Method and equipment for evaluating loss amount of ancient natural gas reservoir and storage medium

Abstract

The invention provides an ancient natural gas reservoir loss amount evaluation method and device and a storage medium, and belongs to the field of petroleum and natural gas geological exploration, and the evaluation method comprises the steps: dividing the geological evolution time from gas reservoir formation to current into a plurality of geological time periods; determining the total natural gas loss amount in different geological time periods; on the basis of the natural gas density reduction proportion in different geological time periods, the diffusion loss amount of natural gas with gas reservoir loss in a diffusion form in different geological time periods is determined; and determining the difference between the total natural gas loss amount and the natural gas diffusion loss amount in different geological time periods as the loss amount of other natural gas subjected to gas reservoir loss in other forms. The method provided by the invention can be used for evaluating the loss amount and loss time of natural gas in different forms such as natural gas diffusion loss and natural gas permeation loss, and the calculation result is high in accuracy.

Description

Technical Field

[0001] The invention relates to the technical field of petroleum and natural gas geological exploration, and in particular to a method for evaluating the loss of ancient natural gas reservoirs and an electronic device. Background Art

[0002] For gas reservoirs that have already accumulated, the loss of natural gas directly affects the preservation conditions of the gas reservoir in the later stage. Especially for deep and ancient gas reservoirs, the gas reservoirs have been formed for a long time, and although the loss of natural gas is slow, it is easy to "accumulate a little bit into a lot". The evaluation of the loss amount and loss time of natural gas reservoirs is important for the exploration of natural gas reservoirs.

[0003] Conventional caprock natural gas loss mainly focuses on diffusion evaluation, which mainly uses a single-layer caprock model to calculate the gas reservoir diffusion and quantitatively evaluate the gas reservoir loss process. However, the existing methods have the following disadvantages:

[0004] (1) The existing technology is only used to evaluate the amount of natural gas loss in the form of diffusion, and cannot consider other forms of natural gas loss such as seepage;

[0005] (2) The existing technology requires a series of input parameters, but the existing diffusion calculation model is static, that is, it can only calculate the diffusion of the gas reservoir from its formation to the present day based on the current gas reservoir's burial depth, temperature, pressure, formation thickness, and formation diffusion coefficient as input parameters. This is suitable for gas reservoirs whose geological parameters do not change much after the formation of the gas reservoir due to the burial depth and the deposition and compaction of the overlying formations. However, for deep and ancient gas reservoirs, the above parameters may change, resulting in poor reliability of the calculation results.

[0006] (3) Whether the diffusion calculation results are accurate or not is not limited by reference standards. Summary of the invention

[0007] In view of the technical problem that other forms of natural gas loss such as permeation cannot be considered in the prior art, the present invention provides a method for evaluating the loss amount of ancient natural gas reservoirs. This method can be used to evaluate the amount and time of natural gas loss in different forms such as natural gas diffusion loss and natural gas permeation loss.

[0008] To achieve the above-mentioned purpose, the first aspect of the present invention provides a method for evaluating the loss of ancient natural gas reservoirs, the evaluation method comprising the following steps: dividing the geological evolution time from the formation of the gas reservoir to the present into multiple geological time periods; determining the total amount of natural gas loss in different geological time periods; determining the amount of natural gas loss due to diffusion from the gas reservoir in different geological time periods based on the reduction ratio of natural gas density in different geological time periods; determining the difference between the total amount of natural gas loss in different geological time periods and the amount of natural gas loss due to diffusion as the amount of other natural gas loss due to gas reservoir loss in other forms; wherein the geological time period refers to the time range between two adjacent geological moments.

[0009] In an exemplary embodiment of the present invention, the evaluation method may further include: adding the total amount of natural gas loss in different geological time periods to obtain the total cumulative natural gas loss of the gas reservoir; adding the amount of natural gas diffusion loss that occurs in the gas reservoir in the form of diffusion in different geological time periods to obtain the cumulative natural gas diffusion loss of the gas reservoir through the overlying strata of the gas reservoir; adding the amount of other natural gas diffusion loss that occurs in other forms of gas reservoir loss in different geological time periods to obtain the cumulative natural gas loss of the gas reservoir in forms other than diffusion.

[0010] In an exemplary embodiment of the present invention, the evaluation method may further include: determining whether the difference between the total amount of natural gas loss and the natural gas diffusion loss in each geological time period is less than zero; if the difference is less than zero, adjusting the input parameters for calculating the natural gas diffusion loss to obtain a new natural gas diffusion loss; if the difference is greater than or equal to zero, determining the difference between the total amount of natural gas loss and the natural gas diffusion loss in the geological time period as other natural gas loss caused by gas reservoir loss in other forms.

[0011] In an exemplary embodiment of the present invention, the calculation formula for the total amount of natural gas loss in different geological time periods may be: Among them, G loss,i is the time from the i-th geological moment t i To the i+1th geological moment t i+1 Total amount of natural gas loss, m 3 ; G i is the i-th geological moment t i Gas reservoir volume under standard conditions, m 3 ρ i is the i-th geological moment t i The density of natural gas in the gas reservoir, kg / m 3 ρ i+1 is the i+1th geological time t i+1 The density of natural gas in the gas reservoir, kg / m 3; i = 1, 2, 3...n, t1 represents the current geological time, t n represents the time of gas reservoir formation, t i represents the i-th geological moment.

