A method for evaluating the effectiveness of fault-controlled lithologic traps

Abstract

The present invention relates to the technical field of oil and gas exploration, and more specifically, to a method for evaluating the effectiveness of a lithologic trap controlled by a fault, comprising the following steps: S1. Quantifying the amount of structural uplift and the amount of erosion in the source area; S2. Determining the distribution direction and range of the lithologic trap sedimentary body by combining rock and mineral geochemistry and fault patterns, and obtaining the sedimentary volume of the lithologic trap; S3. Comparing the amount of erosion with the sedimentary volume of the lithologic trap, when the amount of erosion is greater than or equal to the sedimentary volume of the lithologic trap, it indicates that there is a material basis for the formation of a large lithologic trap; otherwise, it indicates that the material basis is low; S4. For a material basis for the formation of a large lithologic trap, the boundary of a small layer of lithologic trap is implemented, and it is determined that the type of the lithologic trap belongs to a trap controlled by a fault or a non-following fault; S5. For a trap controlled by a fault, the effectiveness is evaluated. The present invention can reveal the formation conditions of the fault-controlled lithologic trap, identify the distribution and type of effective lithologic traps, and perform effectiveness evaluation.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas exploration, and more specifically, to a method for evaluating the effectiveness of a forward fault-controlled lithologic trap. Background Art

[0002] For areas that have experienced multiple tectonic movements and multi-level and multi-stage development of faults, their strata have been transformed by multiple groups of faults, the fault activity patterns are complex, and the control of faults on lithologic traps is not clearly understood. It is extremely difficult to implement and evaluate effective traps in complex fault areas. The formation of fault-controlled lithologic traps has always been a difficult point in the field of petroleum geology, especially for the forward fault-controlled lithologic traps. In the past, it was believed that the poor effectiveness of the forward fault-controlled lithologic traps made it difficult to form large-scale reservoirs. In the past, the characterization of the forward fault-controlled lithologic traps was mainly based on the qualitative combination of single or two methods such as fault system characterization, fault activity analysis, and fault-sand configuration analysis. And it was mainly applied to structural traps. There was little more detailed research on fault-controlled lithologic traps, and it was difficult to accurately evaluate the effectiveness of the forward fault-controlled lithologic traps. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiency of the prior art that it is difficult to accurately evaluate the effectiveness of the forward fault-controlled lithological traps, and to provide a method for evaluating the effectiveness of the forward fault-controlled lithological traps, which can reveal the formation conditions of the fault-controlled lithological traps, identify the distribution and types of effective lithological traps, and perform effectiveness evaluation.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0005] A method for evaluating the effectiveness of a fault-controlled lithologic trap is provided, comprising the following steps:

[0006] S1. Quantitative tectonic uplift and erosion of provenance areas;

[0007] S2. Determine the distribution direction and range of lithologic trap sediments by combining rock and mineral geochemistry and fault patterns, and obtain the lithologic trap sediment volume;

[0008] S3. comparing the amount of denudation with the sedimentary volume of the lithologic trap; when the amount of denudation is greater than or equal to the sedimentary volume of the lithologic trap, it indicates that there is a material basis for the formation of a large lithologic trap; otherwise, it indicates that the material basis for the development of a large lithologic trap is low;

[0009] S4. For those with the material basis for the formation of large lithologic traps, the boundaries of small-layer lithologic traps shall be determined, and the types of lithologic traps shall be determined as traps controlled by either sequential or non-sequential faults;

[0010] S5. Evaluate the effectiveness of traps controlled by forward faults.

[0011] The present invention is a method for evaluating the effectiveness of lithologic traps controlled by a forward fault. The method uses the amount of denudation and the sedimentary volume of the lithologic trap to determine whether there is a material basis for the formation of a large lithologic trap. For a material basis for the formation of a large lithologic trap, the method determines whether the lithologic trap is a trap controlled by a forward or non-forward fault. Then, the effectiveness of the trap controlled by the forward fault is evaluated. The present invention can reveal the formation conditions of lithologic traps controlled by faults, identify the distribution and types of effective lithologic traps, and provide geological basis and technical support for breakthroughs in this field.

