Multi-parameter combined fracture comprehensive evaluation method and system

Abstract

The invention belongs to the technical field of oil-gas exploration, and particularly relates to a multi-parameter combined fracture comprehensive evaluation method and system, and the method comprises the steps: S1, determining fracture properties and development characteristics; s2, based on fracture properties and development characteristics thereof, quantitatively evaluating fracture activity on the profile; s3, based on fracture properties and development characteristics thereof, quantitatively evaluating fracture closure on the profile; and S4, in combination with fracture development characteristics, fracture activity and fracture closure on a plane, evaluating the conduction or shielding effect of the fracture in the key reservoir forming period. The system comprises a determination module, a first evaluation module, a second evaluation module and a third evaluation module. The system can achieve the systematic research of the fracture reservoir control effect, and is more suitable for the exploration and deployment of fracture-related oil and gas reservoirs. The problem that reservoir control factors of different fractured oil and gas reservoirs are different can be effectively avoided, and the method is more suitable for basically all fractured related oil and gas reservoir forming researches in China.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas exploration, and particularly relates to a multi-parameter combined fault comprehensive evaluation method and system. Background Art

[0002] Fault oil and gas reservoirs are one of the main types of oil and gas reservoirs in oil and gas basins. According to the theory of fault controlling hydrocarbons, faults not only play a dual role of shielding and transport in oil and gas accumulation, but also run through the entire process of oil and gas generation, migration, accumulation and preservation; and the scale of oil and gas reservoirs is positively correlated with the degree of development of controlled faults.

[0003] Under existing technical conditions, fault evaluation mainly includes quantitative or qualitative evaluation of factors such as fault activity, closure, and conductivity. Existing studies have formed specific methods for evaluating different factors. In summary, they mainly include two aspects: one is to conduct research on the relative position of faults and source rock layers during the main accumulation period and the structural position of faults during the main accumulation period, and use whether the fault has conductivity as the main evaluation index to quickly complete the fault evaluation through semi-quantitative analysis; the second is to evaluate different fault elements such as fault activity and closure according to different structural backgrounds and fault properties, and use the evaluation results to participate in the study of fault control. Among the above methods, the former is highly dependent on the detailed interpretation of faults and the quality of seismic data on which they are based, and there is a problem of ignoring some small faults that cannot be explained by seismic data, resulting in inaccurate fault evaluation. The latter mainly evaluates fault elements, and there is a problem of ignoring oil and gas transportation and migration channels, which may lead to incomplete research on fault control.

[0004] It has been found in long-term field support and oil and gas exploration that the existing technology is relatively lacking in comprehensive evaluation research on faults in the process of fault control and reservoir accumulation. Summary of the invention

[0005] The present invention proposes a multi-parameter combined comprehensive fault evaluation method to solve the problem of unclear role of faults in fault control reservoir research, to achieve systematic evaluation of the control effect of faults on oil and gas accumulation, and at the same time to support oil fields in obtaining more systematic geological basis, provide decision-making support for the optimization of oil and gas exploration targets, and further enhance the ability to optimize targets in fault development areas.

[0006] The technical solution adopted by the present invention is as follows: a multi-parameter combined comprehensive fracture evaluation method, the method comprising the following steps:

[0007] S1. Determine the nature of the fracture and its development characteristics;

[0008] S2. Quantitatively evaluate the fault activity on the profile based on the nature of the fault and its development characteristics;

[0009] S3. Based on the nature of the fault and its development characteristics, quantitatively evaluate the fault closure on the profile;

[0010] S4. Combine the fault development characteristics, fault activity and fault closure on the plane to evaluate the transport or shielding effect of the fault during the critical reservoir formation period.

[0011] Furthermore, the step S1 includes: conducting detailed structural interpretation based on two-dimensional and three-dimensional depth domain seismic data, and determining the nature of the fault and its development characteristics by combining the plane and the section.

[0012] Furthermore, determining the properties and development characteristics of the faults in step S1 includes: determining the properties of the faults on the profile, including normal faults, reverse faults and strike-slip faults; identifying the strata cut by the faults on the profile; combining the faults on the plane and determining the development characteristics of the faults, including their extension direction and extension length.

