Complex tectonic area shale gas resource quantity calculation method and system

Abstract

The invention discloses a method and a system for calculating shale gas resource quantity in a complex tectonic region, and relates to the field of shale gas.The method comprises the following steps: step 1, performing regional division on shale gas in the complex tectonic region, delineating a prospective region, then preferably selecting a favorable region, and further preferably selecting a target region from the favorable region; the regional division takes geological condition indexes as standards; step 2, acquiring first static information and second static information; 3, calculating the adsorption gas resource quantity, the free gas resource quantity and the dissolved gas resource quantity of the target area; and 4, calculating the final shale gas resource quantity of the target area. The method is mainly used for solving the technical problems that in the prior art, the accuracy of preliminary estimation of the geological reserves of the shale gas reservoir in the complex structure area is low, errors are large, and correction cannot be achieved, and the technical effect of calculating the final recoverable reserves of the shale gas reservoir in the complex structure area is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of shale gas, and particularly relates to a method and system for calculating shale gas resources in complex structural areas. Background Art

[0002] Shale gas is an unconventional natural gas resource, mainly stored in dark mudstones with low porosity and extremely low permeability. A complex structure region is an area that has undergone superimposed transformation of multiple tectonic movements, with strongly folded and deformed strata, uplift, erosion, a developed fault system, complex fold forms, and is affected by geological processes such as magmatic activity and metamorphism. The oil and gas preservation conditions are complex, and the exploration and development are difficult. In complex structural areas, there are significant differences in the geological conditions, reservoir conditions, and burial evolution characteristics of shale gas, which have important impacts on the exploration and development of shale gas. First, the basic geological conditions of shale gas in complex structural areas have typical regional characteristics. Secondly, the reservoir conditions also show obvious differences in complex structural areas. Moreover, the burial evolution characteristics are also different in complex structural areas. Finally, the trap conditions are also important factors affecting the enrichment of shale gas in complex structural areas.

[0003] In complex structural areas, due to the characteristics of shale gas, if the general method for calculating the geological reserves of shale gas reservoirs is used, it will result in low accuracy, large errors, and affect the economic benefit evaluation. Summary of the Invention

[0004] The first aspect of the present invention provides a method for calculating shale gas resources in complex structural areas, including:

[0005] Step 1: Divide the shale gas in the complex structural area into regions, delineate the prospective areas, and then further select the favorable areas from the favorable areas, and then further select the target areas from the favorable areas; the regional division is based on geological condition indicators;

[0006] Step 2: Obtain the first static information and the second static information;

[0007] Step 3: Calculate the adsorbed gas resources, free gas resources, and dissolved gas resources in the target area;

[0008] Step 4: Calculate the final shale gas resources in the target area.

[0009] Specifically, the requirements for the regional division in Step 1 are as follows: The method for delineating the prospective areas is mainly to evaluate whether there is a large-scale organic-rich shale developed; the method for selecting the favorable areas is mainly to evaluate whether there is a certain-scale gas-bearing shale section developed; the method for selecting the target areas is mainly to evaluate whether it has commercial exploitation value on the basis of obtaining shale gas flow.

[0010] Specifically, the geological condition indicators in Step 1 include: basic geological conditions, reservoir conditions, gas-bearing characteristics, and structural preservation conditions.

[0011] Specifically, the first static information in Step 2 includes: shale gas-bearing area, effective thickness of shale gas reservoir, shale mass density, adsorbed gas content of shale gas, effective porosity of shale, gas saturation of shale, shale gas formation volume factor; the second static information includes: original oil in place, solution gas-oil ratio.

[0012] Specifically, for the adsorbed gas resource volume in Step 3, the calculation method is:

[0013] G_X = 0.01A_g hρ_y C_x (1);

[0014] In the formula, G_X is the adsorbed gas resource volume; A_g is the shale gas-bearing area; h is the effective thickness of the shale gas reservoir; ρ_y is the shale mass density; C_x is the adsorbed gas content of shale gas.