[0012] Furthermore, the step S1 comprises:

[0013] S11. Based on the understanding of regional tectonic evolution, combined with the LA-ICPMS apatite fission track experimental method, the relevant parameters of the parent rock area revealed by drilling in the provenance area are experimentally measured, and the tectonic uplift height and tectonic uplift rate are calculated; among which:

[0014] The structural uplift height H 隆 The calculation formula is:

[0015] H 隆 =V 隆 ×t;

[0016] The uplift rate V 隆 The calculation formula is:

[0017] V 隆 =(T i -T 0 ) / G / t;

[0018] Where, T i represents the closing temperature, T 0 represents the surface temperature, G represents the paleo-geothermal gradient, and t represents the fission track age;

[0019] S12. Take typical structural survey lines in different directions of the provenance area and combine them with the balanced profile technology to restore the uplift-subsidence dynamic evolution process of the provenance area and calculate the erosion thickness of the provenance area; wherein the erosion thickness H i The calculation formula is:

[0020] H i =H 隆 -(H 1 -H 2 );

[0021] In the formula, H 1 Indicates the depth of the drilling formation, H 2 represents the depth of the unconformity;

[0022] S13. Determine the denudation area by using 3D seismic data above the sedimentary stratum boundary in the study area, and then calculate the amount of denudation; wherein the amount of denudation V 剥 The calculation formula is:

[0023] V 剥 =H i ×S i ;

[0024] In the formula, S i Indicates the area of ​​erosion.

[0025] Furthermore, in step S11, the calculation formula of the fission track age t is:

[0026]

[0027] In the formula, λD represents 238 The total decay constant of U, ξ represents the correction factor, ρ s represents the spontaneous track density, Cu represents the LA-ICPMS apatite fission track density. 238 U concentration;

[0028] The calculation formula of the paleo-geothermal gradient G is:

[0029] G=(T i -T 0 ) / H 1 ×100;

[0030] Where, T i represents the closing temperature, T 0 represents the surface temperature, H 1 Indicates the depth of the drilling formation.

[0031] Furthermore, the step S2 comprises:

[0032] S21. Interpret 3D seismic data in the study area, conduct regional interpretation of fault systems and sedimentary strata, and identify regional fault systems;

[0033] S22. Compare the fault scale, spatial morphology and stratigraphic thickness of the upthrust and downthrust walls of the identified regional fault system to clarify whether the main sedimentary faults in the fault system have a significant controlling effect on the distribution of sedimentary strata;

[0034] S23. For those with obvious control effects, identify the main source injection area that controls source injection and the conversion slope or fault zone that controls the transportation of debris materials;

[0035] S24. Under the determination of the injection area of ​​the main source and the conversion slope or fault zone, based on the drilling revealed sedimentary strata or parent rock strata and zircon age spectrum, heavy mineral combination of sedimentary strata, rock composition, and comparison of sedimentary strata and parent rock strata characteristics, clarify the main transportation and distribution direction of the clastic material entering each conversion slope or fault zone along the injection area of ​​the main source;

[0036] S25. According to the transportation and distribution direction of the main body of the clastic material, the method of "following the terrain, removing faults, and strong attribute introduction" is adopted to confirm the sedimentary body, restore the distribution of the sedimentary body, and determine the sedimentary volume of the lithological trap.

[0037] Further, in step S22, the comparison method includes:

[0038] If the thickness of the strata on the downthrown side of the fault is greater than that on the upthrown side of the fault, that is, H 下 >H 上 , it means that the corresponding fault is the main fault controlling the sedimentary strata, and the fault during the sedimentary period has a significant controlling effect on the distribution of sedimentary strata;

[0039] If the thickness of the strata on the downthrown side of the fault is less than or equal to the thickness of the strata on the upthrown side of the fault, that is, H 下 ≤H 上 , it means that the corresponding fault was formed after the sedimentary strata were deposited, and the fault during the sedimentary period did not control the distribution of the sedimentary strata;

[0040] In step S23, the method for identifying the main source injection area includes: comparing the paleo-drop and fault activity rate at different locations of the fault, and considering the area with relatively low paleo-drop and relatively low fault activity rate as the main source injection area; wherein:

[0041] The calculation formula of the ancient drop △H is:

[0042] △H=H 下 -H 上 ;

[0043] The fault activity rate V 活 The calculation formula is:

[0044] V 活 =△H / △t 沉 ;

[0045] In the formula, H 下 represents the thickness of the fault downthrown plate, H 上 represents the thickness of the fault uplift plate, △t 沉 Indicates the deposition time of the corresponding stratum.

[0046] Further, in step S25, according to the transportation and distribution direction of the main body of clastic material, along the terrain from high to low, avoiding the sedimentation-controlling faults, maintaining the continuity of the sedimentary body along the strong amplitude area, reconstructing the appearance of the original seismic phase axis, identifying the characteristics of the foreset downlap and the two-way downlap, restoring the morphology of the sedimentary body during the sedimentary period, determining the distribution range of the sedimentary body, and determining the sedimentary volume of the lithological trap; wherein, the sedimentary volume of the lithological trap V 沉 The calculation formula is:

[0047] V 沉 =S 沉 ×(H 沉底 -H 沉顶 );

[0048] In the formula, S 沉 represents the sediment area, H 沉底 Denotes the depth of the sedimentary body, H 沉顶 Indicates the depth of the top of the sediment body.

