A method, device and computer equipment for calculating paleopressure of clastic rock reservoir

Abstract

The present invention provides a method for calculating the paleopressure of clastic reservoirs. By analyzing the test data of porosity and formation compaction coefficient, combined with the definition of formation compaction coefficient, a theoretical formula is established to characterize the change of formation compaction coefficient with depth during the period of tectonic uplift; the coexistence of multiphase fluids under formation conditions is fully considered, and the theoretical equation for the change of pore fluid volume in closed formations before and after tectonic uplift is derived to solve the calculation formula of reservoir paleopressure. Taking the current measured pressure and temperature of the reservoir as the starting point, combined with the paleotemperature curve of the simulated formation thermal evolution history, the reservoir paleopressure value of the entire tectonic uplift period is calculated. To a certain extent, it solves the problem that the previous quantitative calculation method of paleopressure relies on the observation and testing of microscopic fluid inclusions and is difficult to continuously calculate the paleopressure of each geological historical period. It plays an important role in basin analysis and oil and gas reservoir dynamics research, and has important industrial application value in oil and gas exploration and evaluation.

Description

Technical Field

[0001] The present invention relates to the field of geological exploration, and in particular to a method, a device and a computer equipment for calculating the paleopressure of a clastic rock reservoir. Background Art

[0002] The restoration of paleo-pressure in sedimentary basin reservoirs is an important part of basin analysis and reservoir formation dynamics research, and plays an important role in oil and gas geological research and exploration. The research on the restoration of paleo-pressure is to calculate the formation pore pressure or pore pressure coefficient of each geological historical period during the uplift process of the reservoir based on the existing geological data, analytical test data and the history of formation sedimentation and burial.

[0003] A variety of methods for restoring paleopressure have been developed, which can be roughly divided into the following categories: (1) Using fluid inclusions to restore reservoir paleopressure, the paleopressure at the time of fluid capture is obtained by using the equilibrium relationship between the homogenized temperature and fluid composition of hydrocarbon inclusions and brine inclusions of the same period. Common methods include: calculating the capture pressure of oil inclusions using PVT-sim software and calculating the capture pressure of gas inclusions using the laser Raman shift method. These methods often restore the paleopressure of a single geological period and a single phase, not the paleopressure of reservoirs in continuous geological periods and mixed phases. They are also not applicable to reservoirs with few or small inclusions and no captured inclusions during the tectonic uplift period. (2) Using mudstone acoustic time difference data, based on the principle of irreversible mudstone compaction, the paleopressure at the maximum burial depth of the mudstone formation can be derived. Common methods include the equivalent depth method. These methods can only estimate the formation pore pressure at the maximum burial depth. (3) Using PetroMod , BasinMod and other basin simulation software to restore the paleopressure characteristics of single wells, profiles and planes. This method is based on the backstripping model. In order to obtain reasonable calculation results, a large amount of evolution data from geological history is often required. However, these data are difficult to obtain and require a lot of debugging and testing. (4) For carbonate rock formations that lack oil inclusions and gaseous hydrocarbon inclusions, calcite twins can be used as paleopressure gauges. Combined with fracture analysis, suture roughness and rock mechanics parameters, the differential paleostress method can be used to restore the evolution of paleofluid pressure. This method can only qualitatively analyze whether there is paleo-overpressure, and cannot quantitatively calculate the paleopressure values ​​of reservoirs in different historical periods. (5) Other methods include estimating paleopressure using mineral veins, estimating the formation pressure of clay minerals based on the formation temperature and actual curves of clay minerals, and the tectonic stress method used to study the paleopressure of reservoirs under tectonic compression. These methods are all based on certain assumptions and can only qualitatively estimate the size of paleopressure.

[0004] In summary, most of the existing reservoir paleopressure calculation methods have limitations and are only applicable to qualitative estimation or specific areas. The more reliable quantitative calculation methods, such as the calculation of paleopressure using laser Raman shift of fluid inclusions, require a large number of microscopic fluid inclusion observations and tests, but can only calculate the reservoir paleopressure value at the historical moment of inclusion filling. The paleopressure of other historical periods is based on the fitting and estimation of test points. At present, there is still a lack of a paleopressure quantitative calculation method for clastic reservoirs that is suitable for multi-phase mixed accumulation and considers the continuity of historical time evolution. Summary of the invention

[0005] The main technical problem solved by the present invention is to provide a quantitative calculation method of paleopressure for clastic rock reservoirs, which is suitable for multi-phase mixed accumulation and takes into account the continuity of historical time evolution.

