A method, device and computer equipment for calculating paleo-pressure of a clastic rock gas reservoir

Abstract

The application provides a clastic rock gas reservoir paleo-pressure calculation method. Through analysis of test data of overburden porosity and formation compaction coefficient of sandstone samples in a test area, in combination with definitions of rock formation compaction coefficient and effective pore volume compression coefficient, a formula for characterizing pore volume change in a geological history period is established. The effective pore volume compression coefficient is calculated through measured data and a rock physical model, and then the change of the pore volume in each history period is obtained. When the reservoir is a dry gas or wet gas reservoir, the measured pressure and temperature of the present reservoir are taken as a starting point, in combination with a simulated formation thermal evolution history paleo-temperature curve, and then the reservoir paleo-pressure value in each history period is calculated. To some extent, the problem that the previous calculation method relies on microfluid inclusion observation and test and is difficult to continuously calculate the paleo-pressure in each history period is solved, which plays an important role in basin analysis and oil and gas accumulation dynamics research, and has important industrial application value in oil and gas exploration and evaluation.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of geological exploration, and in particular to a method and device for calculating paleo-pressure of a clastic rock gas reservoir and a computer device. BACKGROUND

[0002] Paleo-pressure recovery of a sedimentary basin is an important part of basin analysis and reservoir forming dynamics research, and plays an important role in oil and gas geological research and exploration. The research of paleo-pressure recovery is to calculate the pore pressure or pore pressure coefficient of the reservoir in each geological period during the uplift process according to the existing geological data, analysis and test data, and the sedimentary burial history.

[0003] There are many methods for recovering paleo-pressure, which can be roughly divided into the following categories: (1) using fluid inclusions to recover the paleo-pressure of the stratum, using the equilibrium relationship between the homogenization temperature and fluid composition of the hydrocarbon inclusions and the brine inclusions to obtain the paleo-pressure when the fluid is captured, common methods include calculating the paleo-pressure of the oil inclusions by PVT-sim software and calculating the paleo-pressure by methane inclusion laser Raman shift, etc. These methods require a large number of hydrocarbon inclusions that can be observed and measured under a microscope, and are not suitable for reservoirs with few or small inclusions; (2) using mudstone acoustic travel time data, based on the principle of irreversible compaction of mudstone, the paleo-pressure at the maximum burial depth of the stratum can be derived, common methods include the equivalent depth method and Fillippone formula method, etc. These methods can only estimate the pore pressure of the stratum except at the maximum burial depth; (3) using PetroMod, BasinMod and other basin simulation software to recover the paleo-pressure characteristics of single wells, profiles and planes, this method is based on the backstripping model, and a large amount of geological evolution data in the geological period is required to obtain reasonable calculation results, but these data are difficult to obtain and require a lot of debugging and testing; (4) for carbonate rock strata that lack oil inclusions and gas-bearing brine inclusions, calcite twins can be used as paleo-pressure gauges, combined with fracture analysis, joint roughness and rock mechanics parameters, the evolution of paleo-fluid pressure can be recovered by differential paleo-stress method, this method can only qualitatively analyze whether there is paleo-overpressure, and cannot quantitatively calculate the paleo-pressure value of each historical period; (5) other methods include using mineral veins to estimate paleo-pressure, estimating the formation pressure of clay minerals according to the formation temperature of clay minerals and the actual curve, and using tectonic stress method to study the paleo-pressure of the stratum under tectonic compression, etc. These methods are only qualitative estimates of the paleo-pressure under certain assumptions.

[0004] In summary, most of the current reservoir paleo-pressure calculation methods have limitations and are only suitable for qualitative estimation or only for specific regions. The current reliable quantitative calculation methods, such as the methane inclusion laser Raman shift calculation of paleo-pressure, need to rely on a large number of microscopic fluid inclusion observation and testing, but can only calculate the reservoir paleo-pressure value at the history time when the inclusion is filled. The paleo-pressure of other historical periods is based on the fitting and calculation of the test points, and there is currently a lack of a quantitative calculation method for the continuous paleo-pressure of the clastic rock gas reservoir which is suitable and considers the historical time evolution. SUMMARY

[0005] The present application aims to solve the technical problems of poor general applicability and difficulty in quantitative calculation of continuous paleo-pressure of the clastic rock gas reservoir.