[0012] In an exemplary embodiment of the present invention, determining the amount of natural gas lost from a gas reservoir in the form of diffusion in different geological time periods may include: determining the amount of natural gas diffused through a cap layer per unit area in different geological time periods; determining the area of ​​the gas reservoir in different geological time periods; and determining the amount of natural gas lost from a gas reservoir in the form of diffusion in different geological time periods based on the area of ​​the gas reservoir in different geological time periods and the amount of natural gas diffused through a cap layer per unit area.

[0013] In an exemplary embodiment of the present invention, when the overlying stratum of the gas reservoir is a single-layer cap layer, the calculation formula for the diffusion amount of natural gas through the cap layer per unit area in the different geological time periods can be:

[0014]

[0015] Among them, q i is the time from the i-th geological moment t i To the i+1th geological time t i+1 The amount of natural gas diffused through the cap rock per unit area during this geological period, kg / m 2 ;D e is the diffusion coefficient of the saturated water sample, m 2 / s; h is the thickness of the single-layer cap layer, m; c1 is the gas concentration at the interface between the gas and the cap layer, kg / m 3 .

[0016] In an exemplary embodiment of the present invention, when the overlying strata of the gas reservoir are multiple reservoir-caprock combinations, the calculation formula for the diffusion amount of natural gas through the caprock per unit area in different geological time periods may be:

[0017]

[0018] c 1i =φ i ρ wi S gi ;

[0019] Among them, q i is the time from the i-th geological moment t i To the i+1th geological time t i+1 The diffusion amount per unit area, kg / m 2 ;D ei is the overlying stratum of the gas reservoir at the i-th geological time t i The comprehensive diffusion coefficient, 10 -10m 2 / s;h ji is the jth lithologic stratum contained in the overlying strata of the gas reservoir at the i-th geological time t i Thickness, m; j = 1, 2, 3, ...; c 1i is the i-th geological moment t i Gas concentration at the interface between the gas and the direct cap layer, kg / m 3 ; φ i is the i-th geological moment t i The porosity of the sample, %; ρ wi is the i-th geological moment t i Density of formation water, kg / m 3 ; S gi is the i-th geological moment t i Solubility of natural gas in formation water under actual temperature and pressure conditions, mol / kg.

[0020] In an exemplary embodiment of the present invention, the evaluation method may further include: determining the total amount of accumulated natural gas loss in the gas reservoir based on the gas reservoir volume and the natural gas density in the gas reservoir under standard conditions at the current geological time, and the natural gas density in the gas reservoir at the time of gas reservoir formation.

[0021] A second aspect of the present invention provides an electronic device, comprising a processor and a memory, wherein the memory stores at least one computer program, and the at least one computer program is loaded and executed by one or more of the above-mentioned processors so that the processor executes the above-mentioned ancient natural gas reservoir loss assessment method.

[0022] The third aspect of the present invention provides a computer-readable storage medium, characterized in that the computer-readable storage medium stores at least one program code, and the program code is loaded and executed by a processor to enable the computer to execute the above-mentioned ancient natural gas reservoir loss evaluation method.

[0023] Through the technical solution provided by the present invention, the present invention has at least the following technical effects:

[0024] (1) The method for evaluating the loss of ancient natural gas reservoirs provided by the present invention can be used to evaluate the loss and loss time of natural gas in different forms such as natural gas diffusion loss and natural gas permeation loss;

[0025] (2) The present invention requires fewer parameters for calculating the loss of natural gas reservoirs, which are easy to obtain, and the calculation is simple and the result is highly accurate;

[0026] (3) The present invention can limit the calculation result of the diffusion amount. The natural gas loss amount should be greater than or equal to the diffusion amount. If the natural gas loss amount is much lower than the diffusion amount, it means that the calculation result of the diffusion amount is too high, and the input parameters should be adjusted and recalculated.

[0027] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings:

[0029] Figure 1 A flow chart of a method for evaluating the amount of lost gas in ancient natural gas reservoirs provided in an embodiment of the present invention;

[0030] Figure 2 A schematic diagram of the calculation principle of the amount of lost gas from ancient natural gas reservoirs provided in an embodiment of the present invention;

[0031] Figure 3 A gas reservoir burial history curve diagram provided by an embodiment of the present invention;

[0032] Figure 4 A schematic diagram of diffusion correction provided by an embodiment of the present invention;

[0033] Figure 5 A schematic diagram of the structure of an electronic device provided by an embodiment of the present invention.

[0034] Description of Reference Numerals

[0035] 201 - processor, 202 - memory. DETAILED DESCRIPTION

[0036] The specific implementation of the embodiment of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiment of the present invention, and is not used to limit the embodiment of the present invention.

[0037] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0038] In the present invention, unless otherwise specified, the directional words used, such as "upper, lower, top, bottom", are usually used to describe the relative positional relationship of the components in terms of the directions shown in the drawings or in terms of the vertical, perpendicular or gravity directions. "First", "second", etc. are only used for the convenience of description and distinction, and cannot be understood as indicating or implying relative importance.

[0039] In the prior art, the loss of natural gas in gas reservoirs includes natural gas diffusion loss, natural gas permeation loss, water dissolution loss and biodegradation loss, among which natural gas diffusion loss has a greater impact. At present, the evaluation of natural gas loss mainly focuses on the calculation of natural gas diffusion loss, and does not consider the natural gas loss in other forms such as seepage. In addition, the current natural gas diffusion loss is often determined based on the natural gas diffusion loss calculation model, but the diffusion calculation model is static, that is, it can only use the current gas reservoir burial depth, temperature, pressure, formation thickness, and formation diffusion coefficient as input parameters to calculate the diffusion of the gas reservoir from its formation to the present. It is suitable for gas reservoirs whose geological parameters do not change much after the formation of the gas reservoir due to the burial depth and deposition and compaction of the overlying strata. However, for deep and ancient gas reservoirs, the above parameters may change, resulting in poor credibility of the calculation results.