[0049] Further, step S4 includes:

[0050] S41. Combine the sea level rise and fall curves of the target layer in the study area with the relative sea level changes determined by the rock and paleontological fossil combination revealed by key drilling, and establish a high-precision sequence stratigraphic framework for the target layer in the study area by combining well and seismic data, identify the initial flooding surface and the maximum flooding surface, divide the low-stand system domain, the transgressive system domain, and the high-stand system domain, make fine comparisons of small layers in each system domain, divide small-layer sand groups, and interpret the single-layer sand group stratigraphy and faults in the confirmed sedimentary bodies;

[0051] S42. Based on the interpretation of single-layer sand group strata and corresponding sand group faults, the fault activity of each small-layer sand group controlling sedimentary faults is analyzed, and the activities of each lateral point of the controlling sedimentary faults are compared. The relatively weak activity area is taken as the main source injection port of the corresponding small-layer sand group, and the thickness distribution of the small-layer sand group is analyzed. The micro-paleomorphology is restored based on its thickness change. The geophysical attribute distribution of each small-layer sand group is determined by superimposing and extracting the characteristics of sand and mudstone in combination with the rock physical characteristics, and the lobe distribution characteristics of different sand groups are identified, and the corresponding lithological trap boundaries are determined;

[0052] S43. For each sub-layer, the confirmed lithologic trap boundary is determined based on the change in seismic amplitude energy, lobe distribution characteristics, and changes in physical properties of the drilled wells to determine whether the lithologic trap is a trap controlled by a consequent fault or a trap controlled by a non-continuous fault.

[0053] Furthermore, the step S5 comprises:

[0054] S51. Determine the main period of oil and gas accumulation; among which:

[0055] S511. If there is an oil and gas layer revealed by drilling in the sedimentary strata in the study area, then execute step S512, otherwise execute step S513;

[0056] S512. Determine the main period of oil and gas accumulation by combining forward modeling of hydrocarbon generation and expulsion of source rocks with analysis of fluid inclusions and burial history;

[0057] S513. Determine the main period of oil and gas accumulation by combining forward modeling of hydrocarbon generation and expulsion of source rocks with activity analysis of faults controlling transport and faults controlling the circle;

[0058] S52. Determine whether the trap-controlling fault is active after the main reservoir-forming period. If it is basically inactive, it is considered that the trap is effective. Otherwise, execute step S53;

[0059] S53. If a fault nose trap is formed in the bending section of the controlling fault, the effectiveness of the trap is considered to be good; if the controlling fault forms a single fault block trap by pure tension, the effectiveness of the trap is considered to be poor.

[0060] Further, the step S52 includes: judging whether the trap-controlling fault is active after the main reservoir-forming period, if it is basically inactive, it is considered that the trap is effective, and it is considered that it can form reservoirs and has a certain reservoir-forming scale, otherwise, step S54 is executed;

[0061] The step S5 also includes step S54: for traps with good or poor effectiveness, predicting the scale of natural gas accumulation in different fault activity zones in the traps controlled by the forward faults.

[0062] Furthermore, the step S54 includes the following steps:

[0063] S541. For the structural area revealed by drilling, obtain the gas column height distribution, and obtain multiple gas column height evaluation threshold ranges according to different research areas;

[0064] S542. Statistically analyze the fault activity rate, fault cover ratio, and effective thickness of fault contact in the structural areas with reservoir formation and those without reservoir formation in the structural areas revealed by drilling under similar hydrocarbon source conditions, and use them as prediction parameters to be evaluated;

[0065] S543. Perform linear regression on the three prediction parameters to be evaluated in step S542 and the corresponding air column heights in step S541, and then select the prediction parameter to be evaluated with the best correlation with the air column height as the evaluation prediction parameter; for the evaluation prediction parameter, obtain the corresponding multiple evaluation prediction parameter threshold ranges according to the multiple air column height evaluation threshold ranges in step S541;

[0066] S544. For the structural areas revealed by drilling, the reservoir scale is predicted by the gas column height evaluation threshold range to which the gas column height at the current position belongs; for the structural areas not revealed by drilling, the corresponding evaluation prediction parameters are obtained, and the reservoir scale is predicted by the evaluation prediction parameter threshold range to which the evaluation prediction parameters at the current position belong.