[0006] According to a first aspect of the present invention, the present invention provides a method for calculating paleopressure of a clastic reservoir, comprising the following steps:

[0007] Establish the rock formation compaction coefficient C at any geological history time pct , pore volume V pt , the change in pore volume ΔV p and the change in effective stress Δσ efft The functional relationship between is the first expression:

[0008]

[0009] Based on the formation sealing condition, the formation pore fluid volume V at any geological history time ft The current formation pore fluid volume V f0 The functional relationship between them is the second expression:

[0010] V f0 =V ft ·[1+α f (T0-T t )]·[1-β f (P p0 -P pt )]

[0011] The second expression satisfies V pt =V ft , ΔV p =ΔV f , ΔV f =V f0 -V ft ;

[0012] According to the first expression and the second expression, a functional relationship between the rock formation compaction coefficient, the change in effective stress, and the temperature and pressure of the formation pore fluid is established, which is a third expression;

[0013] C pct ·Δσ efft =β f (P p0 -P pt )-α f (T0-T t )+α f (T0-T t )·β f (P p0 -P pt )

[0014] According to the calculation expression of the change in effective stress and the third expression, a calculation formula for reservoir paleopressure at any geological time t is established, which is the fourth expression:

[0015]

[0016] In the formula, T0, P p0 and P r0 are the current measured reservoir formation temperature, pressure and overburden pressure, which are a priori values; T t , P pt , P rt , C pct and Δσ efft are the changes in formation temperature, formation pressure, overburden formation pressure, rock formation compaction coefficient and effective stress at any geological history time t; β f and α f are the pore fluid compressibility coefficient and pore fluid thermal expansion coefficient, V pt 、V ft are the pore volume and fluid volume at any geological time t, respectively; ΔV p , ΔV f are the pore volume increment and fluid volume increment respectively;

[0017] Obtain the rock formation compaction coefficient, overburden formation pressure and formation temperature at any geological history time, combine the current measured formation temperature, pressure and overburden formation pressure of the reservoir, and calculate the reservoir paleopressure according to the fourth expression.

[0018] The method further comprises the following steps:

[0019] Obtain the rock formation compaction coefficient C of clastic rock samples under different effective stresses pcA series of discrete values ​​of , through the data fitting method, the fitting relationship between effective stress and rock formation compaction coefficient is constructed as the first expression:

[0020]

[0021] A series of discrete values ​​of the rock porosity φ of the clastic rock samples under different effective stresses are obtained, and the power fitting method is used to construct the fitting relationship between effective stress and rock porosity, which is the sixth expression:

[0022] σ eff = bφ c

[0023] According to the fifth expression and the sixth expression, the relationship between the compaction coefficient of the rock formation and the porosity is obtained, which is the seventh expression:

[0024]

[0025] In the formula, C pc is the rock formation compaction coefficient, Pa -1 ; φ is porosity, %; a, b, c are discrete value fitting coefficients; the seventh expression is used to obtain the rock stratum compaction coefficient at any geological historical time.

[0026] Preferably, a PoroPDP-200 overburden porosity measuring instrument is used to test the compaction coefficient and porosity of the rock formation using a helium method.

[0027] Preferably, the thermal expansion coefficient of the pore fluid α f and the pore fluid compressibility coefficient β f They are calculated by the following formulas:

[0028] α f =(1-S w )·α fg +S w α fw

[0029]

[0030] In the formula, β fw , β fg are the compression coefficients of formation water and natural gas, respectively, which are a priori values; α fw , S w is the thermal expansion coefficient and water saturation of formation water, which are a priori values; m is the empirical coefficient, which is a priori value; α fg is the thermal expansion coefficient of natural gas.

[0031] Preferably, the calculation expression of the change in effective stress is:

[0032] Δσ efft =[(P rt -P pt )-(P r0 -P p0 )].

[0033] Preferably, the step of obtaining the rock formation compaction coefficient at any geological historical time includes:

[0034] According to any geological history time t and stratum depth H t The functional relationship of is used to calculate the stratigraphic depth at any geological time:

[0035] H t =f(t)

[0036] According to the current depth-sonic-measured porosity relationship index model, the porosity φ at any geological history time t is calculated. t :

[0037]

[0038] Where φ0 is the porosity at current normal pressure, a priori value; e is the base of the natural logarithm, a priori value; k is the compaction factor, a priori value; H t is the stratigraphic depth at any geological time t; H0 is the current stratigraphic depth, a priori value;

[0039] The rock formation compaction coefficient and porosity in the seventh expression are converted into values ​​at any geological historical time t, that is, the calculation formula of the rock formation compaction coefficient at any geological historical time is obtained:

[0040]

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

[0042] Preferably, the calculation formula for obtaining the overburden pressure at any geological historical time is as follows:

[0043] P rt =ρ s ·H t ·g

[0044] In the formula, ρ s is the empirical value of shallow stratum density, which is a priori value; H t is the depth of the stratum at any geological time t; g is the gravitational acceleration.