[0006] According to a first aspect of the present application, the present application provides a clastic rock gas reservoir paleo-pressure calculation method, comprising the following steps:

[0007] obtaining a rock sample of a clastic rock formation to be calculated;

[0008] establishing a functional relationship between the rock effective pore volume compressibility coefficient, the rock matrix compressibility coefficient, the confining pressure and the pore volume of the rock sample;

[0009] obtaining the rock effective pore volume compressibility coefficient, the rock matrix compressibility coefficient and the confining pressure at any geological history time, and calculating the paleo-pore volume at any geological history time according to the functional relationship;

[0010] calculating the reservoir paleo-pressure at any geological history time according to the measured formation pressure, temperature and pore volume of the present reservoir, and the paleo-pore volume and paleo-geotemperature at any geological history time.

[0011] Further, the step of establishing a functional relationship between the rock effective pore volume compressibility coefficient, the rock matrix compressibility coefficient, the confining pressure and the pore volume of the rock sample comprises:

[0012] obtaining a functional relationship between the rock formation compaction coefficient, the pore volume, the pore volume change and the confining pressure change, which is a first expression:

[0013]

[0014] In the formula, C pc is the rock formation compaction coefficient, P -1 ; ΔP c is the change amount of the confining pressure; V p is the pore volume; ΔV p is the pore volume change amount;

[0015] The functional relationship between the rock formation compaction coefficient, the effective pore volume compressibility coefficient, and the matrix compressibility coefficient is obtained as the second expression:

[0016] C pc =C pp +C s

[0017] In the formula, C pp P is the effective pore volume compressibility coefficient of rock under constant confining pressure. -1 C s P is the rock matrix compressibility coefficient. -1 ;

[0018] Based on the first and second expressions, a functional relationship is established between the effective pore volume compressibility coefficient of rock, the rock matrix compressibility coefficient, the change in confining pressure, pore volume, and the change in pore volume, which is the third expression:

[0019]

[0020] Integrating both sides of the third expression yields the functional relationship between the effective pore volume compressibility coefficient of the rock, the matrix compressibility coefficient of the rock, the confining pressure, and the pore volume, which is the fourth expression:

[0021]

[0022] In the formula, e is the base of the natural logarithm, a priori value; a is the integration constant, C pp P is the effective pore volume compressibility coefficient of rock under constant confining pressure. -1 C s P is the rock matrix compressibility coefficient. -1 C s It is only related to the mineral composition of rocks, P c For confining pressure.

[0023] Furthermore, the step of establishing the functional relationship between the effective pore volume compressibility coefficient, the matrix compressibility coefficient, the confining pressure, and the pore volume of the rock sample further includes:

[0024] The method for obtaining the integration constant 'a' is as follows:

[0025] Using arbitrary test confining pressure P c1 The effective pore volume compressibility coefficient C of rocks under certain conditions pp1 and pore volume V p1 Substituting the discrete values ​​into the fourth expression, we get:

[0026] a=(C pp1 +C s )·P c1+ ln V p1 .

[0027] Further, the step of establishing the functional relationship between the rock effective pore volume compressibility, the rock matrix compressibility, the confining pressure and the pore volume of the rock sample further comprises:

[0028] Converting the rock effective pore volume compressibility, the rock matrix compressibility, the confining pressure and the pore volume in the fourth expression into values at any geologic time, i.e. obtaining the paleo-pore volume V pt at any geologic time, is a fifth expression:

[0029]

[0030] wherein e is the base of natural logarithm, a priori value; a is an integral constant; V pt is the pore volume at any geologic time t; C ppt is the rock effective pore volume compressibility at any geologic time t; P ct is the confining pressure at any geologic time t; C st is the matrix compressibility at any geologic time t; assuming that only mechanical deformation without mineral chemical reaction occurs during the formation uplift process, the mineral composition does not change, then C st = C s .

