embodiments of the present application.

Claims

1. A method for screening shale gas layers, characterized in that: The method comprises: Determine the corrected porosity of the target shale gas layer according to the well logging data corresponding to the target shale gas layer, wherein the corrected porosity refers to the porosity of pores other than organic pores in the target shale gas layer; Determining a formation pore pressure coefficient of the target shale gas layer based on the corrected porosity of the target shale gas layer; When the formation pore pressure coefficient is greater than a reference value, determining the target shale gas layer as a shale gas layer to be developed; Wherein, determining the formation pore pressure coefficient of the target shale gas layer based on the corrected porosity of the target shale gas layer includes: Based on the corrected porosity of the target shale gas layer, determining the formation effective stress of the target shale gas layer according to a second conversion formula; The second conversion formula: Among them, in the second conversion formula, refers to the formation effective stress of the target shale gas layer; refers to the modified porosity of the target shale gas formation; refers to the second parameter; refers to the third parameter; Converting the formation effective stress of the target shale gas layer to obtain the formation pore pressure coefficient of the target shale gas layer; Before determining the formation effective stress of the target shale gas layer according to the second conversion formula based on the corrected porosity of the target shale gas layer, the method further includes: Obtaining sampling depths of a plurality of core samples, wherein the plurality of core samples are obtained by sampling shale gas layers at different depths, and the sampling depths of the plurality of core samples are all different; Determine the overburden pressure of each core sample based on the sampling depths of the multiple core samples to obtain multiple overburden pressures; Selecting multiple effective stresses ranging from zero pressure to half the maximum overburden pressure; Acquire multiple porosities corresponding to each core sample based on the multiple effective stresses; Normalizing the porosities of the multiple core samples, and performing mean processing on the multiple normalized porosities of each core sample to obtain multiple average porosities corresponding to the multiple effective stresses; The second conversion formula is obtained by performing exponential curve fitting on the multiple effective stresses and the multiple average porosities.

2. The method according to claim 1, characterized in that Determining the corrected porosity of the target shale gas layer according to the well logging data corresponding to the target shale gas layer includes: Determine the total organic carbon content and total porosity of the target shale gas layer according to the well logging data; The total porosity is corrected according to the total organic carbon content to obtain the corrected porosity of the target shale gas layer.

3. The method according to claim 2, characterized in that The step of correcting the total porosity according to the total organic carbon content to obtain the corrected porosity of the target shale gas layer includes: Determining the total porosity of organic pores in the target shale gas layer according to the total organic carbon content; The difference between the total porosity and the total porosity of the organic pores is determined as the corrected porosity of the target shale gas layer.

4. The method according to claim 3, characterized in that Determining the total porosity of organic pores in the target shale gas layer according to the total organic carbon content includes: Based on the total organic carbon content, determining the total porosity of organic pores in the target shale gas layer according to a first conversion formula; The first conversion formula: Among them, in the first conversion formula, It refers to the total porosity of organic pores in the target shale gas layer; refers to the total organic carbon content; Refers to the first parameter.

5. The method according to claim 4, characterized in that Before determining the total porosity of organic pores in the target shale gas layer according to the first conversion formula based on the total organic carbon content, the method further includes: Obtaining the organic carbon content and organic pore porosity of each of a plurality of core samples, wherein the plurality of core samples are obtained by sampling shale gas layers at different depths, and the sampling depths of the plurality of core samples are all different; The organic carbon content and the organic pore porosity of the plurality of core samples are fitted to obtain the first conversion formula.

6. A shale gas layer screening device, characterized in that: The device comprises: A first determination module is used to determine the corrected porosity of the target shale gas layer according to the well logging data corresponding to the target shale gas layer, wherein the corrected porosity refers to the porosity of pores other than organic pores in the target shale gas layer; A second determination module is used to determine a formation pore pressure coefficient of the target shale gas layer based on the corrected porosity of the target shale gas layer; A third determination module is used to determine the target shale gas layer as a shale gas layer to be developed when the formation pore pressure coefficient is greater than a reference value; The second determining module includes: A second determining unit is used to determine the formation effective stress of the target shale gas layer according to a second conversion formula based on the corrected porosity of the target shale gas layer; The second conversion formula: Among them, in the second conversion formula, refers to the formation effective stress of the target shale gas layer; refers to the modified porosity of the target shale gas formation; refers to the second parameter; refers to the third parameter; A conversion unit, used for converting the formation effective stress of the target shale gas layer to obtain the formation pore pressure coefficient of the target shale gas layer; The second determining unit is configured to: Obtaining sampling depths of a plurality of core samples, wherein the plurality of core samples are obtained by sampling shale gas layers at different depths, and the sampling depths of the plurality of core samples are all different; Determine the overburden pressure of each core sample based on the sampling depths of the multiple core samples to obtain multiple overburden pressures; Selecting multiple effective stresses ranging from zero pressure to half the maximum overburden pressure; Acquire multiple porosities corresponding to each core sample based on the multiple effective stresses; Normalizing the porosities of the multiple core samples, and performing mean processing on the multiple normalized porosities of each core sample to obtain multiple average porosities corresponding to the multiple effective stresses; The second conversion formula is obtained by performing exponential curve fitting on the multiple effective stresses and the multiple average porosities.

7. A computer-readable storage medium, characterized in that: The storage medium stores a computer program, and when the computer program is executed by a processor, the method according to any one of claims 1 to 5 is implemented.

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