[0045] Preferably, the ground temperature at any geological historical time t is obtained by a specific method: obtaining it according to a basin thermal history simulation temperature-geological time evolution diagram.

[0046] According to a second aspect of the present invention, the present invention also provides a clastic reservoir paleopressure calculation device, comprising the following modules:

[0047] The first expression building module is used to establish the rock stratum compaction coefficient C at any geological history time. pct , pore volume V pt , the change in pore volume ΔV p and the change in effective stress Δσ efft The functional relationship between is the first expression:

[0048]

[0049] The second expression building module is used to obtain the formation pore fluid volume V at any geological history time under formation sealing conditions. ft The current formation pore fluid volume V f0 The functional relationship between them is the second expression:

[0050] V f0 =V ft ·[1+α f (T0-T t )]·[1-β f (P p0 -P pt )]

[0051] The second expression satisfies V pt =V ft , ΔV p =ΔV f , ΔV f =V f0 -V ft ;

[0052] A third expression building module is used to build a functional relationship between the rock formation compaction coefficient, the change in effective stress, and the temperature and pressure of the formation pore fluid according to the first expression and the second expression, which is a third expression;

[0053] C pct ·Δσ efft =β f (P p0 -P pt )-α f (T0-T t )+α f (T0-T t )·β f(P p0 -P pt )

[0054] The fourth expression establishment module is used to establish a reservoir paleopressure calculation formula at any geological time t according to the calculation expression of the change in effective stress and the third expression, which is the fourth expression:

[0055]

[0056] In the formula, T0, P p0 and P r0 are the current measured reservoir formation temperature, pressure and overburden pressure, which are a priori values; T t , P pt , P rt , C pct and Δσ efft are the changes in formation temperature, formation pressure, overburden formation pressure, rock formation compaction coefficient and effective stress at any geological history time t; β f and α f are the pore fluid compressibility coefficient and pore fluid thermal expansion coefficient, V pt 、V ft are the pore volume and fluid volume at any geological time t, respectively; ΔV p , ΔV f are the pore volume increment and fluid volume increment respectively;

[0057] The reservoir paleopressure calculation module is used to obtain the rock formation compaction coefficient, overburden formation pressure and formation temperature at any geological history time, and combine the current measured reservoir formation temperature, pressure and overburden formation pressure to calculate the reservoir paleopressure according to the fourth expression.

[0058] According to the third aspect of the present invention, the present invention also provides a computer device, which includes a memory and a processor, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the method for calculating the paleopressure of clastic reservoirs is executed.

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

[0060] Aiming at the difficult problem of quantitative calculation of paleopressure of reservoirs (oil, gas, water) that is generally applicable and continuous, the rock formation compaction coefficient, the compression coefficient of formation fluid and the thermal expansion coefficient are used as the key parameters of the model. The quantitative relationship between the pore volume change of rocks in various historical periods and the rock formation compaction coefficient and the overburden load is theoretically established; then the theoretical equation of the change of pore fluid volume before and after formation uplift is constructed to solve the reservoir paleopressure value during the tectonic uplift period. This is a new method for calculating reservoir paleopressure. The parameters required in the calculation process are easy to obtain, the test cost of overburden porosity and rock formation compaction coefficient is low, and the paleopressure value of each historical time period can be calculated continuously. To a certain extent, it solves the problem that the previous paleopressure quantitative calculation method relies on microscopic fluid inclusion observation and testing, and it is difficult to continuously calculate the paleopressure of each geological historical period. It plays an important role in basin analysis and oil and gas reservoir dynamics research, and has important industrial application value in oil and gas exploration and evaluation. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] The specific effects of the present invention will be further described below in conjunction with the accompanying drawings and embodiments, in which:

[0062] Figure 1 It is a flow chart of a method for calculating paleopressure of clastic reservoirs based on volume increment according to an embodiment of the present invention;

[0063] Figure 2 is a graph showing the relationship between the compaction coefficient of a rock sample stratum and the increase of effective stress according to an embodiment of the present invention;