[0040] In order to solve the above technical problems, the present invention has formed a new method for evaluating the loss of ancient natural gas reservoirs. The overall technical concept of the method is: dividing the geological time from the formation of the gas reservoir to the present into multiple geological time periods, and calculating the total amount of natural gas loss by determining the ratio of natural gas density reduction in each geological time period; then considering the changes in geological parameters such as gas reservoir burial depth, formation thickness, temperature, pressure, diffusion coefficient, etc. in different geological time periods, dynamically calculate the natural gas diffusion loss in different geological time periods; finally, determine other forms of natural gas loss based on the difference between the total amount of natural gas loss in each geological time period and the natural gas diffusion loss.

[0041] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0042] Embodiment 1

[0043] Please refer to Figure 1 The first embodiment of the present invention provides a method for evaluating the amount of lost gas in ancient natural gas reservoirs, the method comprising the following steps:

[0044] Step S101: Divide the geological evolution time from the formation of the gas reservoir to the present into multiple geological time periods.

[0045] If t i represents any geological moment, i = 1, 2, 3...n, t1 represents the present moment, t n represents the time of gas reservoir formation, then the time range between any two adjacent geological moments [t i , t i+1 ] can represent a geological time period.

[0046] Here, the time interval lengths corresponding to any two geological time periods may be equal or unequal. For example, n geological moments may be selected from the geological evolution time from the formation of the gas reservoir to the present according to the same time interval length (e.g., 5, 10, 15, 20 million years, etc.), and then n-1 equally divided geological time periods may be divided; or n geological moments may be selected from the geological evolution time from the formation of the gas reservoir to the present according to different time interval lengths (e.g., according to time interval lengths that increase or decrease successively), and then n-1 unequally divided geological time periods may be divided.

[0047] Step S102: determining the total amount of natural gas lost in different geological time periods based on the natural gas density reduction ratio in different geological time periods.

[0048] like Figure 2 As shown in the figure, assuming that the trapped volume remains unchanged after the gas reservoir is finalized, and the pore volume of the reservoir remains unchanged, according to the gas state equation, if the gas reservoir does not lose gas, the mass remains unchanged, and the natural gas density does not change; but if loss occurs, the temperature and pressure of the gas reservoir change, the natural gas density will decrease, and the natural gas density reduction ratio is the natural gas loss ratio, which can be used to obtain the total amount of natural gas loss. Therefore, by determining the natural gas density reduction ratio in different geological time periods, the total amount of natural gas loss in different geological time periods can be determined.

[0049] For example, the process of calculating the total amount of natural gas lost in different geological time periods is as follows:

[0050] The relationship between gas mass, density and volume is as shown in formula (1):

[0051] m=ρ(P,T)×V (1)

[0052] Where m is the gas mass, (kg); V is the gas volume, m 3 ; ρ is gas density, kg / m 3 .

[0053] The mass of natural gas in a gas reservoir is proportional to its density, and inversely proportional to its volume, as shown in formula (2):

[0054]

[0055] In the formula, m i+1 represents the geological time t i+1 The mass of natural gas in the gas reservoir, kg; m i represents the geological time t i The mass of natural gas in the gas reservoir, kg; V i+1 represents the geological time t i+1 The volume of natural gas in the gas reservoir, m 3 ; Vi represents the geological time t i The volume of natural gas in the gas reservoir, m 3 ρ i+1 represents the geological time t i+1 The density of natural gas in the gas reservoir, kg / m 3 ρ i represents the geological time t i The density of natural gas in the gas reservoir, kg / m 3 .

[0056] Under the premise that the volume occupied by the gas remains unchanged, formula (2) can be simplified to formula (3):

[0057]

[0058] In the expression of industrial natural gas reserves, gas reservoir quality is often expressed by the gas reservoir volume under standard conditions (20°C, 0.101MPa). The gas reservoir quality is proportional to the gas reservoir volume under standard conditions, as shown in formula (4):

[0059]

[0060] In the formula, m i+1 represents the geological time t i+1 The mass of natural gas in the gas reservoir, kg; m i represents the geological time t i The mass of natural gas in the gas reservoir, kg; G i+1 represents the geological time t i+1 The volume of natural gas in the gas reservoir under standard conditions (referred to as the gas reservoir volume under standard conditions), m 3 ; G i represents the geological time t i The volume of natural gas in the reservoir under standard conditions, m 3 .

[0061] Combining formula (3) and formula (4), we can get the relationship between gas reservoir volume and natural gas density, as shown in formula (5):

[0062]

[0063] Therefore, from the geological time t i To geological time t i+1 The total amount of natural gas loss can be expressed as formula (6):

[0064] G loss,i =G i+1 -G i (6)

[0065] Combining formula (5) and formula (6), the natural gas density can be calculated from the geological time t iTo geological time t i+1 The total amount of natural gas loss is as shown in formula (7):

[0066]

[0067] In the formula, G loss,i Denotes the time from geological time t i To geological time t i+1 Total amount of natural gas lost, m 3 ρ i+1 represents the geological time t i+1 The density of natural gas in the gas reservoir, kg / m 3 ρ i represents the geological time t i The density of natural gas in the gas reservoir, kg / m 3 ; G i represents the geological time t i The volume of natural gas in the reservoir under standard conditions, m 3 .

