A multi-parameter combined fracture comprehensive evaluation method and system

Abstract

This invention belongs to the field of oil and gas exploration technology, and specifically relates to a multi-parameter combined fracture comprehensive evaluation method and system. The method includes: S1, determining the nature and development characteristics of the fracture; S2, quantitatively evaluating fracture activity on the cross-section based on the fracture nature and development characteristics; S3, quantitatively evaluating fracture sealing on the cross-section based on the fracture nature and development characteristics; and S4, evaluating the conduction or blocking effect of the fracture during key hydrocarbon accumulation periods on the plane, combining fracture development characteristics, fracture activity, and fracture sealing. The system includes a determination module, a first evaluation module, a second evaluation module, and a third evaluation module. This invention enables a systematic study of the fracture-controlled hydrocarbon accumulation effect, and is more suitable for the exploration deployment of fracture-related oil and gas reservoirs; it can effectively avoid the problem of differences in the controlling factors of different fracture oil and gas reservoirs, and is more applicable to almost all fracture-related oil and gas accumulation studies in China.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of oil and gas exploration, and particularly relates to a multi-parameter combined fracture comprehensive evaluation method and system. BACKGROUND

[0002] Fracture oil and gas reservoirs are one of main oil and gas reservoir types in oil and gas basins. According to the fracture-controlled hydrocarbon theory, fractures not only play a double role of shielding and conducting in oil and gas accumulation, but also run through the whole process of oil and gas generation, migration, accumulation and preservation. Moreover, the scale of the oil and gas reservoirs is positively correlated with the development degree of the controlled fractures.

[0003] Under the existing technical conditions, fracture evaluation mainly includes quantitative or qualitative evaluation of fracture activity, sealing property, conducting capacity and other elements. The existing research has formed specific methods for evaluating different elements. In summary, there are two aspects: one is to study the relative position of the main accumulation period fracture and the source rock layer and the structural position of the main accumulation period fracture, to take whether the fracture has conducting capacity as the main evaluation index, and to quickly complete fracture evaluation through semi-quantitative analysis; the other is to evaluate different fracture elements such as fracture activity and sealing property according to different tectonic backgrounds and fracture properties, and to use the evaluation results in fracture-controlled reservoir research. In the above methods, the former is strongly dependent on the quality of seismic data for the fine interpretation of fractures, and there is a problem of ignoring some small faults that cannot be explained by seismic data, which leads to inaccurate fracture evaluation. The latter mainly evaluates fracture elements, and there is a problem of ignoring oil and gas conducting and migration channels, which may lead to imperfect fracture-controlled reservoir research.

[0004] Long-term field support and oil and gas exploration have found that the existing technology is relatively lacking in comprehensive evaluation of fractures in fracture-controlled reservoirs. SUMMARY

[0005] The application proposes a multi-parameter combined fracture comprehensive evaluation method to solve the problem of unclear fracture action in fracture-controlled reservoir research, realize systematic evaluation of the control action of fractures on oil and gas accumulation, support oil fields to obtain more systematic geological basis, provide decision support for oil and gas exploration target optimization, and further improve the target optimization ability in fracture development areas.

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

[0007] S1, determining the fracture property and development characteristics;

[0008] S2, quantitatively evaluating the fracture activity on the profile based on the fracture property and development characteristics;

[0009] S3, quantitatively evaluating the fault sealing property on the profile based on the fault property and its development characteristics;

[0010] S4, evaluating the fault's role of conducting or blocking in the key reservoir forming period on the plane by combining the fault development characteristics, fault activity and fault sealing property.

[0011] Further, the step S1 comprises: carrying out fine structure interpretation based on two-dimensional and three-dimensional depth domain seismic data, and determining the fault property and its development characteristics by combining the plane and profile.

[0012] Further, the step S1 of determining the fault property and development characteristics comprises: determining the fault property on the profile, including normal fault, reverse fault and strike-slip fault; simultaneously identifying the strata cut by the fault on the profile; and carrying out fault combination and determining the fault development characteristics on the plane, including the extension direction and extension length.

[0013] Further, the step S2 comprises: quantitatively evaluating the fault activity on the profile by identifying the growth strata, the strata cut by the fault, calculating the fault growth index and the strata subsidence rate of the hanging wall and footwall based on the fault property and its development characteristics.