[0064] Figure 3 is a correlation diagram between effective stress and porosity of a clastic rock sample according to an embodiment of the present invention;

[0065] Figure 4 It is a burial depth-geological time evolution diagram of a well of 3500m in a dense clastic rock formation in a craton sedimentary basin according to an embodiment of the present invention;

[0066] Figure 5 It is a temperature-geological time evolution diagram of a well at 3500 m in a dense clastic rock formation in a craton sedimentary basin according to an embodiment of the present invention;

[0067] Figure 6 The present invention is an embodiment of calculating the paleopressure-geological age relationship diagram of a well 3500m deep in a dense clastic rock formation in a craton sedimentary basin;

[0068] Figure 7 It is a structural diagram of a clastic reservoir paleopressure calculation device based on volume increment according to an embodiment of the present invention. DETAILED DESCRIPTION

[0069] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0070] Embodiment 1:

[0071] refer to Figure 1 This embodiment provides a method for calculating paleopressure of clastic reservoirs based on volume increment, comprising the following steps:

[0072] S1: Establish the rock formation compaction coefficient C at any geological history time pct , pore volume V pt , the change in pore volume ΔV p and the change in effective stress Δσ efft The functional relationship between is the first expression:

[0073]

[0074] S2: The volume of pore fluid V at any geological time in the formation under the condition of formation sealing ft The current formation pore fluid volume V f0 The functional relationship between them is the second expression:

[0075] V f0 =V ft ·[1+α f (T0-T t )]·[1-β f (P p0 -P pt )]

[0076] The second expression satisfies V pt =V ft , ΔV p =ΔV f , ΔV f =V f0 -V ft ;

[0077] Further derivation through the formula, the second expression can be changed to:

[0078]

[0079] Where P p0 and T0 are the current measured formation pressure and temperature of the reservoir, which are a priori values; V f0 is the current volume of formation pore fluid; T t 、V ft , P pt and α ftare the formation temperature, pore fluid volume, pore fluid pressure and pore fluid thermal expansion coefficient at time t; β f is the pore fluid compressibility coefficient; ΔV p is the change in pore volume.

[0080] Furthermore, in clastic reservoirs, the pore fluid is mainly a mixed phase fluid composed of formation water and natural gas, and its thermal expansion coefficient α f and the compression factor β f It can be expressed by formula and Brie empirical formula respectively:

[0081] α f =(1-S w )·α fg +S w α fw

[0082]

[0083] In the formula, β fw , β fg are the compression coefficients of formation water and natural gas, respectively, which are a priori values; α fw , S w is the thermal expansion coefficient and water saturation of formation water, which are a priori values; m is the empirical coefficient, which is a priori value; α fg is the thermal expansion coefficient of natural gas, which can be obtained through the ideal state equation of gas:

[0084]

[0085] Where, T t are the formation temperatures at any geological time t.

[0086] The rock pores are always filled with fluid before and after the formation is uplifted, and the change in pore volume is equal to the change in fluid volume, that is, the following relationship exists:

[0087] V pt =V ft

[0088] ΔV p =ΔV f

[0089] Where V pt 、V ft are the pore volume and fluid volume at time t, respectively; ΔV p , ΔV f are the pore volume increment and fluid volume increment, respectively.

[0090] S3: Based on the first expression and the second expression, and the relationship between the pore volume change and the fluid volume change, a functional relationship between the rock formation compaction coefficient, the change in effective stress, and the temperature and pressure of the formation pore fluid is established, which is a third expression;

[0091] C pct ·Δσ efft =β f (P p0 -P pt )-α f (T0-T t )+α f (T0-T t )·β f (P p0 -P pt )

[0092] S4: Based on the calculation expression of the change in effective stress and the third expression, a calculation formula for the reservoir paleopressure at any geological time t is established, which is the fourth expression:

[0093]

[0094] In the formula, T0, P p0 and P r0 are the current measured reservoir formation temperature, pressure and overburden pressure, which are a priori values; T t , P pt , P rt , C pct and Δσ efft are the changes in formation temperature, formation pressure, overburden formation pressure, rock formation compaction coefficient and effective stress at any geological history time t; β f and α f are the pore fluid compressibility coefficient and pore fluid thermal expansion coefficient, V pt 、V ft are the pore volume and fluid volume at any geological time t, respectively; ΔV p , ΔV f are the pore volume increment and fluid volume increment respectively;

[0095] In step S4, the calculation expression of the change in effective stress is:

[0096] Δσ efft =[(P rt -P pt )-(P r0 -P p0 )].