[0068] Step S103: Determine the amount of natural gas lost from the gas reservoir in the form of diffusion in different geological time periods.

[0069] Exemplarily, the process of determining the amount of natural gas lost from a gas reservoir in the form of diffusion in different geological time periods includes but is not limited to the following sub-steps S1031 to S1033.

[0070] Sub-step S1031: Determine the diffusion amount of natural gas through the cap layer per unit area in different geological time periods.

[0071] If the overlying stratum of the gas reservoir is a single-layer cap layer, then the diffusion amount of natural gas through the cap layer per unit area in different geological time periods can be calculated using formula (8).

[0072]

[0073] In the formula, q i is the time from the i-th geological moment t i To the i+1th geological time t i+1 The amount of natural gas diffused through the cap rock per unit area during this geological period, kg / m 2 ;D e is the diffusion coefficient of the saturated water sample, m 2 / s; h is the thickness of the single-layer cap layer, m; c1 is the gas concentration at the interface between the gas and the cap layer, kg / m 3 .

[0074] If the overlying strata of the gas reservoir are multiple reservoir-caprock combinations, then the diffusion amount of natural gas through the caprock per unit area in different geological time periods can be calculated using formulas (9) to (12).

[0075]

[0076] c 1i =φ i ρ wi S gi (10)

[0077]

[0078] D ji =a×k i / (φ i ×μ i ×1 / p i ) (12)

[0079] In the formula, q i is the time from the i-th geological moment t i To the i+1th geological time t i+1 The diffusion amount per unit area, kg / m 2 ;D ei is the overlying stratum of the gas reservoir at the i-th geological time t i The comprehensive diffusion coefficient, 10 -10 m 2 / s;h ji is the jth lithologic stratum contained in the overlying strata of the gas reservoir at the i-th geological time t i Thickness, m; j = 1, 2, 3...; D ji is the jth lithologic stratum overlying the gas reservoir at the i-th geological time t i The effective diffusion coefficient, m 2 / s;c 1i is the i-th geological moment t i Gas concentration at the interface between the gas and the direct cap layer, kg / m 3 ; φ i is the i-th geological moment t i The porosity of the sample, %; ρ wi is the i-th geological moment t i Density of formation water, kg / m 3 ; S gi is the i-th geological moment t i Solubility of natural gas in formation water under actual temperature and pressure conditions, mol / kg.

[0080] Sub-step S1032: Determine the gas reservoir area in different geological time periods.

[0081] Sub-step S1033: Based on the gas reservoir area and the diffusion amount of natural gas through the cap layer per unit area in different geological time periods, determine the amount of natural gas lost from the gas reservoir in the form of diffusion in different geological time periods.

[0082] For example, the amount of natural gas lost from a gas reservoir in the form of diffusion in different geological time periods can be calculated using formula (13).

[0083]

[0084] In the formula, G diff,i Denotes the time from geological time t i To geological time t i+1 Natural gas diffusion loss, m 3 ; A is the gas reservoir area, m 2 ;q i represents the time from the i-th geological moment t i To the i+1th geological time t i+1 The diffusion amount per unit area, kg / m 2 ρ std Indicates the density of natural gas under standard conditions (20℃, 0.101MPa), unit: kg / m 3 .

[0085] Step S104: Determine the difference between the total amount of natural gas lost in different geological time periods and the amount of natural gas lost by diffusion as other natural gas lost in gas reservoirs in other forms.

[0086] The calculation formula for other natural gas loss in different geological time periods is as follows:

[0087] G other,i =G loss,i -G diff,i (14)

[0088] In the formula, G other,i Denotes the time from geological time t i To geological time t i+1 Other natural gas loss, m 3 ; G loss,i Denotes the time from geological time t i To geological time t i+1 Total amount of natural gas lost, m 3 ; G diff,i Denotes the time from geological time t i To geological time t i+1 Natural gas diffusion loss, m 3 .

[0089] Furthermore, in this embodiment, in order to limit the calculation result of the natural gas diffusion loss, it is necessary to determine whether the difference between the total amount of natural gas loss in different geological time periods and the natural gas diffusion loss conforms to the gas reservoir loss law.

[0090] Specifically, the step S104 further includes the following sub-steps:

[0091] Sub-step S1041: Calculate the difference between the total amount of natural gas loss and the amount of natural gas diffusion loss in different geological time periods.

[0092] Sub-step S1042: Determine whether the difference between the total amount of natural gas loss and the amount of natural gas diffusion loss in each geological time period is less than zero.

[0093] Sub-step S1043A: If the difference is less than zero, adjust the calculated natural gas diffusion loss G diff,i input parameters to obtain the new natural gas diffusion loss.

[0094] Sub-step S1043B: If the difference is greater than or equal to zero, the difference between the total amount of natural gas lost in the geological time period and the amount of natural gas lost by diffusion is determined as the other amount of natural gas lost from the gas reservoir in other forms.

[0095] Furthermore, in this embodiment, the evaluation method further includes steps S105 to S107.

[0096] Step S105: Add up the total amount of natural gas lost in different geological time periods to obtain the total amount of accumulated natural gas lost in the gas reservoir.