[0015] Specifically, for the free gas resource volume in Step 3, the calculation method is:

[0016] G_Y = (0.01A_g hΦS_gi) / B_gi (2);

[0017] In the formula, G_Y is the free gas resource volume; A_g is the shale gas-bearing area; h is the effective thickness of the shale gas reservoir; Φ is the effective porosity of shale; S_gi is the gas saturation of shale; B_gi is the shale gas formation volume factor.

[0018] Specifically, for the solution gas resource volume in Step 3, the calculation method is:

[0019] G_S = 10^(-4)NR_si (3);

[0020] In the formula, G_S is the solution gas resource volume; N is the original oil in place; R_si is the solution gas-oil ratio.

[0021] Specifically, for the final shale gas resource volume in Step 4, when the shale interval does not contain crude oil, the solution gas resource volume is not calculated, and the formula for the final shale gas resource volume is:

[0022] G_Z = G_X + G_Y (4);

[0023] In the formula, G_X is the adsorbed gas resource volume; G_Y is the free gas resource volume; G_Z is the final shale gas resource volume;

[0024] When the shale interval contains crude oil, the solution gas resource volume is calculated, and the formula for the final shale gas resource volume is:

[0025] G_Z = G_X + G_Y + G_S (5);

[0026] Wherein, G_X is the adsorbed gas resource volume; G_Y is the free gas resource volume; G_S is the dissolved gas resource volume; G_Z is the ultimate shale gas resource volume.

[0027] The second aspect of the present invention provides a system for calculating shale gas resource volume in a complex structural area, and the system includes:

[0028] A regional division unit for dividing the shale gas in the complex structural area; after delineating the prospective area, the favorable area is preferably selected, and then the target area is further preferably selected from the favorable area; the regional division is based on geological condition indicators.

[0029] A first data acquisition unit for acquiring first static information.

[0030] A second data acquisition unit for acquiring second static information.

[0031] A first calculation module that uses the first static information to calculate the adsorbed gas resource volume and the free gas resource volume of the target area, and calculates the ultimate shale gas resource volume without considering the dissolved gas resource volume.

[0032] A second calculation module that uses the first static information and the second static information to calculate the adsorbed gas resource volume, the free gas resource volume and the dissolved gas resource volume, and finally calculates the ultimate shale gas resource volume considering the dissolved gas resource volume.

[0033] Specifically, the first static information includes the gas-bearing area of shale gas, the effective thickness of the shale gas reservoir, the shale mass density, the adsorbed gas content of shale gas, the effective porosity of shale, the gas saturation of shale, and the shale gas volume coefficient; the second static information includes the geological reserve of crude oil and the dissolved gas-oil ratio.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows: By partitioning the shale gas, the area with high exploitation value is determined. Then, by calculating the adsorbed gas resource volume and the free gas resource volume of the shale gas in this calculation area and considering the situation of the dissolved gas resource volume, the ultimate shale gas resource volume is calculated, making the calculation of the ultimate shale gas resource volume more accurate. The present invention solves the technical problems of the prior art, such as the rough estimation of the geological reserve of shale gas reservoirs in complex structural areas with low accuracy and large errors that cannot be corrected, and realizes the technical effect of calculating the ultimate recoverable reserve of shale gas reservoirs in complex structural areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments.

[0036] Figure 1 It is a flowchart of the method for calculating shale gas resource volume in a complex structural area of the present invention.

[0037] Figure 2 This is the structural diagram of the shale gas resource volume calculation system in the complex structure area of the present invention. Detailed implementation manners

[0038] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0039] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation of the present invention.

[0040] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations. In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0041] Embodiment 1:

[0042] As Figure 1 shown, this embodiment provides a method for calculating the shale gas resource volume in a complex structure area, including the following steps:

[0043] Step 1: Divide the shale gas in the complex structure area, circle the prospective area, then select the favorable area, and further select the target area from the favorable area; the area division is based on geological condition indicators.

[0044] Step 2: Obtain the first static information and the second static information.

[0045] Step 3: Calculate the adsorbed gas resource volume, free gas resource volume, and dissolved gas resource volume of the target area.

[0046] Step 4: Calculate the final shale gas resource volume of the target area.