[0031] Preferably, the step of obtaining the rock effective pore volume compressibility at any geologic time comprises:

[0032] According to the functional relationship between any geologic time t and the formation depth H t , the formation depth at any geologic time is calculated as:

[0033] H t = f(t)

[0034] According to the depth and porosity relationship exponential model, the porosity φ t at any geologic time t is calculated as:

[0035]

[0036] wherein φ0 is the porosity under present normal pressure, a priori value; e is the base of natural logarithm, a priori value; k is the compaction factor, a priori value; H t is the formation depth at any geologic time t; H0 is the present formation depth, a priori value;

[0037] According to the effective pore volume compressibility C ppAn empirical relationship formula between porosity φ and effective pore volume compressibility C

[0038]

[0039] The effective pore volume compressibility C pp in the empirical relationship formula is converted into the value at any geologic time t, i.e. the effective pore volume compressibility C ppt of the rock at any geologic time is obtained.

[0040]

[0041] In the formula, φ t is the porosity at any geologic time t.

[0042] Preferably, the step of obtaining the rock matrix compressibility at any geologic time comprises:

[0043] Obtaining the volume percentage f i of each mineral in the rock sample under normal pressure;

[0044] According to the volume percentage f i of each mineral in the rock sample, the rock matrix compressibility C s of the rock sample is calculated using the Voigt-Reuss-Hill average modulus model:

[0045]

[0046] In the formula, C i is the compressibility of the N mineral components in the rock sample, and i is an integer greater than or equal to 1.

[0047] Preferably, the calculation formula of the confining pressure at any geologic time is as follows:

[0048] P ct = P c0 + ρ s (H t -H0)

[0049] In the formula, P ct is the confining pressure at any geologic time t, P c0 is the present formation confining pressure, which is a priori value; ρ s is the empirical value of the shallow formation density, which is a priori value; H t is the formation depth at any geologic time t; and H0 is the present formation depth, which is a priori value.

[0050] Further, in the step of calculating the reservoir paleo-pressure at any geologic history time according to the measured formation pressure, temperature and pore volume of the present reservoir, and the paleo-pore volume and paleo-geothermal temperature at any geologic history time, the calculation formula of the reservoir paleo-pressure at any geologic history time is as follows:

[0051]

[0052] wherein, P p0 , T0 and V p0 are the measured formation pressure, temperature and pore volume of the present reservoir, which are priori values; T t is the paleo-geothermal temperature at any geologic history time t; V pt is the pore volume at any geologic history time t, and P pt is the reservoir paleo-pressure at any geologic history time t.

[0053] According to the second aspect of the present application, the present application provides a device for calculating reservoir paleo-pressure of clastic rock gas reservoir, comprising the following modules:

[0054] a sample obtaining module for obtaining a rock sample of the clastic rock formation to be calculated;

[0055] a function relationship establishing module for establishing a function relationship among the rock effective pore volume compressibility coefficient, rock matrix compressibility coefficient, confining pressure and pore volume of the rock sample;

[0056] a paleo-pore volume calculating module for obtaining the rock effective pore volume compressibility coefficient, rock matrix compressibility coefficient and confining pressure at any geologic history time, and calculating the paleo-pore volume at any geologic history time according to the function relationship;

[0057] a reservoir paleo-pressure calculating module for calculating the reservoir paleo-pressure at any geologic history time according to the measured formation pressure, temperature and pore volume of the present reservoir, and the paleo-pore volume and paleo-geothermal temperature at any geologic history time.

[0058] According to the third aspect of the present application, the present application provides a computer device comprising a memory and a processor, wherein the memory stores a computer program, and the computer program is executed by the processor to perform the clastic rock gas reservoir paleo-pressure calculating method.

[0059] The technical solution provided by the present application has the following beneficial effects:

[0060] Aiming at the difficulty problem of the current gas reservoir generally applicable and continuous paleo-pressure quantitative calculation, the effective pore volume compression coefficient of rock elastic parameter is taken as the key parameter of the model, and the quantitative relationship between the pore volume change of rock in each historical period and the effective pore volume compression coefficient and the overburden load is theoretically established. Then, the paleo-pressure value of each historical period is calculated by combining the ideal gas state equation. This is a new method for calculating the paleo-pressure of the formation. The test parameters required in the calculation process, such as normal pressure porosity and full rock mineral XRD data, have low acquisition cost, and the paleo-pressure value of each historical period can be calculated continuously, which solves the problem that the previous paleo-pressure quantitative calculation method relies on microfluid inclusion observation and test, and it is difficult to calculate the paleo-pressure of each geological period continuously. It plays an important role in basin analysis and oil and gas accumulation dynamics research, and has important industrial application value in oil and gas exploration and evaluation. BRIEF DESCRIPTION OF DRAWINGS