[0097] Specifically, the calculation formula for the total amount of accumulated natural gas loss in the gas reservoir is as follows:

[0098] G c,loss =G loss,1 +G loss,2 +G loss,3 ……+G loss,i ……+G loss,n-1 (15)

[0099] In the formula, G c,loss Indicates the total amount of natural gas lost from the gas reservoir during the geological evolution period from the formation of the gas reservoir to the present, m 3 ; G loss,i Denotes the time from geological time t i To geological time t i+1 Total amount of natural gas lost, m 3 ; G loss,1 represents the total amount of natural gas lost from geological time t1 to geological time t2, m 3 ; G loss,2represents the total amount of natural gas lost from geological time t2 to geological time t3, m 3 ; G loss,3 represents the total amount of natural gas lost from geological time t3 to geological time t4, m 3 ; G loss,n-1 Denotes the time from geological time t n-1 To geological time t n Total amount of natural gas lost, m 3 .

[0100] Step S106: Add up the natural gas diffusion loss from the gas reservoir in the form of diffusion in different geological time periods to obtain the cumulative natural gas diffusion loss from the gas reservoir through the overlying strata of the gas reservoir.

[0101] Specifically, the calculation formula for the cumulative natural gas diffusion loss in the gas reservoir is as follows:

[0102] G c,diff =G diff,1 +G diff,2 +G diff,3 ……+G diff,i ……+G diff,n-1 (16)

[0103] In the formula, G c,diff Indicates the amount of natural gas diffusion and loss during the geological evolution from the formation of the gas reservoir to the present, m 3 ; G diff,i Denotes the time from geological time t i To geological time t i+1 Natural gas diffusion loss, m 3 ; G diff,1 represents the amount of natural gas diffusion loss from geological time t1 to geological time t2, m 3 ; G diff,2 represents the amount of natural gas diffusion loss from geological time t2 to geological time t3, m 3 ; G diff,3 represents the amount of natural gas diffusion loss from geological time t3 to geological time t4, m 3 ; G diff,n-1 Denotes the time from geological time t n-1 To geological time t n Natural gas diffusion loss, m 3 .

[0104] Step S107: Add up the other natural gas losses that occur in gas reservoirs in other forms during different geological time periods to obtain the cumulative natural gas losses in gas reservoirs in other forms except diffusion.

[0105] Specifically, the calculation formula for the cumulative natural gas loss of gas reservoirs in other forms except diffusion is as follows:

[0106] G c,other =G other,1 +G other,2 +G other,3 ……+G other,i ……+G other,n-1 (17)

[0107] In the formula, G c,other Indicates the cumulative amount of natural gas lost from gas reservoirs in forms other than diffusion from the formation of gas reservoirs to the present geological evolution time, m 3 ; G other,i Denotes the time from geological time t i To geological time t i+1 Other natural gas loss, m 3 ; G other,1 represents the amount of other natural gas lost from geological time t1 to geological time t2, m 3 ; G other,2 represents the amount of other natural gas lost from geological time t2 to geological time t3, m 3 ; G other,3 represents the amount of other natural gas lost from geological time t3 to geological time t4, m 3 ; G other,n-1 Denotes the time from geological time t n-1 To geological time t n Other natural gas loss, m 3 .

[0108] Furthermore, in this embodiment, if it is necessary to quickly calculate the total amount of natural gas lost from the formation of the gas reservoir to the present, the calculation process can also be simplified to directly determine the total amount of cumulative natural gas lost from the gas reservoir based on the gas reservoir volume and the natural gas density in the gas reservoir under standard conditions at the current geological time, as well as the natural gas density in the gas reservoir at the time of gas reservoir formation.

[0109] Specifically, the simplified calculation formula for the total amount of accumulated natural gas loss in the gas reservoir is as follows:

[0110]

[0111] In the formula, G c,loss Indicates the total amount of natural gas lost from the gas reservoir during the geological evolution period from the formation of the gas reservoir to the present, m 3 ; G1 is the gas reservoir volume under standard conditions at present geological time, m 3 ρ n is the natural gas density in the gas reservoir at the time of gas reservoir formation, kg / m 3 ; ρ1 is the natural gas density in the gas reservoir at the current geological time, kg / m 3 .

[0112] It should be noted that if the purpose of the study is to quickly estimate the total amount of cumulative natural gas loss from the formation of the gas reservoir to the present, it is not necessary to divide the geological evolution time from the formation of the gas reservoir to the present into multiple geological time periods to calculate the total amount of natural gas loss in different geological time periods separately, and then obtain the total amount of cumulative natural gas loss by accumulation. The above calculation process can be simplified to directly determine the natural gas density at the present time and the time when the gas reservoir was formed, and then directly estimate the reduction ratio of natural gas density to obtain the total amount of cumulative natural gas loss.

[0113] However, if the purpose of the study is to evaluate the dynamic evolution of the total amount of natural gas loss from the formation of the gas reservoir to the present, since the formation of the gas reservoir lasted for millions of years, the real geological structure has undergone many changes, which will inevitably lead to complex changes in the density of natural gas, and the corresponding natural gas density change curve is not a single increasing or decreasing linear curve. Therefore, in order to clarify the law of the total amount of natural gas loss over geological time, the changes in geological parameters in each small geological time period and the changes in natural gas density caused by the changes in geological parameters should be determined, and then the loss process of the total amount of natural gas loss should be evaluated.

[0114] Furthermore, in this embodiment, the evaluation method further includes step S100: determining geological parameters in different geological time periods. Specifically, determining geological parameters in different geological time periods can be achieved through the following steps:

[0115] Sub-step S1001: Obtain the burial history map, thermal history map and pressure history map of the gas reservoir over the geological evolution time through basin simulation recovery.