[0047] In this embodiment, in step one, the shale gas in the complex structural area is partitioned, and the requirements for area division are as follows: prospective area: whether there is organic-rich shale that develops geological conditions for the formation of large-scale shale gas; favorable target area: whether there is a certain-scale gas-bearing shale interval; exploration target area: whether there is an industrial shale gas flow with commercial exploitation value.

[0048] The specific area division of the shale gas in the complex structural area is determined according to geological condition indicators. As shown in Table 1, the geological condition indicators include: basic geological conditions, reservoir conditions, gas-bearing characteristics, structural preservation conditions, and other indicators.

[0049] Table 1 Geological Condition Indicator Table

[0050]

[0051]

[0052] In step two, the first static information and the second static information are obtained.

[0053] The first static information includes: shale gas-bearing area, effective thickness of the shale gas reservoir, shale mass density, adsorbed gas content of shale gas, effective porosity of shale, gas saturation of shale, and shale gas volume factor.

[0054] The second static information includes: geological reserves of crude oil and solution gas-oil ratio.

[0055] In step three, the adsorbed gas resource volume, free gas resource volume, and dissolved gas resource volume of the target area are calculated.

[0056] The adsorbed gas resource volume is estimated by the volume method, and the calculation formula for the adsorbed gas resource volume is as follows:

[0057] G X = 0.01A g hρ y C x (1);

[0058] In the formula, G X is the adsorbed gas resource volume; A g is the shale gas-bearing area; h is the effective thickness of the shale gas reservoir; ρ y is the shale mass density; C x is the adsorbed gas content of shale gas.

[0059] The free gas resource volume is estimated by the volume method, and the calculation formula for the free gas resource volume is as follows:

[0060]

[0061] In the formula, G Y is the free gas resource volume; Ag is the gas-bearing area of shale gas; h is the effective thickness of the shale gas reservoir; Φ is the effective porosity of the shale; S gi is the gas saturation of the shale; B gi is the volume coefficient of shale gas.

[0062] When the shale section contains crude oil, the volume method is used to calculate the dissolved gas resource volume, and the calculation formula for the dissolved gas resource volume is as follows:

[0063] G S = 10 -4 NR si (3);

[0064] In the formula, G S is the dissolved gas resource volume; N is the geological reserve of crude oil; R si is the dissolved gas-oil ratio.

[0065] The final shale gas resource volume in Step Four:

[0066] When the shale section does not contain crude oil, the dissolved gas reserve is not calculated. At this time, the shale gas resource volume is the sum of the adsorbed gas resource volume and the free gas resource volume, and the calculation method is as follows:

[0067] G Z = G X + G Y (4);

[0068] In the formula, G Z is the total shale gas resource volume.

[0069] When the shale section contains crude oil, the dissolved gas reserve is calculated. At this time, the shale gas resource volume is the sum of the adsorbed gas resource volume, the free gas resource volume and the dissolved gas resource volume, and the calculation method is as follows:

[0070] G Z = G X + G Y + G S (5).

[0071] Embodiment Two:

[0072] As Figure 2 described above, this embodiment provides a shale gas resource calculation system in a complex structural area. The system includes:

[0073] A regional division unit for dividing the shale gas in the complex structural area; after determining the prospective area, the favorable area is selected, and then the target area is further selected from the favorable area; the regional division is based on geological condition indicators.

[0074] A first data acquisition unit for acquiring first static information.

[0075] The first static information includes the shale gas-bearing area, the effective thickness of the shale gas reservoir, the shale mass density, the adsorbed gas content of the shale gas, the effective porosity of the shale, the gas saturation of the shale, and the shale gas volume factor.

[0076] A second data acquisition unit is configured to acquire second static information. The second static information includes the original oil in place and the solution gas-oil ratio.

[0077] A first calculation module uses the first static information to calculate the adsorbed gas resource amount and the free gas resource amount in the target area, and calculates the final shale gas resource amount without considering the solution gas resource amount;

[0078] A second calculation module uses the first static information and the second static information to calculate the adsorbed gas resource amount, the free gas resource amount, and the solution gas resource amount, and finally calculates the final shale gas resource amount considering the solution gas resource amount.