[0061] The specific effects of the present application will be further described below in combination with the drawings and examples. In the drawings:

[0062] Figure 1 is a flow chart of the clastic rock gas reservoir paleo-pressure calculation method based on the effective pore volume compression coefficient of the embodiment of the present application;

[0063] Figure 2 is a 3500m burial depth-geological time evolution diagram of a certain well of a tight clastic rock gas reservoir in a intracratonic sedimentary basin of the embodiment of the present application;

[0064] Figure 3 is a 3500m temperature-geological time evolution diagram of a certain well of a tight clastic rock gas reservoir in a intracratonic sedimentary basin of the embodiment of the present application;

[0065] Figure 4 is a paleo-pressure-geological age relationship diagram of a certain well of a tight clastic rock gas reservoir in a intracratonic sedimentary basin of the embodiment of the present application;

[0066] Figure 5 is a structure diagram of the clastic rock gas reservoir paleo-pressure calculation device based on the effective pore volume compression coefficient of the embodiment of the present application. DETAILED DESCRIPTION

[0067] In order to have a clearer understanding of the technical features, objects and effects of the present application, the specific embodiments of the present application will be described in detail with reference to the drawings.

[0068] Example one:

[0069] Reference Figure 1 The present embodiment provides a clastic rock gas reservoir paleo-pressure calculation method based on the effective pore volume compression coefficient, which comprises the following steps:

[0070] S1: obtaining a rock sample of the clastic rock formation to be calculated;

[0071] S1 specifically comprises: obtaining a rock sample of the clastic rock formation to be calculated, selecting a sample (No. YP02) with a methane inclusion laser Raman shift recovered paleo-pressure value, testing the pore volume V p , porosity φ0(Table 1) and whole rock XRD test data to obtain the volume percentage f i of each mineral (Table 2), providing a data basis for subsequent calculation of the paleo-pressure of the reservoir.

[0072] Table 1 Experimental sample information and porosity test data of a well in a clathrate sedimentary basin dense clastic rock gas reservoir

[0073]

[0074] Table 2 Whole rock XRD test mineral content data of a sample of a well in a clathrate sedimentary basin dense clastic rock gas reservoir

[0075]

[0076] S2: establishing a functional relationship between the rock effective pore volume compressibility coefficient of the rock sample, the rock matrix compressibility coefficient, the confining pressure and the pore volume;

[0077] S2 specifically comprises:

[0078] S21: obtaining a functional relationship between the rock formation compaction coefficient and the pore volume, the pore volume change, and the confining pressure change, for a first expression:

[0079]

[0080] In the formula, C pc is the rock formation compaction coefficient, P -1 ; ΔP c is the change amount of the confining pressure; V p is the pore volume; ΔV p is the pore volume change amount;

[0081] S22: obtaining a functional relationship between the rock formation compaction coefficient and the rock effective pore volume compressibility coefficient, the rock matrix compressibility coefficient, for a second expression:

[0082] C pc =C pp +C s

[0083] In the formula, C pp is the rock effective pore volume compressibility coefficient when the confining pressure is constant, P -1 ; C s is the rock matrix compressibility coefficient, P-1 ;

[0084] S23: According to the first expression and the second expression, a function relationship between the effective pore volume compressibility of rock, the matrix compressibility of rock, the confining pressure change, the pore volume and the pore volume change is established, which is a third expression:

[0085]

[0086] S24: The third expression is integrated on both sides to obtain a function relationship between the effective pore volume compressibility of rock, the matrix compressibility of rock, the confining pressure and the pore volume, which is a fourth expression:

[0087]

[0088] In the formula, e is the base number of natural logarithm, a priori value; a is an integral constant, C pp is the effective pore volume compressibility of rock when the confining pressure is constant, P -1 ; C s is the matrix compressibility of rock, P -1 , C s is only related to the composition of rock mineral composition, P c is the confining pressure;

[0089] S25: The effective pore volume compressibility of rock, the matrix compressibility of rock, the confining pressure and the pore volume in the fourth expression are converted into values at any geologic history time, that is, a calculation formula of the paleo-pore volume V pt at any geologic history time is obtained, which is a fifth expression:

[0090]

[0091] In the formula, e is the base number of natural logarithm, a priori value; a is an integral constant; V pt is the pore volume at any geologic history time t; C ppt is the effective pore volume compressibility of rock at any geologic history time t; P ct is the confining pressure at any geologic history time t; C st is the matrix compressibility at any geologic history time t; it is assumed that only mechanical deformation action without mineral chemical reaction occurs in the process of stratum uplift, and the mineral composition does not change, so C st =C s .