[0097] S5: Obtain the rock formation compaction coefficient, overburden formation pressure and formation temperature at any geological historical time, combine the current measured formation temperature, pressure and overburden formation pressure of the reservoir, and calculate the reservoir paleopressure according to the fourth expression.

[0098] S5 specifically includes:

[0099] S51: Obtain the rock stratum compaction coefficient at any geological history time, and the specific acquisition method includes:

[0100] S511: Obtain sandstone samples of the clastic rock formation to be calculated (as shown in Table 1), and test the porosity φ and rock formation compaction coefficient C of the rock under normal pressure and different confining pressures (effective stresses). pc ;

[0101] Table 1 Core experimental sample information of a single well in the Craton Sedimentary Basin

[0102] Sample No. Depth(m) Lithology YP01 3500 Tight sandstone

[0103] Optionally, in step S511, the method for testing the compaction coefficient and porosity of the rock formation is: using a PoroPDP-200 overburden porosity measuring instrument to test the compaction coefficient and porosity of the rock formation using a helium method.

[0104] S512: Rock formation compaction coefficient C of clastic rock samples measured under different effective stresses PC Discrete values ​​( Figure 2 ), it can be seen that the rock formation compaction coefficient is well correlated with the effective stress of rock, and the property of effective stress acting on the rock skeleton is the same as the property of the rock as a whole when the confining pressure and pore pressure act together. Therefore, the correlation between effective stress and rock formation compaction coefficient fitted by experimental data can be used to predict the rock formation compaction coefficient in various historical periods.

[0105] S513: According to the rock formation compaction coefficient C PC and effective stress σ eff The power relationship is fitted to obtain the power relationship coefficient a, which has a good fit ( Figure 2 ); Select the rock sample YP01, the correlation between its effective stress and rock formation compaction coefficient is the fifth expression:

[0106]

[0107] In the formula, C pc is the rock formation compaction coefficient, Pa -1 ; σ eff is the effective stress, MPa.

[0108] S514: For clastic rock samples, the compaction process is mainly mechanical compaction, and the porosity change is directly related to the magnitude of the effective stress. According to a series of discrete values ​​of rock porosity and effective stress ( Figure 3 ), the power relationship between porosity and effective stress was fitted by the power fitting method, and the power relationship coefficients b and c were obtained. The determination coefficient (R-square) was 0.9891. Figure 3 It can be seen that the matching effect is good; the effective stress is calculated using the porosity of the historical period, which is the sixth expression:

[0109] σ eff = bφ c

[0110] In the formula, σ eff is the effective stress, MPa; φ is the porosity, %.

[0111] S515: According to the fifth expression and the sixth expression, the relationship between the rock formation compaction coefficient and the porosity is obtained, which is the seventh expression:

[0112]

[0113] In the formula, C pc is the rock formation compaction coefficient, Pa -1 ; φ is porosity, %; a, b, c are discrete value fitting coefficients; the seventh expression is used to obtain the rock stratum compaction coefficient at any geological historical time.

[0114] Optionally, in step S515, the fitting coefficient a can be obtained from Figure 2 The fitting coefficients b and c can be read from Figure 3 For the sample numbered YP01, a is 0.0000005, b is 574.74, and c is -2.385.

[0115] S516: Based on any geological history time t and stratum depth H t The functional relationship of is used to calculate the stratigraphic depth at any geological time:

[0116] H t =f(t)

[0117] Optionally, any geological history time t and stratigraphic depth H t The functional relationship can be simulated according to the basin burial history diagram ( Figure 4 ) is obtained. For example, the current burial depth of sample YP01 is 3500m. When t = 100Ma, the maximum burial depth H t It is 4013m.

[0118] S517: Based on the current depth-sound-measured porosity relationship index model, calculate the porosity φ at any geological history time t t :

[0119]

[0120] Where φ0 is the porosity at current normal pressure, a priori value; e is the base of the natural logarithm, a priori value; k is the compaction factor, a priori value; H t is the stratigraphic depth at any geological time t; H0 is the current stratigraphic depth, a priori value;

[0121] S517: Convert the rock stratum compaction coefficient and porosity in the seventh expression into values ​​at any geological historical time t, that is, obtain a calculation formula for the rock stratum compaction coefficient at any geological historical time:

[0122]

[0123] In the formula, φ t is the porosity at any geological history time t, and the rock stratum compaction coefficient at any geological history time is obtained by the above formula.