[0079] As described above, the above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. Calculation methods for shale gas resources in complex structural areas, including: Step 1: regionalize shale gas in complex structural areas, identify prospective areas, select favorable areas, and then further select target areas from favorable areas; regional division is based on geological condition indicators; Step 2: Obtain the first static information and the second static information; Step 3, calculating the amount of adsorbed gas resources, free gas resources and dissolved gas resources in the target area; Step 4: Calculate the final shale gas resources in the target area.

2. According to the method for calculating shale gas resources in complex tectonic areas described in claim 1, the regional division requirements in step 1 are specifically as follows: the prospect area delineation method is mainly to evaluate whether there is large-scale organic-rich shale; the favorable area optimization method is mainly to evaluate whether there is a certain scale of gas-bearing shale layer; the target area optimization method is mainly to evaluate whether it has commercial exploitation value based on the shale gas flow.

3. According to the method for calculating shale gas resources in complex structural areas of claim 1, the geological condition indicators in step 1 include: Basic geological conditions, reservoir conditions, gas-bearing characteristics, and structural preservation conditions.

4. According to the method for calculating shale gas resources in complex structural areas according to claim 1, the first static information in step 2 includes: Shale gas-bearing area, effective thickness of shale gas reservoir, shale mass density, shale gas adsorbed gas content, shale effective porosity, shale gas saturation, shale gas volume coefficient; The second static information includes: geological reserves of crude oil and dissolved gas-oil ratio.

5. According to the method for calculating shale gas resources in complex structural areas of claim 1, the adsorbed gas resources in step 3 are calculated as follows: G X =0.01A g hρ y C x (1); In the formula, G X is the amount of adsorbed gas resources; A g is the shale gas-bearing area; h is the effective thickness of the shale gas reservoir; ρ y is the mass density of shale; C x is the adsorbed gas content of shale gas.

6. According to the method for calculating shale gas resources in complex structural areas of claim 1, the free gas resources in step 3 are calculated as follows: In the formula, G Y A is the free gas resources; g is the gas-bearing area of ​​shale gas; h is the effective thickness of shale gas reservoir; Φ is the effective porosity of shale; S gi B is the gas saturation of shale; gi is the shale gas volume coefficient.

7. According to the method for calculating shale gas resources in complex structural areas of claim 1, the dissolved gas resources in step 3 are calculated as follows: G S =10 -4 NR si (3); In the formula, G S is the amount of dissolved gas resources; N is the amount of crude oil in place; R si is the dissolved gas-oil ratio.

8. According to the method for calculating shale gas resources in complex structural areas of claim 1, in step 4, the final shale gas resources are calculated by not calculating the dissolved gas resources when the shale layer does not contain crude oil. The final shale gas resources are calculated by the formula: G Z =G X +G Y (4); In the formula, G X is the amount of adsorbed gas resources; G Y is the free gas resources; GZ is the ultimate shale gas resources; When the shale layer contains crude oil, the dissolved gas resources are calculated, and the final shale gas resource calculation formula is: G Z =G X +G Y +G S (5); In the formula, G X is the amount of adsorbed gas resources; G Y is the free gas resources; G S is the amount of dissolved gas resources; G Z The final shale gas resources.

9. Shale gas resource calculation system in complex structural areas, the system includes: Regional division unit, used to divide shale gas into regions with complex structures; After the prospecting area is delineated, the favorable area is selected, and then the target area is further selected from the favorable area; the regional division is based on the geological condition indicators; A first data acquisition unit, used to acquire first static information; A second data acquisition unit, used to acquire second static information; A first calculation module, using the first static information, calculates the adsorbed gas resources and free gas resources of the target area, and calculates the final shale gas resources without considering the dissolved gas resources; The second calculation module uses the first static information and the second static information to calculate the adsorbed gas resources, free gas resources and dissolved gas resources, and finally calculates the final shale gas resources when the dissolved gas resources are taken into account.

10. According to the shale gas resource calculation system for complex structural areas in claim 9, the first static information includes shale gas gas-bearing area, effective thickness of shale gas reservoir, shale mass density, shale gas adsorbed gas content, shale effective porosity, shale gas saturation, and shale gas volume coefficient; the second static information includes crude oil geological reserves and dissolved gas-oil ratio.

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