[0092] Optionally, in step S2, further comprising:

[0093] An integral constant a is obtained; in this embodiment, the method for obtaining the integral constant a is:

[0094] Using arbitrary test confining pressure P c1 The effective pore volume compressibility coefficient C of rocks under certain conditions pp1 and pore volume V p1 Substituting the discrete values ​​into the fourth expression, we obtain:

[0095] a=(C pp1 +C s )·P c1 +ln V p1

[0096] S3: Obtain the effective pore volume compressibility coefficient, matrix compressibility coefficient, and confining pressure of rocks at any geological time, and calculate the paleopore volume at any geological time based on the aforementioned functional relationship;

[0097] S3 specifically includes:

[0098] S31: Obtain the effective pore volume compressibility coefficient of rocks at any geological time.

[0099] S31 further includes:

[0100] S311: Any geological time t and stratigraphic depth H t The functional relationship can be based on the basin simulation burial history map ( Figure 2 For example, sample YP02 is currently buried at a depth of 3500m. At t=100Ma, the burial depth H is... t The depth is 4200m. Based on any geological historical time t and stratigraphic depth H... t The functional relationship is used to calculate the stratigraphic depth at any geological time:

[0101] H t =f(t)

[0102] S312: Based on the depth-porosity relationship index model, the porosity φ at any geological time t is calculated. t :

[0103]

[0104] In the formula, φ0 is the porosity under normal pressure, an a priori value; e is the base of the natural logarithm, an a priori value; k is the compaction factor, an a priori value; H t H is the stratigraphic depth at any geological time t; H0 is the current stratigraphic depth, a priori value.

[0105] S313: The effective pore volume compressibility coefficient C was obtained by applying the experimental statistical results of Hall (1953). pp An empirical formula relating porosity φ to porosity is used to calculate the effective pore volume compressibility coefficient.

[0106]

[0107] S314: obtaining the effective pore volume compressibility coefficient C pp of the rock at any geologic history time t, i.e. obtaining the effective pore volume compressibility coefficient C ppt of the rock at any geologic history time t:

[0108]

[0109] wherein φ t is the porosity at any geologic history time t;

[0110] S32: obtaining the matrix compressibility coefficient of the rock at any geologic history time;

[0111] S32 further comprises:

[0112] S321: obtaining the volume percentage f i of each mineral in the rock sample under normal pressure;

[0113] S322: according to the volume percentage f i of each mineral in the rock sample, calculating the matrix compressibility coefficient C s of the rock sample using the Voigt-Reuss-Hill average modulus model:

[0114]

[0115] wherein C i is the compressibility coefficient of N mineral components in the rock sample, the empirical value of the compressibility coefficient of the mineral components in the rock sample is shown in Table 3, which is a priori value, and i is an integer greater than or equal to 1.

[0116] Table 3: empirical value of compressibility coefficient of each mineral component

[0117]

[0118] S33: obtaining the confining pressure at any geologic history time, and the specific calculation formula is as follows:

[0119] P ct = P c0 + p s (H t -H0)

[0120] wherein P ct is the confining pressure at any geologic history time t, P c0 is the present formation confining pressure, which is a priori value; p sThe density of shallow strata is an empirical value, a priori, and is taken as 2.65 g / cm³. 3 H t H is the stratum depth at any geological time t; H0 is the current stratum depth, a priori value.

[0121] S34: Substitute the results obtained from steps S31-S33 into the function relationship established in S2 to calculate the paleopore volume for any geological historical time.

[0122] S4: Based on the current measured formation pressure, temperature and pore volume of the reservoir, as well as the paleopore volume and paleotemperature of any geological history time, the paleopressure of the reservoir at any geological history time is calculated.

[0123] The specific calculation formula for S4 is as follows:

[0124]

[0125] In the formula, P p0 T0 and V p0 These represent the current measured formation pressure, temperature, and pore volume of the reservoir, which are a priori values; T t V represents the paleotemperature at any geological time t; pt Let P be the pore volume at any geological time t. pt Let t be the reservoir paleopressure at any geological time t.