[0014] Further, the step S2 comprises: judging whether the fault belongs to growth fault by comparing the thickness of the hanging wall and footwall strata cut by the fault on the profile; if it is a non-growth fault, qualitatively evaluating the fault activity period by the strata cut by the fault; if it is a growth fault, firstly qualitatively evaluating the fault activity period by identifying the growth strata, and secondly quantitatively evaluating the fault activity intensity by calculating the fault growth index and the strata subsidence rate of the hanging wall and footwall.

[0015] Further, the step S3 comprises: quantitatively evaluating the fault sealing property on the profile by combining the reservoir distribution of drilled wells, oil and gas discovery and strata pressure data, calculating the mud smear factor and effective fault mud ratio based on the fault property and its development characteristics.

[0016] Further, the step S3 comprises: for the relatively mature area in the oil and gas exploration stage, qualitatively evaluating the fault sealing property by judging whether the hanging wall and footwall strata belong to the same set of oil and gas reservoirs by comprehensively applying the reservoir distribution of drilled wells, oil and gas discovery and strata pressure.

[0017] For the area with less drilled wells, quantitatively evaluating the fault sealing property by calculating the mud smear factor and effective fault mud ratio on the profile.

[0018] Further, the step S4 comprises: firstly, based on the fracture development characteristics, combined with source rock conditions, known reservoir distribution and known reservoir profiling, comprehensively applying geochemical index analysis to preliminarily determine the fracture conduction or shielding effect on oil and gas reservoir formation; and then, combined with the fracture activity and sealing property, further determining the fracture conduction or shielding effect in the key reservoir formation period.

[0019] In addition, the present application further provides a multi-parameter combined fracture comprehensive evaluation system, which comprises a determination module, a first evaluation module, a second evaluation module and a third evaluation module; wherein,

[0020] The determination module is used for determining the fracture property and development characteristics;

[0021] The first evaluation module is used for quantitatively evaluating the fracture activity on the profile based on the fracture property and development characteristics;

[0022] The second evaluation module is used for quantitatively evaluating the fracture sealing property on the profile based on the fracture property and development characteristics;

[0023] The third evaluation module is used for evaluating the fracture conduction or shielding effect in the key reservoir formation period on the plane combined with the fracture development characteristics, fracture activity and fracture sealing property.

[0024] Further, the second evaluation module comprises a judgment unit and a calculation unit; wherein, the judgment unit is used for, for the relatively mature area in the oil and gas exploration stage, comprehensively applying the drilled well reservoir distribution, oil and gas discovery and formation pressure to judge whether the upper and lower wall rocks of the fracture belong to the same set of oil and gas reservoirs, and qualitatively evaluate the sealing property of the fracture; and the calculation unit is used for, for the area with less drilled wells, quantitatively evaluating the sealing property of the fracture on the profile by calculating the mudstone smearing factor and effective fault mudstone ratio.

[0025] The present application further improves the existing fracture evaluation data, and can more effectively carry out the systematic evaluation of the fracture by combining multiple parameters, and has the following advantages: 1. The systematic research on the fracture control effect can be realized, and it is more suitable for the exploration deployment of the fracture-related oil and gas reservoirs; 2. The multi-parameter combined method can effectively avoid the problem that the control factors of different fracture oil and gas reservoirs may be different, and it is more suitable for the fracture-related oil and gas reservoir research in China; 3. The operation is simple, and it has high applicability and timeliness, and the latest research results and geological knowledge can be applied to the field support of oil and gas exploration production as soon as possible.

[0026] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the present application. The objects and other advantages of the present application can be achieved and obtained by the description and drawings. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings described below are only some embodiments of the present application, and the other drawings can be obtained by those skilled in the art without creative effort on the basis of these drawings.

[0028] Figure 1 A schematic diagram of a multi-parameter joint fracture comprehensive evaluation method in an embodiment of the present application;

[0029] Figure 2 A schematic diagram of a multi-parameter joint fracture comprehensive evaluation system in an embodiment of the present application. DETAILED DESCRIPTION

[0030] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative effort fall within the protection scope of the present application.