[0013] Furthermore, step S2 includes: based on the knowledge of the nature of the fault and its development characteristics, quantitatively evaluating the activity of the fault by identifying the growth strata, the strata cut by the fault, calculating the fault growth index and the settlement rate of the upper and lower strata on the profile.

[0014] Furthermore, step S2 includes: comparing the thickness of the upper and lower plates of the fault-cut strata on the profile to determine whether the fault is a growth fault; if it is a non-growth fault, qualitatively evaluating the activity period of the fault through the strata cut by the fault; if it is a growth fault, firstly qualitatively evaluating the activity period of the fault by identifying the growth strata, and then calculating the fault growth index and the settlement rate of the upper and lower plates to quantitatively evaluate the activity intensity of the fault.

[0015] Furthermore, step S3 includes: based on the nature of the fault and its development characteristics, combining the distribution of drilled oil reservoirs, oil and gas discoveries and formation pressure data on the profile, calculating the mudstone smear factor and the effective fault mud-to-ground ratio to quantitatively evaluate the sealing property of the fault.

[0016] Further, the step S3 includes: for areas in which the oil and gas exploration stage is relatively mature, the distribution of drilled oil reservoirs, oil and gas discoveries and formation pressure are comprehensively applied to determine whether the formations of the upper wall and lower wall of the fault belong to the same set of oil and gas reservoirs, and to qualitatively evaluate the sealing property of the fault;

[0017] For areas with few wells, the closure of the fault is quantitatively evaluated by calculating the mudstone smear factor and the effective fault mud-to-ground ratio on the profile.

[0018] Furthermore, step S4 includes: firstly, based on the fault development characteristics on the plane, combined with source rock conditions, known oil reservoir distribution and known oil reservoir analysis, a comprehensive application of geochemical indicators is used to preliminarily determine the fault's conduction or shielding effect on oil and gas accumulation; then, combined with the fault activity and closure, the fault's conduction or shielding effect in the key accumulation period is further determined.

[0019] In addition, the present invention also proposes a multi-parameter combined comprehensive fault evaluation system, the system includes a determination module, a first evaluation module, a second evaluation module and a third evaluation module; wherein,

[0020] The determination module is used to determine the nature of the fracture and its development characteristics;

[0021] The first evaluation module is used to quantitatively evaluate the fault activity on the profile based on the nature of the fault and its development characteristics;

[0022] The second evaluation module is used to quantitatively evaluate the fracture closure on the profile based on the fracture properties and their development characteristics;

[0023] The third evaluation module is used to evaluate the transport or shielding effect of faults in the key reservoir formation period by combining fault development characteristics, fault activity and fault closure on a plane.

[0024] Furthermore, the second evaluation module includes a judgment unit and a calculation unit; wherein the judgment unit is used for comprehensively applying the distribution of drilled oil reservoirs, oil and gas discoveries and formation pressure in areas with relatively mature oil and gas exploration stages to judge whether the upper and lower plate strata of the fault belong to the same set of oil and gas reservoirs, and qualitatively evaluate the closure of the fault; the calculation unit is used for quantitatively evaluating the closure of the fault by calculating the mudstone smear factor and the effective fault mud-to-ground ratio on the profile in areas with fewer wells.

[0025] The present invention further improves the existing fault evaluation data, and the combination of multiple parameters can more effectively carry out systematic evaluation of faults, which has the following advantages: first, it can realize the systematic study of the role of faults in controlling reservoirs, and is more suitable for the exploration and deployment of fault-related oil and gas reservoirs; second, the multi-parameter combined method can effectively avoid the problem that different fault oil and gas reservoirs may have different controlling factors, and is more suitable for basically all fault-related oil and gas accumulation research in China; third, it is simple to operate, has high applicability and timeliness, and can apply the latest research results and geological understanding to the on-site support of oil and gas exploration and production as soon as possible.