[0126] Optionally, the formation temperature T at any geological history time t in step S4 formula... t Temperature-geological time evolution diagrams can be simulated from the basin's thermal history. Figure 3 )get:

[0127] T t =f(t)

[0128] The results obtained by using the method described in the embodiments of the present invention are as follows: Figure 4 As shown, the paleopressure values ​​(the lines in Figure 4) and the paleopressure values ​​recovered by laser Raman shift analysis of methane inclusions ( Figure 4 The data points in the data are highly consistent, and this method can accurately calculate the paleopressure value of gas reservoirs. It has stronger applicability and practicality than previous methods, and can continuously calculate the paleopressure value of each historical period, which has certain industrial application value.

[0129] The present application establishes a theoretical formula for characterizing the change of pore volume in the geological history period by analyzing the test data of the overburden porosity and the formation compaction coefficient of the sandstone sample in the test area, combining the definition of the rock formation compaction coefficient and the effective pore volume compression coefficient, and calculating the effective pore volume compression coefficient through the experimental test data and the rock physical model, and then obtaining the change of the pore volume in each historical period. When the reservoir is a dry gas or wet gas reservoir (the temperature of the gas reservoir is always higher than the phase envelope region, and there is no phase change process), based on the ideal gas state equation, taking the measured pressure and temperature of the present reservoir as the starting point, combining the ancient temperature curve of the simulated formation thermal evolution history, and then calculating the reservoir paleopressure value in each historical period.

[0130] The present embodiment provides a reservoir gas reservoir paleopressure calculation method based on the effective pore volume compression coefficient. To some extent, the problem that the previous paleopressure quantitative calculation method relies on microscopic fluid inclusion observation and test and is difficult to continuously calculate the paleopressure in each geological history period is solved. By comparing the calculated paleopressure value with the methane inclusion laser Raman shift recovered paleopressure value, it can be known that this method can accurately calculate the reservoir paleopressure value of the gas reservoir, has stronger applicability and practicality than the previous method, and can continuously calculate the paleopressure value in each historical period, and has certain industrial application value.

[0131] Embodiment two:

[0132] Reference Figure 5 The present embodiment provides a clastic rock gas reservoir reservoir paleopressure calculation device based on the effective pore volume compression coefficient, comprising the following modules:

[0133] The sample to be measured acquisition module 1 is used to acquire the rock sample of the clastic rock formation to be calculated;

[0134] The function relationship establishment module 2 is used to establish the function relationship among the rock effective pore volume compression coefficient, the rock matrix compression coefficient, the confining pressure and the pore volume of the rock sample;

[0135] The paleopore volume calculation module 3 is used to acquire the rock effective pore volume compression coefficient, the rock matrix compression coefficient and the confining pressure at any geological history time, and calculate the paleopore volume at any geological history time according to the function relationship;

[0136] The reservoir paleopressure calculation module 4 is used to calculate the reservoir paleopressure at any geological history time according to the measured formation pressure, temperature and pore volume of the present reservoir, and the paleopore volume and paleogeotemperature at any historical time.

[0137] Embodiment three:

[0138] The embodiment provides a computer device, which comprises a memory and a processor, the memory stores a computer program, the computer program is executed by the processor, each process of the method for calculating the paleo-pressure of a clastic rock gas reservoir is executed, and the same technical effects can be achieved.

[0139] It should be noted that, in this document, the terms "comprising", "including", or any other variant thereof are intended to cover a non-exclusive inclusion, so that a process, method, article, or system that includes a list of elements not only includes those elements, but also includes other elements not expressly listed, or inherent to such a process, method, article, or system. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of additional identical elements in the process, method, article, or system that includes the element.

[0140] The above-mentioned serial numbers of the embodiments of the application are only for description, and do not represent the advantages and disadvantages of the embodiments. In the unit claims in which several devices are listed, several of the devices can be embodied by the same hardware item. The use of the words first, second, and third does not represent any order, and the words can be interpreted as identifiers.

[0141] The above is only the preferred embodiment of the application, and does not limit the patent scope of the application, and any equivalent structure or equivalent process transformation using the content of the specification and the drawings, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the application.