[0031] As shown in Figure 1 A multi-parameter joint fracture comprehensive evaluation method, the method comprising the following steps:

[0032] S1, determining fracture properties and development characteristics thereof;

[0033] S2, based on the fracture properties and development characteristics thereof, quantitatively evaluating fracture activity on a profile;

[0034] S3, based on the fracture properties and development characteristics thereof, quantitatively evaluating fracture sealing on a profile;

[0035] S4, in combination with the fracture development characteristics, fracture activity and fracture sealing on a plane, evaluating the fracture in a key reservoir forming period in terms of conduction or shielding.

[0036] Specifically, the step S1 comprises: based on two-dimensional or three-dimensional depth domain seismic data, carrying out fine structure interpretation, in particular, fracture interpretation, preliminarily determining fracture properties and development characteristics thereof, one is to determine the present properties of the fracture on a profile, including normal fault, reverse fault, strike-slip fault, etc., and to identify the strata cut by the fracture, and two is to carry out fracture combination on a plane and determine the development characteristics of the fracture, including the extension direction and extension length thereof.

[0037] Specifically, the step S2 comprises: ① determining whether the fault has growth fault property by cutting the upper and lower disc strata thickness contrast and other methods on the profile; ② for non-growth faults, the formation or activity period of the fault is evaluated qualitatively by the strata cut by the fault; ③ for growth faults, the activity period of the fault is evaluated qualitatively by identifying growth strata and other methods, and the activity strength of the fault is evaluated quantitatively by calculating the fault growth index, the upper and lower disc strata subsidence rate and the like.

[0038] Specifically, the step S3 comprises: ① for the relatively mature areas in the oil and gas exploration stage, the data of drilled well logging, strata pressure and oil and gas discovery are comprehensively applied to determine whether the upper and lower disc strata are the same set of oil and gas reservoirs, and the sealing property of the fault is preliminarily evaluated qualitatively; ② for the areas with less drilled wells, the sealing property of the fault is evaluated quantitatively by calculating the mud smearing factor and the effective fault mud ratio on the profile.

[0039] Specifically, the step S4 comprises: ① based on the fault development characteristics on the plane, the source rock conditions, the known oil reservoir distribution and the known oil reservoir analysis, the fault transport or shielding effect on oil and gas accumulation is preliminarily determined qualitatively by comprehensively applying geochemical index analysis; ② combined with the activity evaluation and the sealing property evaluation of the fault in the previous stage, the transport or shielding effect of the fault in the key accumulation period is further determined.

[0040] It should be noted that the numbers between the above steps (such as step S2 and step S3) do not represent the implementation sequence of each step, which is only used as an identifier to distinguish each step, and the implementation sequence between step S2 and step S3 can exist, for example, parallel or step S3 is implemented before step S2, which does not affect the implementation of the method proposed in the present application.

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

[0042] In addition, the present application also proposes a multi-parameter combined fault comprehensive evaluation system, as shown in Figure 2 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 fault property and the development characteristics thereof; the first evaluation module is used to quantitatively evaluate the fault activity on the profile based on the fault property and the development characteristics thereof; the second evaluation module is used to quantitatively evaluate the fault sealing property on the profile based on the fault property and the development characteristics thereof; and the third evaluation module is used to evaluate the transport or shielding effect of the fault in the key accumulation period on the plane in combination with the fault development characteristics, the fault activity and the fault sealing property.

[0043] Specifically, the second evaluation module comprises a judging unit and a calculating unit; the judging unit is configured to, for a relatively mature area in the oil and gas exploration stage, comprehensively apply drilled well reservoir distribution, oil and gas discovery and formation pressure to determine whether the upper and lower wall rocks of the fault belong to the same set of oil and gas reservoirs, and qualitatively evaluate the sealing property of the fault; and the calculating unit is configured to, for an area with less drilled wells, quantitatively evaluate the sealing property of the fault by calculating a mudstone smearing factor and an effective fault mudstone ratio on a profile.