[0116] Sub-step S1002: Determine the burial depth of the overlying strata of the gas reservoir at each geological moment and the burial depths d of different lithological strata included in the overlying strata of the gas reservoir based on the burial history diagram. ji and thickness h ji (i=1, 2, 3...n, j=1, 2, 3...).

[0117] Sub-step S1003: Determine the temperature T of the overlying strata of the gas reservoir at each geological moment based on the thermal history map and the pressure history map. ji and pressure P ji (i=1, 2, 3,…n).

[0118] Furthermore, in this embodiment, when the loss amount and loss time of ancient natural gas reservoirs are quantitatively evaluated, different loss times can be determined by combining different geological time periods experienced after the formation of the gas reservoir, and then the total cumulative natural gas loss of the gas reservoir at different loss times, the cumulative natural gas diffusion loss of the gas reservoir, and the cumulative natural gas loss of the gas reservoir in forms other than diffusion are calculated.

[0119] In addition, the implementation environment of this embodiment includes at least one terminal and a server, and the method is executed on the terminal or the server respectively. The terminal and the server can be connected in communication to realize the interactive transmission of information.

[0120] Among them, the terminal can be any electronic product that can interact with the user through one or more methods such as keyboard, touchpad, touch screen, voice interaction, etc., such as PC (Personal Computer), PPC (Pocket Personal Computer), tablet computer, etc.

[0121] The server can be a single server or a server cluster composed of multiple servers. It can also be a cloud server that provides basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communications, middleware services, domain name services, security services, CDN (Content Delivery Network), as well as big data and artificial intelligence platforms.

[0122] Embodiment 2

[0123] Taking a natural gas reservoir in the Sichuan Basin as an example, the second embodiment of the present invention provides a method for evaluating the scattered vector of an ancient natural gas reservoir, the method comprising the following steps:

[0124] Step S201: Restore the burial history of natural gas reservoirs at different geological times using basin simulation technology (e.g. Figure 3 shown).

[0125] Step S202: Set n geological time points t according to different time intervals i (i=1, 2, 3...n), where t1 represents the current time, t n represents the time of gas reservoir formation, [t i , t i+1 ] can represent a geological time period.

[0126] Step S203: Obtain the jth stratum covering the gas reservoir at geological time t according to the burial history map i The corresponding burial depth d ji and thickness h ji (j=1, 2, 3...; i=1, 2, 3...n).

[0127] If the overlying strata of the gas reservoir is a single-layer cap layer model, then j=1; if the overlying strata of the gas reservoir is a multi-layer cap layer model, then j>1, and the overlying strata of the gas reservoir should include multiple cap layers and multiple reservoir layers.

[0128] Step S204: Obtain the gas reservoir at geological time t according to the burial history mapi The corresponding temperature T i and pressure P i , and the jth stratum covering the gas reservoir at geological time t i The corresponding temperature T ji and pressure P ji (j=1, 2, 3...; i=1, 2, 3...n).

[0129] The temperature and pressure data can be corrected according to the temperature and pressure data of the inclusions.

[0130] Step S205: Based on the gas reservoir at geological time t i Corresponding temperature and pressure, using the gas state equation to calculate the geological time t i The corresponding natural gas density in the gas reservoir is ρ i (i=1, 2, 3,…n).

[0131] Step S206: Calculate geological time t i To geological time t i+1 The total amount of natural gas lost from a reservoir during this geological time period.

[0132] Specifically, the total amount of natural gas lost in the gas reservoir in different geological time periods can be calculated according to the above formula (7). The calculation results are shown in Table 1.

[0133] Table 1. Depth, temperature, pressure and loss of natural gas reservoirs in key geological periods

[0134]

[0135] Step S207: The total amount of natural gas lost in the gas reservoir in different geological time periods is added together to obtain the total amount of accumulated natural gas lost in the gas reservoir.

[0136] Combined with the calculation results in Table 1, the total amount of accumulated natural gas loss in the gas reservoir is finally obtained as:

[0137] G c,loss =G loss,1 +G loss,2 +G loss,3 =461+230+1315=2006 (unit: m 3 ).

[0138] Step S208: Calculate geological time t i To geological time t i+1 The amount of natural gas that has diffused through the caprock within the reservoir during this geological time period.

[0139] Specifically, the diffusion amount of natural gas through the cap layer per unit area in different geological time periods can be calculated according to the above formula (8). The parameter values ​​required by formula (8) are detailed in Table 2, and the final calculation of the diffusion amount of natural gas through the cap layer in different geological time periods is detailed in Table 3.

[0140] Table 2 Cap layer parameters required for diffusion calculation

[0141]

[0142] Table 3 Diffusion of natural gas reservoirs through the cap rock at different geological times

[0143]

[0144] Step S209: Add up the diffusion amounts of natural gas through the cap layer per unit area in different geological time periods to obtain the cumulative natural gas diffusion loss amount of the gas reservoir through the overlying strata of the gas reservoir.

[0145] Combined with the calculation results in Table 1, the cumulative natural gas diffusion loss of the gas reservoir formed by diffusion is finally obtained as follows:

[0146] G c,diff =G diff,1 +G diff,2 +G diff,3 =334+594+325=1253 (unit: m 3 ).

[0147] Step S210: Calculate the amount of natural gas lost in the gas reservoir in other ways except diffusion in different geological time periods.