Claims

1. A method for calculating paleo-pressures in a clastic gas reservoir, characterized in that, The method comprises the following steps: obtaining a rock sample of a clastic rock formation to be calculated; establishing a functional relationship among the rock effective pore volume compressibility coefficient, the rock matrix compressibility coefficient, the confining pressure and the pore volume of the rock sample, comprising: obtaining a functional relationship among the rock formation compaction coefficient, the pore volume, the pore volume change and the confining pressure change, which is a first expression: In the formula, C pc P is the compaction coefficient of the rock formation. -1 ;ΔP c V is the change in confining pressure. p ΔV represents the pore volume. p This represents the change in pore volume. obtaining a functional relationship among the rock formation compaction coefficient, the rock effective pore volume compressibility coefficient and the rock matrix compressibility coefficient, which is a second expression: C pc = C pp + C s where C pp is the effective pore volume compressibility of the rock for constant confining pressure, P -1 ; C s is the matrix compressibility of the rock, P -1 ; according to the first expression and the second expression, establishing a functional relationship among the rock effective pore volume compressibility coefficient, the rock matrix compressibility coefficient, the confining pressure change, the pore volume and the pore volume change, which is a third expression: integrating both sides of the third expression to obtain a functional relationship among the rock effective pore volume compressibility coefficient, the rock matrix compressibility coefficient, the confining pressure and the pore volume, which is a fourth expression: where e is the natural logarithm base, a priori value; a is the integration constant, C pp is the effective pore volume compressibility of rock at constant confining pressure, P -1 ; C s is the matrix compressibility of rock, P -1 , C s is only related to the mineral composition of rock, P c is the confining pressure; obtaining the rock effective pore volume compressibility coefficient, the rock matrix compressibility coefficient and the confining pressure at any geologic history time, and calculating the paleo-pore volume at any geologic history time according to the functional relationship; calculating the reservoir paleo-pressure at any geologic history time according to the measured formation pressure, temperature and pore volume of the present reservoir, and the paleo-pore volume and paleo-geothermal temperature at any geologic history time.

2. The method of calculating paleo-pressures in a clastic gas reservoir according to claim 1, wherein, The step of establishing a functional relationship among the rock effective pore volume compressibility coefficient, the rock matrix compressibility coefficient, the confining pressure and the pore volume of the rock sample further comprises: obtaining an integral constant a; the method for obtaining the integral constant a is: The discrete values of the effective pore volume compressibility C pp1 and of the pore volume V p1 under the condition of an arbitrary test confining pressure P c1 are inserted into the fourth expression, obtaining: a = (C pp1 + C s ) · P c1 + ln V p1 .

3. The method of calculating paleo-pressures in a clastic gas reservoir according to claim 1, wherein, The step of establishing a functional relationship among the rock effective pore volume compressibility coefficient, the rock matrix compressibility coefficient, the confining pressure and the pore volume of the rock sample further comprises: The rock effective pore volume compressibility in the fourth expression, the rock matrix compressibility, the confining pressure, and the pore volume are converted to values at any geologic history time, i.e., the paleo-pore volume Vpaleoat any geologic history time is obtained pt The calculation formula is the fifth expression: where e is the natural logarithm base, a priori value; a is the integration constant; V pt is the pore volume at any geologic time t; C ppt is the effective pore volume compressibility of the rock at any geologic time t; P ct is the confining pressure at any geologic time t; C st is the matrix compressibility at any geologic time t; assuming that only mechanical deformation occurs during the process of the formation uplift without mineral chemical reaction, the mineral composition does not change, then C st = C s .

4. The method of calculating paleo-pressures in a clastic gas reservoir of claim 1, wherein, The step of obtaining the rock effective pore volume compressibility coefficient at any geologic history time comprises: According to the function relationship of any geologic history time t and the stratum depth H t , the stratum depth of any geologic history time is calculated: H t = f(t) According to the depth and porosity relationship index model, the porosity φ at any geologic history time t is calculated t : where φ0is the present-day porosity at atmospheric pressure, a prior; e is the base of the natural logarithm, a prior; k is the compaction factor, a prior; H t is the depth of the formation at any geologic time t; H0is the present-day depth of the formation, a prior According to the effective pore volume compressibility coefficient C pp The empirical relationship formula between porosity φ and the effective pore volume compressibility coefficient C is calculated: The effective pore volume compressibility C in the empirical relationship formula is substituted by the effective pore volume compressibility C pp The value of the effective pore volume compressibility C at any geologic history time t is obtained by converting the porosity φ at any geologic history time t, i.e. ppt The calculation formula of the effective pore volume compressibility C where φ is the porosity at any geohistorical time t. t is the porosity at any geohistorical time t.