[0044] Although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that the technical solutions recorded in the foregoing embodiments can be modified, or some of the technical features can be replaced by equivalents, and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A multi-parameter joint fracture comprehensive evaluation method, characterized in that, The method comprises the following steps: S1, determining the fracture property and its development characteristics; S2, quantitatively evaluating the fracture activity on the profile based on the fracture property and its development characteristics; S3, quantitatively evaluating the fracture sealing property on the profile based on the fracture property and its development characteristics; S4, evaluating the fracture conduction or shielding effect in the key reservoir forming period in the plane by combining the fracture development characteristics, the fracture activity and the fracture sealing property; The S1 comprises: carrying out fine structure interpretation based on two-dimensional and three-dimensional depth domain seismic data, and determining the fracture property and its development characteristics by combining the plane and the profile; The S2 comprises: quantitatively evaluating the fracture activity on the profile by identifying the growth stratum, the stratum cut by the fracture, calculating the fracture growth index and the stratum subsidence rate of the upper and lower walls based on the fracture property and its development characteristics; The S3 comprises: quantitatively evaluating the fracture sealing property on the profile by combining the reservoir distribution of the drilled well, the oil and gas discovery and the stratum pressure data, calculating the mud smearing factor and the effective fault mud ratio based on the fracture property and its development characteristics; The S4 comprises: firstly, determining the fracture conduction or shielding effect in the key reservoir forming period in the plane based on the fracture development characteristics, combining the source rock condition, the known reservoir distribution and the known reservoir analysis, and comprehensively applying the geochemical index analysis; then, further determining the fracture conduction or shielding effect in the key reservoir forming period by combining the fracture activity and the sealing property.

2. The method of claim 1, wherein, The step S1 of determining the fracture property and the development characteristics comprises: determining the fracture property on the profile, including normal fault, reverse fault and strike-slip fault; simultaneously, identifying the stratum cut by the fracture on the profile; carrying out fracture combination and determining the fracture development characteristics in the plane, including the extension direction and the extension length.

3. The method of claim 1, wherein, The step S2 comprises: judging whether the fracture belongs to the growth fault by comparing the stratum thickness of the upper wall and the lower wall cut by the fracture on the profile; if it is the non-growth fault, qualitatively evaluating the fracture activity period by the stratum cut by the fracture; if it is the growth fault, firstly, qualitatively evaluating the fracture activity period by identifying the growth stratum, and secondly, quantitatively evaluating the fracture activity intensity by calculating the fracture growth index and the stratum subsidence rate of the upper and lower walls.

4. The method of claim 1, wherein, The step S3 comprises: for the relatively mature area in the oil and gas exploration stage, judging whether the stratum of the upper wall and the lower wall of the fracture belongs to the same set of oil and gas reservoir by comprehensively applying the reservoir distribution of the drilled well, the oil and gas discovery and the stratum pressure, and qualitatively evaluating the fracture sealing property; for the area with less drilled wells, quantitatively evaluating the fracture sealing property by calculating the mud smearing factor and the effective fault mud ratio on the profile.

5. A multi-parameter joint fracture comprehensive evaluation system, characterized in that, The multi-parameter combined fracture comprehensive evaluation method according to claim 1, 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 for determining the fracture property and its development characteristics; the first evaluation module is used for quantitatively evaluating the fracture activity on the profile based on the fracture property and its development characteristics; the second evaluation module is used for quantitatively evaluating the fracture sealing property on the profile based on the fracture property and its development characteristics; the third evaluation module is used for evaluating the fracture conduction or shielding effect in the key reservoir forming period in the plane by combining the fracture development characteristics, the fracture activity and the fracture sealing property. The third evaluation module is used for evaluating the conducting or blocking effect of the fault in a key reservoir forming period in combination with the fault development characteristics, fault activity and fault sealing property on a plane.

6. The system of claim 5, wherein, The second evaluation module comprises a judging unit and a calculating unit. The judging unit is used for judging whether the hanging wall and the foot wall of the fault belong to the same set of oil and gas reservoirs and qualitatively evaluating the sealing property of the fault by comprehensively applying the drilled well reservoir distribution, oil and gas discovery and formation pressure for a relatively mature area in an oil and gas exploration stage. The calculating unit is used for quantitatively evaluating the sealing property of the fault by calculating the mudstone smearing factor and the effective fault mudstone ratio on a profile for a relatively less drilled well area.

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