[0124] S52: Obtain the overburden stratum pressure at any geological history time. The specific calculation formula is as follows:

[0125] P rt =ρ s ·H t ·g

[0126] In the formula, ρ s is the empirical value of shallow stratum density, which is a priori value and is taken as 2.65 g / cm 3 ;H t is the depth of the stratum at any geological time t; g is the gravitational acceleration, which is 9.8 m / s 2 For example, the current burial depth of sample YP01 is 3500m, and when t=100Ma, the maximum burial depth H t When the overlying stratum pressure is 4013 m, P rt = 104.2MPa.

[0127] Alternatively, the overburden pressure at any geological time can be calculated based on the basin simulation burial depth-geological time evolution diagram ( Figure 4 )get.

[0128] S53: Obtaining the stratum temperature at any geological history time, the specific acquisition method is: obtaining according to the basin thermal history simulation temperature-geological time evolution diagram ( Figure 5 ).

[0129] S54: Based on the rock formation compaction coefficient, overburden formation pressure and formation temperature at any geological historical time obtained in steps S51-S53, combined with the current measured formation temperature, pressure and overburden formation pressure of the reservoir, the reservoir paleopressure is calculated according to the fourth expression.

[0130] The paleopressure value ( Figure 6 The solid line in the figure is highly consistent with the paleopressure value at the maximum burial depth restored by the mudstone equivalent depth method (the data points in Figure 6). This method can accurately calculate the paleopressure value of clastic reservoirs. It has stronger applicability and practicality than previous methods, and can continuously calculate the paleopressure values ​​of various historical periods, which has certain industrial application value.

[0131] This embodiment, through the analysis of the test data of the overburden porosity and rock formation compaction coefficient of the tight sandstone rock sample of the single well reservoir, combined with the definition of the rock formation compaction coefficient, deduced and established a theoretical formula to characterize the change of the rock formation compaction coefficient with depth (time) during the tectonic uplift period; fully considering the coexistence of multiphase fluids under formation conditions, the theoretical equation of the change in the volume of pore fluids in the closed system before and after the tectonic uplift was derived, and the calculation formula of the reservoir paleopressure was solved. Taking the current measured reservoir pressure and temperature as the starting point, combined with the simulated formation thermal evolution history paleotemperature curve, the reservoir paleopressure value during the entire tectonic uplift period is calculated.

[0132] This embodiment proposes a method for calculating paleopressure in clastic reservoirs, aiming at the current difficult problem of universal applicability and continuous paleopressure quantitative calculation in clastic reservoirs. This method calculates paleopressure based on volume increment, which solves the problem that the previous paleopressure quantitative calculation methods rely on microscopic fluid inclusion observation and testing, and it is difficult to continuously calculate the paleopressure in various geological historical periods. By comparing the paleopressure values ​​simulated and calculated by the method of the present invention with the paleopressure values ​​of the maximum burial depth period restored by the mudstone acoustic time difference method or the paleopressure results restored by the fluid inclusion laser Raman test, it can be seen that this method achieves better results in restoring the paleopressure values ​​of the reservoir during the tectonic uplift period, has stronger applicability and practicality than previous methods, and can continuously calculate the paleopressure values ​​of the entire tectonic uplift period, and has certain industrial application value.

[0133] Embodiment 2:

[0134] refer to Figure 7 This embodiment provides a clastic reservoir paleopressure calculation device based on volume increment, including the following modules:

[0135] The first expression building module 1 is used to establish the rock stratum compaction coefficient C at any geological history time. pct , pore volume Vpt , the change in pore volume ΔV p and the change in effective stress Δσ efft The functional relationship between is the first expression:

[0136]

[0137] The second expression building module 2 is used to obtain the formation pore fluid volume V at any geological history time under the formation sealing condition. ft The current formation pore fluid volume V f0 The functional relationship between them is the second expression:

[0138] V f0 =V ft ·[1+α f (T0-T t )]·[1-β f (P p0 -P pt )]

[0139] The second expression satisfies V pt =V ft , ΔV p =ΔV f , ΔV f =V f0 -V ft ;

[0140] A third expression establishing module 3 is used to establish a functional relationship between the rock formation compaction coefficient, the change in effective stress, and the temperature and pressure of the formation pore fluid according to the first expression and the second expression, which is a third expression;

[0141] C pct ·Δσ efft =β f (P p0 -P pt )-α f (T0-T t )+α f (T0-T t )·β f (P p0 -P pt )

[0142] The fourth expression establishment module 4 is used to establish a reservoir paleopressure calculation formula at any geological time t according to the calculation expression of the change in effective stress and the third expression, which is the fourth expression:

[0143]