[0148] Specifically, the difference between the total amount of natural gas loss and the amount of natural gas diffusion loss in different geological time periods can be calculated according to the above formula (14), and the other natural gas loss amount G can be preliminarily obtained. other,i Then determine the other natural gas loss amount G in each geological time period. other,i The result of the calculation is less than zero. If G other,i If it is less than zero, then G diff,i Too high, need to adjust the calculation G diff,i The input parameters of c1 are changed from the original uniform value of 0.040 kg CH4 / m 3 Adjusted to 0.125~0.034kg CH4 / m 3 (Table 4), so that G other,i Greater than or equal to zero.

[0149] Finally, by correcting G diff,iThe calculation results of other natural gas loss obtained by the input parameters are shown in Table 5. The corrected cumulative natural gas loss from the gas reservoir formed by diffusion is: G c,diff =292+377+112=781 (unit: m 3 ), the results are shown in Figure 4 .

[0150] Table 4 Bottom c1 of the cap rock at different geological times

[0151]

[0152] Table 5 Other natural gas loss at different geological times before and after correction

[0153]

[0154]

[0155] Step S211: Add up other natural gas losses in different geological time periods to obtain the cumulative natural gas losses of gas reservoirs in forms other than diffusion.

[0156] Combined with the calculation results in Table 5, the cumulative natural gas loss of gas reservoirs in other forms except diffusion is finally obtained as follows:

[0157] G c,other =G other,1 +G other,2 +G other,3 =169+(-147)+1203=1225 (unit: m 3 ).

[0158] The final results of the total amount of gas reservoir cumulative natural gas loss, the cumulative natural gas loss by diffusion, and the cumulative natural gas loss by other forms of gas reservoir except diffusion are shown in Table 6.

[0159] Table 6 Cumulative natural gas loss, diffusion and other forms of natural gas loss

[0160]

[0161] Embodiment 3

[0162] Taking a natural gas reservoir in the Sichuan Basin as an example, the third embodiment of the present invention provides a simplified ancient natural gas reservoir dispersion vector evaluation method, which can quickly calculate the dispersion amount from the formation of the gas reservoir to the present, without requiring the dispersion amount at different geological time intervals, and includes the following steps:

[0163] Step S301: Calculate the total amount of accumulated natural gas loss in the gas reservoir directly through the gas reservoir density at the time of gas reservoir formation and at present.

[0164] Specifically, the calculation formula for the total amount of accumulated natural gas loss in the gas reservoir is:

[0165] Step S302: Simplify the calculation of the cumulative natural gas loss in the gas reservoir where gas loss occurs in the form of diffusion.

[0166] Specifically, the calculation formula for the cumulative natural gas diffusion loss of a gas reservoir where gas loss occurs in the form of diffusion is:

[0167]

[0168]

[0169] Step S303: Calculate the cumulative natural gas loss in gas reservoirs in forms other than diffusion.

[0170] Specifically, the calculation formula for the cumulative natural gas loss from gas reservoirs in other forms except diffusion is:

[0171] G c,other =G c,loss -G c,diff .

[0172] The final results of the total amount of gas reservoir cumulative natural gas loss, the cumulative natural gas loss by diffusion, and the cumulative natural gas loss by other forms of gas reservoir except diffusion are shown in Table 7.

[0173] Table 7 Simplified calculation of cumulative natural gas loss, diffusion and other forms of natural gas loss

[0174]

[0175] By comparing the calculation results of Table 6 and Table 7, it can be seen that the calculation results of the two methods in Example 2 and Example 3 for the total amount of gas reservoir cumulative natural gas loss are consistent, but the calculation results for the cumulative gas reservoir diffusion loss and the cumulative gas reservoir loss in other forms except diffusion are quite different. In other words, without dividing the geological evolution time from the formation of the gas reservoir to the present into sections and directly evaluating the loss from the formation of the gas reservoir to the present, the calculation results can only ensure the total amount of gas reservoir cumulative natural gas loss (G c,loss ) is accurate, but the cumulative natural gas diffusion loss (G c,diff ) and the cumulative natural gas loss from gas reservoirs in other forms except diffusion (G c,other ) is the calculation result before correction, and does not calculate the natural gas diffusion loss (G diff,i ) and other natural gas diffusion (G other,i ) for correction, so the error with the actual situation is large and inaccurate.

[0176] Embodiment 4

[0177] A fourth embodiment of the present invention further provides an electronic device, see Figure 5 The electronic device includes a processor 201 and a memory 202, wherein at least one computer program is stored in the memory, and the at least one computer program is loaded and executed by one or more of the above-mentioned processors to enable the processor to implement the ancient natural gas reservoir loss evaluation method as described above.

[0178] Of course, the electronic device may also have components such as a wired or wireless network interface, a keyboard, and an input / output interface for input and output. The electronic device may also include other components for realizing various functions of the device, which will not be described in detail here.

[0179] The fourth embodiment of the present invention further provides a computer-readable storage medium, in which at least one program code is stored. The program code is loaded and executed by a processor to enable a computer to implement the ancient natural gas reservoir loss evaluation method as described above.

[0180] Optionally, the computer-readable storage medium may be a read-only memory (ROM), a random access memory (RAM), a compact disc (CD-ROM), a magnetic tape, a floppy disk, and an optical disc data storage device. Those skilled in the art may understand that all or part of the steps in the above-mentioned embodiment method can be completed by instructing the relevant hardware through a program, and the program is stored in a storage medium, including several instructions for making a single-chip microcomputer, a chip or a processor execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disc.