[0026] Other features and advantages of the present invention will be described in the following description, and part of them will become obvious from the description, or be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the description and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 Schematic diagram of a multi-parameter combined comprehensive fracture evaluation method according to an embodiment of the present invention;

[0029] Figure 2 It is a schematic diagram of a multi-parameter combined comprehensive fracture evaluation system in an embodiment of the present invention. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] like Figure 1 As shown, a multi-parameter combined comprehensive fracture evaluation method comprises the following steps:

[0032] S1. Determine the nature of the fracture and its development characteristics;

[0033] S2. Quantitatively evaluate the fault activity on the profile based on the nature of the fault and its development characteristics;

[0034] S3. Based on the nature of the fault and its development characteristics, quantitatively evaluate the fault closure on the profile;

[0035] S4. Combine the fault development characteristics, fault activity and fault closure on the plane to evaluate the transport or shielding effect of the fault during the critical reservoir formation period.

[0036] Specifically, step S1 includes: conducting fine structural interpretation based on two-dimensional and three-dimensional depth domain seismic data, especially fault interpretation, preliminarily clarifying the nature and development characteristics of the faults, firstly clarifying the current nature of the faults on the profile, including normal faults, reverse faults, strike-slip faults, etc., and identifying the strata cut by the faults, and secondly, combining the faults on the plane and clarifying the development characteristics of the faults, including their extension direction, extension length, etc.;

[0037] Specifically, step S2 includes: ① judging whether the fault has the characteristics of a growth fault by comparing the thickness of the upper and lower layers of the fault on the profile; ② for non-growth faults, qualitatively evaluating the formation or activity period of the fault through the layers cut by the fault; ③ for growth faults, firstly qualitatively evaluating the activity period of the fault by identifying the growth layers, and then calculating the fault growth index, the settlement rate of the upper and lower layers, etc. to quantitatively evaluate the activity intensity of the fault.

[0038] Specifically, step S3 includes: ① For areas where the oil and gas exploration stage is relatively mature, comprehensively apply the data such as drilling logging, formation pressure and oil and gas discovery to determine whether the upper and lower plate strata of the fault are the same set of oil and gas reservoirs, and preliminarily qualitatively evaluate the closure of the fault; ② For areas where fewer wells have been drilled, quantitatively evaluate the closure of the fault on the profile by calculating the mudstone smear factor, effective fault mud-to-ground ratio, etc.

[0039] Specifically, step S4 includes: ① based on the development characteristics of the faults on the plane, combined with the source rock conditions, the distribution of known oil reservoirs and the analysis of known oil reservoirs, the comprehensive application of geochemical index analysis, etc., to preliminarily qualitatively determine the transport or shielding effect of the faults on oil and gas accumulation; ② combined with the activity evaluation and closure evaluation of the previous faults, further clarify the transport or shielding effect of the faults in the key accumulation period.

[0040] It should be noted that the numbers between the above steps (such as step S2, step S3) do not represent the order of implementation of the steps. They are only used as identifiers to distinguish the steps. There may be an implementation order between step S2 and step S3, such as being implemented in parallel or step S3 before step S2, which does not affect the implementation of the method proposed in the present invention.

[0041] After step S4, in order to verify the specific effect of the multi-parameter combined comprehensive fault evaluation method proposed by the present invention, the transmission or shielding effect of the fault can be verified by using new drilling and oil and gas testing.

[0042] In addition, the present invention also proposes a multi-parameter combined comprehensive fracture evaluation system, such as Figure 2 As shown, the system includes a determination module, a first evaluation module, a second evaluation module and a third evaluation module; wherein the determination module is used to determine the nature of the fault and its development characteristics; the first evaluation module is used to quantitatively evaluate the fault activity on the profile based on the nature of the fault and its development characteristics; the second evaluation module is used to quantitatively evaluate the fault closure on the profile based on the nature of the fault and its development characteristics; the third evaluation module is used to evaluate the conduction or shielding effect of the fault in the key reservoir formation period in a plane by combining the fault development characteristics, fault activity and fault closure.

[0043] Specifically, the second evaluation module includes a judgment unit and a calculation unit; wherein the judgment unit is used for comprehensively applying the distribution of drilled oil reservoirs, oil and gas discoveries and formation pressure in areas with relatively mature oil and gas exploration to judge whether the upper and lower plate strata of the fault belong to the same set of oil and gas reservoirs, and qualitatively evaluate the closure of the fault; the calculation unit is used for quantitatively evaluating the closure of the fault by calculating the mudstone smear factor and the effective fault mud-to-ground ratio on the profile in areas with fewer wells.