[0144] In the formula, T0, P p0 and P r0 are the current measured reservoir formation temperature, pressure and overburden pressure, which are a priori values; T t , P pt , P rt , C pct and Δσ efft are the changes in formation temperature, formation pressure, overburden formation pressure, rock formation compaction coefficient and effective stress at any geological history time t; β f and α f are the pore fluid compressibility coefficient and pore fluid thermal expansion coefficient, V pt 、V ft are the pore volume and fluid volume at any geological time t, respectively; ΔV p , ΔV f are the pore volume increment and fluid volume increment respectively;

[0145] The reservoir paleopressure calculation module 5 is used to obtain the rock formation compaction coefficient, overburden formation pressure and formation temperature at any geological history time, and calculate the reservoir paleopressure according to the fourth expression in combination with the current measured formation temperature, pressure and overburden formation pressure of the reservoir.

[0146] The above-mentioned clastic reservoir paleopressure calculation device is used to implement each process of the clastic reservoir paleopressure calculation method embodiment described in Example 1, and can achieve the same technical effect.

[0147] Embodiment three:

[0148] This embodiment provides a computer device, which includes a memory and a processor. The memory stores a computer program. When the computer program is executed by the processor, the various processes of the embodiment of the method for calculating the paleopressure of clastic reservoirs are executed, and the same technical effect can be achieved. To avoid repetition, it will not be repeated here.

[0149] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or system including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or system. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or system including the element.

[0150] The serial numbers of the embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments. In a unit claim that lists several means, several of these means may be embodied by the same hardware item. The use of the words first, second, and third, etc. does not indicate any order and these words may be interpreted as identifiers.

[0151] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for calculating paleopressure of clastic reservoirs, characterized in that: The following steps are involved: Establish the rock formation compaction coefficient C at any geological history time pct , pore volume V pt , the change in pore volume ΔV p and the change in effective stress Δσ efft The functional relationship between is the first expression: Based on the formation sealing condition, the formation pore fluid volume V at any geological history time ft The current formation pore fluid volume V f0 The functional relationship between them is the second expression: V f0 =V ft ·[1+α f (T0-T t )]·[1-β f (P p0 -P pt )] The second expression satisfies V pt =V ft , ΔV p =ΔV f , ΔV f =V f0 -V ft ; According to the first expression and the second expression, a functional relationship between the rock formation compaction coefficient, the change in effective stress, and the temperature and pressure of the formation pore fluid is established, which is a third expression; C pct ·Δσ efft =β f (P p0 -P pt )-α f (T0-T t )+α f (T0-T t )·β f (P p0 -P pt ) According to the calculation expression of the change in effective stress and the third expression, a calculation formula for reservoir paleopressure at any geological time t is established, which is the fourth expression: In the formula, T0, P p0 and P r0 are the current measured reservoir formation temperature, pressure and overburden pressure, which are a priori values; T t , P pt , P rt , C pct and Δσ efft are the changes in formation temperature, formation pressure, overburden formation pressure, rock formation compaction coefficient and effective stress at any geological history time t; β f and α f are the pore fluid compressibility coefficient and pore fluid thermal expansion coefficient, V pt 、V ft are the pore volume and fluid volume at any geological time t, respectively; ΔV p , ΔV f are the pore volume increment and fluid volume increment respectively; Obtain the rock formation compaction coefficient, overburden formation pressure and formation temperature at any geological history time, combine the current measured formation temperature, pressure and overburden formation pressure of the reservoir, and calculate the reservoir paleopressure according to the fourth expression.

2. A method for calculating paleopressure of clastic reservoirs according to claim 1, characterized in that: Also includes: Obtain the rock formation compaction coefficient C of clastic rock samples under different effective stresses pc A series of discrete values ​​of , through the data fitting method, the fitting relationship between effective stress and rock formation compaction coefficient is constructed as the fifth expression: A series of discrete values ​​of the rock porosity φ of the clastic rock samples under different effective stresses are obtained, and the power fitting method is used to construct the fitting relationship between effective stress and rock porosity, which is the sixth expression: s eff =bφ c According to the fifth expression and the sixth expression, the relationship between the rock formation compaction coefficient and the porosity is obtained, which is the seventh expression: In the formula, C pc is the rock formation compaction coefficient, Pa -1 ; φ is porosity, %; a, b, c are discrete value fitting coefficients; the seventh expression is used to obtain the rock stratum compaction coefficient at any geological historical time.