[0181] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0182] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0183] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for evaluating the loss of ancient natural gas reservoirs, characterized in that: The evaluation method includes: Divide the geological evolution time from the formation of gas reservoirs to the present into multiple geological time periods; Based on the reduction ratio of natural gas density in different geological time periods, the total amount of natural gas lost in different geological time periods is determined; Determine the amount of natural gas lost from reservoirs by diffusion in different geological time periods; The difference between the total amount of natural gas lost in different geological time periods and the amount of natural gas lost by diffusion is determined as the other amount of natural gas lost in other forms of gas reservoir loss.

2. The method for evaluating the loss of ancient natural gas reservoirs according to claim 1, characterized in that: The evaluation method further comprises: The total amount of natural gas loss in different geological time periods is added up to obtain the total amount of accumulated natural gas loss in the gas reservoir; The amount of natural gas lost by diffusion from the gas reservoir in different geological time periods is added up to obtain the cumulative amount of natural gas lost by diffusion from the gas reservoir through the overlying strata of the gas reservoir; The other natural gas losses from gas reservoirs in other forms during different geological time periods were added together to obtain the cumulative natural gas losses from gas reservoirs in forms other than diffusion.

3. The method for evaluating the loss of ancient natural gas reservoirs according to claim 1, characterized in that: The evaluation method further comprises: Determine whether the difference between the total amount of natural gas loss and the amount of natural gas diffusion loss in each geological time period is less than zero; If the difference is less than zero, adjusting the input parameters for calculating the natural gas diffusion loss to obtain a new natural gas diffusion loss; If the difference is greater than or equal to zero, the difference between the total amount of natural gas lost in the geological time period and the amount of natural gas lost by diffusion is determined as the other amount of natural gas lost from the gas reservoir in other forms.

4. The method for evaluating the loss of ancient natural gas reservoirs according to claim 1, characterized in that: The calculation formula for the total amount of natural gas loss in different geological time periods is: Among them, G loss,i is the time from the i-th geological moment t i To the i+1th geological moment t i+1 Total amount of natural gas loss, m 3 ; G i is the i-th geological moment t i Gas reservoir volume under standard conditions, m 3 ρ i is the i-th geological moment t i The density of natural gas in the gas reservoir, kg / m 3 ρ i+1 is the i+1th geological time t i+1 The density of natural gas in the gas reservoir, kg / m 3 ; i = 1, 2, 3...n, t1 represents the current geological time, t n represents the time of gas reservoir formation, t i represents the i-th geological moment.

5. The method for evaluating the loss of ancient natural gas reservoirs according to claim 1, characterized in that: The determination of the amount of natural gas lost from gas reservoirs in the form of diffusion in different geological time periods includes: Determine the diffusion of natural gas through a unit area of ​​caprock over different geological time periods; Determine the area of ​​gas reservoirs in different geological time periods; Based on the gas reservoir area and the diffusion amount of natural gas through the cap rock per unit area in different geological time periods, the amount of natural gas lost from the gas reservoir in the form of diffusion in different geological time periods is determined.

6. The method for evaluating the loss of ancient natural gas reservoirs according to claim 5, characterized in that: When the overlying stratum of the gas reservoir is a single-layer cap layer, the calculation formula for the diffusion amount of natural gas through the cap layer per unit area in different geological time periods is: Among them, q i is the time from the i-th geological moment t i To the i+1th geological time t i+1 The amount of natural gas diffused through the cap rock per unit area during this geological period, kg / m 2 ;D e is the diffusion coefficient of the saturated water sample, m 2 / s; h is the thickness of the single-layer cap layer, m; c1 is the gas concentration at the interface between the gas and the cap layer, kg / m 3 .

7. The method for evaluating the loss of ancient natural gas reservoirs according to claim 5, characterized in that: When the overlying strata of the gas reservoir are multiple reservoir-caprock combinations, the calculation formula for the diffusion amount of natural gas through the caprock per unit area in different geological time periods is: Among them, q i is the time from the i-th geological moment t i To the i+1th geological time t i+1 The diffusion amount per unit area, kg / m 2 ;D ei is the overlying stratum of the gas reservoir at the i-th geological time t i The comprehensive diffusion coefficient, 10 -10 m 2 / s;h ji is the jth lithologic stratum contained in the overlying strata of the gas reservoir at the i-th geological time t i Thickness, m; j = 1, 2, 3, ...; c 1i is the i-th geological moment t i Gas concentration at the interface between the gas and the direct cap layer, kg / m 3 ; φ i is the i-th geological moment t i The porosity of the sample, %; ρ wi is the i-th geological moment t i Density of formation water, kg / m 3 ; S gi is the i-th geological moment t i Solubility of natural gas in formation water under actual temperature and pressure conditions, mol / kg.

8. The method for evaluating the loss of ancient natural gas reservoirs according to claim 1, characterized in that: The evaluation method further comprises: The total amount of accumulated natural gas loss from the gas reservoir is determined based on the gas reservoir volume and natural gas density in the gas reservoir under standard conditions at the current geological time, as well as the natural gas density in the gas reservoir when the gas reservoir was formed.

9. An electronic device, characterized in that: The electronic device includes a processor and a memory, wherein the memory stores at least one computer program, and the at least one computer program is loaded and executed by one or more of the above processors, so that the processor executes the ancient natural gas reservoir loss evaluation method according to any one of claims 1 to 8.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores at least one program code, and the program code is loaded and executed by a processor to enable a computer to execute the method for evaluating the loss of ancient natural gas reservoirs according to any one of claims 1 to 8.

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