[0044] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-parameter combined comprehensive fracture evaluation method, characterized in that: The method comprises the following steps: S1. Determine the nature of the fracture and its development characteristics; S2. Quantitatively evaluate the fault activity on the profile based on the nature of the fault and its development characteristics; S3. Based on the nature of the fault and its development characteristics, quantitatively evaluate the fault closure on the profile; S4. Combine the fault development characteristics, fault activity and fault closure on the plane to evaluate the transport or shielding effect of the fault during the critical reservoir formation period.

2. The method according to claim 1, characterized in that The step S1 comprises: Detailed structural interpretation is carried out based on two-dimensional and three-dimensional depth domain seismic data, and the nature of the fault and its development characteristics are determined by combining plane and section.

3. The method according to claim 2, characterized in that Determining the fracture properties and development characteristics in step S1 includes: Determine the nature of faults on the cross section, including normal faults, reverse faults, and strike-slip faults; At the same time, the strata cut by the fault are identified on the cross section; The fault combinations are carried out on the plane and the fault development characteristics are determined, including their extension direction and extension length.

4. The method according to claim 1, characterized in that: The step S2 comprises: Based on the nature of the fault and its development characteristics, the activity of the fault is quantitatively evaluated on the profile by identifying the growth strata, the strata cut by the fault, and calculating the fault growth index and the settlement rate of the upper and lower wall strata.

5. The method according to claim 4, characterized in that The step S2 comprises: On the section, the thickness of the stratigraphic layers between the upper and lower walls of the fault cutting is compared to determine whether the fault is a growth fault; If it is a non-growth fault, the activity period of the fault can be qualitatively evaluated by the strata cut by the fault; If it is a growth fault, the activity period of the fault is first qualitatively evaluated by identifying the growth strata, and then the activity intensity of the fault is quantitatively evaluated by calculating the fault growth index and the settlement rate of the upper and lower strata.

6. The method according to claim 1, characterized in that The step S3 comprises: Based on the nature of the fault and its development characteristics, the closure of the fault is quantitatively evaluated by combining the distribution of drilled reservoirs, oil and gas discoveries and formation pressure data on the profile, calculating the mudstone smear factor and the effective fault mud-to-ground ratio.

7. The method according to claim 6, characterized in that The step S3 comprises: For areas where oil and gas exploration is relatively mature, the distribution of drilled reservoirs, oil and gas discoveries, and formation pressure are comprehensively applied to determine whether the strata on the upper and lower sides of the fault belong to the same set of oil and gas reservoirs, and to qualitatively evaluate the sealing properties of the fault; For areas with few wells, the closure of the fault is quantitatively evaluated by calculating the mudstone smear factor and the effective fault mud-to-ground ratio on the profile.

8. The method according to claim 1, characterized in that: The step S4 comprises: Firstly, based on the fault development characteristics, combined with source rock conditions, known reservoir distribution and known reservoir analysis, the geochemical index analysis is used to preliminarily determine the role of faults in transporting or blocking oil and gas accumulation. Then, combined with the fault activity and closure, the fault's transport or shielding role during the critical reservoir formation period can be further determined.

9. A multi-parameter combined fracture comprehensive evaluation system, characterized in that: The system comprises a determination module, a first evaluation module, a second evaluation module and a third evaluation module; wherein, The determination module is used to determine the nature of the fracture and its development characteristics; The first evaluation module is used to quantitatively evaluate the fault activity on the profile based on the nature of the fault and its development characteristics; The second evaluation module is used to quantitatively evaluate the fracture closure on the profile based on the fracture properties and their development characteristics; The third evaluation module is used to evaluate the transport or shielding effect of faults in the key reservoir formation period by combining fault development characteristics, fault activity and fault closure on a plane.

10. The system according to claim 9, characterized in that The second evaluation module includes a judgment unit and a calculation unit; wherein, The judgment unit is used to comprehensively apply the distribution of drilled oil reservoirs, oil and gas discoveries and formation pressure in areas with relatively mature oil and gas exploration to judge whether the upper and lower wall strata of the fault belong to the same set of oil and gas reservoirs, and qualitatively evaluate the sealing property of the fault; The calculation unit is used to quantitatively evaluate the sealing property of the fault by calculating the mudstone smear factor and the effective fault mud-to-ground ratio on the profile in the area with few wells drilled.

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