3. A method for calculating paleopressure of clastic reservoirs according to claim 2, characterized in that: The PoroPDP-200 overburden porosity measuring instrument was used to test the compaction coefficient and porosity of rock formations using the helium method.

4. A method for calculating paleopressure of clastic reservoirs according to claim 1, characterized in that: The pore fluid thermal expansion coefficient α f and the pore fluid compressibility coefficient β f They are calculated by the following formulas: a f =(1-S w )·a fg +S w ·a fw In the formula, β fw , β fg are the compressibility coefficients of formation water and natural gas, respectively, which are a priori values; α fw , S w is the thermal expansion coefficient and water saturation of formation water, which are a priori values; m is the empirical coefficient, which is a priori value; α fg is the thermal expansion coefficient of natural gas.

5. The method for calculating paleopressure of a clastic reservoir according to claim 1, characterized in that: The calculation expression of the change of the effective stress is: Δσ efft =[(P rt -P pt )-(P r0 -P p0 )]。 6. A method for calculating paleopressure of clastic reservoirs according to claim 2, characterized in that: The step of obtaining the rock formation compaction coefficient at any geological history time includes: According to any geological history time t and stratum depth H t The functional relationship of is used to calculate the stratigraphic depth at any geological time: H t =f(t) According to the current depth-sonic-measured porosity relationship index model, the porosity φ at any geological history time t is calculated. t : Where φ0 is the porosity at current normal pressure, a priori value; e is the base of the natural logarithm, a priori value; k is the compaction factor, a priori value; H t is the stratigraphic depth at any geological time t; H0 is the current stratigraphic depth, a priori value; The rock formation compaction coefficient and porosity in the seventh expression are converted into values ​​at any geological historical time t, that is, the calculation formula of the rock formation compaction coefficient at any geological historical time is obtained: In the formula, φ t is the porosity at any geological time t.

7. A method for calculating paleopressure of clastic reservoirs according to claim 1, characterized in that: The calculation formula for obtaining the overburden pressure at any geological history time is as follows: P rt =ρ s ·H t ·g In the formula, ρ s is the empirical value of shallow stratum density, which is a priori value; H t is the depth of the stratum at any geological time t; g is the gravitational acceleration.

8. A method for calculating paleopressure of clastic reservoirs according to claim 1, characterized in that: The formation temperature at any geological history time is obtained by a specific method: obtaining it according to a basin thermal history simulation temperature-geological time evolution diagram.

9. A clastic reservoir paleopressure calculation device, characterized in that: Includes the following modules: The first expression building module is used to establish the rock stratum compaction coefficient C at any geological history time. pct , pore volume V pt , the change in pore volume ΔV p and the change in effective stress Δσ efft The functional relationship between is the first expression: The second expression building module is used to obtain the formation pore fluid volume V at any geological history time under formation sealing conditions. ft The current formation pore fluid volume V f0 The functional relationship between them is the second expression: V f0 =V ft ·[1+α f (T0-T t )]·[1-β f (P p0 -P pt )] The second expression satisfies V pt =V ft , ΔV p =ΔV f , ΔV f =V f0 -V ft ; A third expression building module is used to build a functional relationship between the rock formation compaction coefficient, the change in effective stress, and the temperature and pressure of the formation pore fluid according to the first expression and the second expression, which is a third expression; C pct ·Δσ efft =β f (P p0 -P pt )-α f (T0-T t )+α f (T0-T t )·β f (P p0 -P pt ) The fourth expression establishment module is used to establish a reservoir paleopressure calculation formula at any geological time t according to the calculation expression of the change in effective stress and the third expression, which is the fourth expression: In the formula, T0, P p0 and P r0 are the current measured reservoir formation temperature, pressure and overburden pressure, which are a priori values; T t , P pt , P rt , C pct and Δσ efft are the changes in formation temperature, formation pressure, overburden formation pressure, rock formation compaction coefficient and effective stress at any geological history time t; β f and α f are the pore fluid compressibility coefficient and pore fluid thermal expansion coefficient, V pt 、V ft are the pore volume and fluid volume at any geological time t, respectively; ΔV p , ΔV f are the pore volume increment and fluid volume increment respectively; The reservoir paleopressure calculation module is used to obtain the rock formation compaction coefficient, overburden formation pressure and formation temperature at any geological history time, and combine the current measured reservoir formation temperature, pressure and overburden formation pressure to calculate the reservoir paleopressure according to the fourth expression.

10. A computer device, characterized in that: The computer device includes a memory and a processor, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the method for calculating the paleopressure of clastic reservoirs as described in any one of claims 1 to 8 is executed.

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