5. The method of calculating paleo-pressures in a clastic gas reservoir of claim 1, wherein, The step of obtaining the rock matrix compressibility coefficient at any geologic history time comprises: Obtaining the volume percentage f of each mineral of the rock sample at normal pressure i ; According to the volume percentage f of each mineral constituting the rock sample i , the rock matrix compressibility coefficient C of the rock sample is calculated using the Voigt-Reuss-Hill average modulus model s : In the formula, C i is the compressibility of the i-th mineral component in the rock sample, and i is an integer greater than or equal to 1.

6. The method of calculating paleo-pressures in a clastic gas reservoir of claim 1, wherein, The calculation formula of the confining pressure at any geologic history time is as follows: P ct = P c0 + p s (H t - H0) where P ct is the confining pressure at any geologic time t, P c0 is the present-day formation confining pressure, a priori; p s is the empirical value of the shallow formation density, a priori; H t is the formation depth at any geologic time t; H0is the present-day formation depth, a priori.

7. The method of calculating paleo-pressures in a clastic gas reservoir of claim 1, wherein, In the step of calculating the reservoir paleo-pressure at any geologic history time according to the measured formation pressure, temperature and pore volume of the present reservoir, and the paleo-pore volume and paleo-geothermal temperature at any geologic history time, the calculation formula of the reservoir paleo-pressure at any geologic history time is as follows: where P p0 , T0and V p0 are the present reservoir measured formation pressure, temperature and pore volume, respectively, T t is the geotemperature at any geologic time t, V pt is the pore volume at any geologic time t, and P pt is the reservoir paleo-pressure at any geologic time t.

8. A device for calculating paleo-pressures of a clastic gas reservoir, characterized in that, The method comprises the following modules: a sample obtaining module for obtaining a rock sample of a clastic rock formation to be calculated; a functional relationship establishing module for establishing a functional relationship among the rock effective pore volume compressibility coefficient, the rock matrix compressibility coefficient, the confining pressure and the pore volume of the rock sample, comprising: obtaining a functional relationship among the rock formation compaction coefficient, the pore volume, the pore volume change and the confining pressure change, which is a first expression: In the formula, C pc is a rock formation compaction coefficient, P -1 ; ΔP c is a change in confining pressure; V p is a pore volume; ΔV p is a pore volume change amount; obtaining a functional relationship among the rock formation compaction coefficient, the rock effective pore volume compressibility coefficient and the rock matrix compressibility coefficient, which is a second expression: C pc = C pp + C s where C pp is the effective pore volume compressibility of the rock for constant confining pressure, P -1 ; C s is the matrix compressibility of the rock, P -1 ; according to the first expression and the second expression, establishing a functional relationship among the rock effective pore volume compressibility coefficient, the rock matrix compressibility coefficient, the confining pressure change, the pore volume and the pore volume change, which is a third expression: Integrating both sides of the third expression, a function relationship between the rock effective pore volume compressibility, the rock matrix compressibility, the confining pressure and the pore volume is obtained, which is a fourth expression: where e is the natural logarithm base, a priori value; a is the integration constant, C pp is the effective pore volume compressibility of the rock for constant confining pressure, P -1 ; C s is the matrix compressibility of the rock, P -1 , C s is only related to the mineral composition of the rock, P c is the confining pressure; The paleo-pore volume calculation module is configured to obtain the rock effective pore volume compressibility, the rock matrix compressibility and the confining pressure at any geologic history time, and calculate the paleo-pore volume at any geologic history time according to the function relationship. The reservoir paleo-pressure calculation module is configured to calculate the reservoir paleo-pressure at any geologic history time according to the measured formation pressure, temperature and pore volume of the present reservoir, and the paleo-pore volume and paleo-geothermal temperature at any geologic history time.

9. A computer device, comprising: The computer device comprises a memory and a processor, and the memory stores a computer program which, when executed by the processor, performs the clastic rock gas reservoir paleo-pressure calculation method according to any one of claims 1-7.

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