[0067] Compared with the prior art, the present invention has the following beneficial effects:

[0068] 1. The present invention uses the amount of denudation and the sedimentary volume of the lithologic trap to judge whether there is a material basis for the formation of a large lithologic trap, and for those with a material basis for the formation of a large lithologic trap, determines whether the type of the lithologic trap is a trap controlled by a contiguous or non-contiguous fault; then, the effectiveness of the trap controlled by the contiguous fault is evaluated;

[0069] 2. Based on the effectiveness evaluation of the trap, the present invention further predicts the scale of natural gas accumulation in different fault activity zones in the trap controlled by the forward fault. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Figure 1 It is a flow chart of a method for evaluating the effectiveness of a forward fault-controlled lithologic trap according to the present invention;

[0071] Figure 2 This is a schematic diagram of the effective thickness of the fault contact of the present invention;

[0072] Figure 3 This is the natural gas reservoir configuration diagram of Yongle 10 area in the southern part of Baodao Sag of the present invention;

[0073] Figure 4 This is a relationship diagram between the fault activities in the structural zone and the gas column height revealed by the drilling in the Baodao Depression and its surrounding area of ​​the present invention. DETAILED DESCRIPTION

[0074] The present invention is further described below in conjunction with specific implementation methods. In order to enable those skilled in the art to better understand the solution of the present invention, the technical solution in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment 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 the field without creative work should fall within the scope of protection of the present invention.

[0075] Those skilled in the art will appreciate that the embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects.

[0076] It should be noted that the terms "including" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or apparatuses.

[0077] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0078] Embodiment 1

[0079] like Figure 1 The first embodiment of the method for evaluating the effectiveness of a fault-controlled lithologic trap according to the present invention is shown, and includes the following steps:

[0080] S1. Quantitative tectonic uplift and provenance erosion;

[0081] S2. Determine the distribution direction and range of lithologic trap sediments by combining rock and mineral geochemistry and fault patterns, and obtain the lithologic trap sediment volume;

[0082] S3. Compare the amount of denudation with the sedimentary volume of the lithologic trap. When the amount of denudation is greater than or equal to the sedimentary volume of the lithologic trap, it indicates that there is a material basis for the formation of a large lithologic trap; otherwise, it indicates that the material basis for the development of a large lithologic trap is low.

[0083] S4. For those with the material basis for the formation of large lithologic traps, the boundaries of small-layer lithologic traps shall be determined, and the types of lithologic traps shall be determined as traps controlled by either sequential or non-sequential faults;

[0084] S5. Evaluate the effectiveness of traps controlled by forward faults.

[0085] The present invention uses the amount of denudation and the volume of lithologic trap deposition to judge whether there is a material basis for the formation of a large lithologic trap, and for those with a material basis for the formation of a large lithologic trap, determines whether the type of lithologic trap is a trap controlled by a contiguous or non-contiguous fault; then, the effectiveness of the trap controlled by a contiguous fault is evaluated. The present invention can reveal the formation conditions of fault-controlled lithologic traps, identify the distribution and types of effective lithologic traps, and provide geological basis and technical support for breakthroughs in this field.

[0086] Embodiment 2

[0087] This embodiment is a second embodiment of a method for evaluating the effectiveness of a forward fault-controlled lithologic trap according to the present invention. This embodiment is similar to the first embodiment, except that:

[0088] Specifically, step S1 includes:

[0089] S11. Based on the understanding of regional tectonic evolution, combined with the LA-ICPMS apatite fission track experimental method, the relevant parameters of the parent rock area revealed by drilling in the source area were experimentally measured, among which the relevant parameters include closure temperature, surface temperature, 238 The total decay constant of U, the spontaneous track density, 238 U concentration, correction coefficient; then calculate the tectonic uplift height and tectonic uplift rate; where:

[0090] Tectonic uplift height H 隆 The calculation formula is:

[0091] H 隆 =V 隆 ×t;

[0092] Uplift rate V 隆 The calculation formula is:

[0093] V 隆 =(T i -T 0 ) / G / t;

[0094] The calculation formula of fission track age t is:

[0095]

[0096] The calculation formula of paleo-geothermal gradient G is:

[0097] G=(T i -T 0 ) / H 1 ×100;

[0098] Where, T i represents the closing temperature, T 0 represents the surface temperature, G represents the paleo-geothermal gradient, t represents the fission track age; λD represents 238 The total decay constant of U, ξ represents the correction factor, ρ s represents the spontaneous track density, Cu represents the LA-ICPMS apatite fission track density. 238 U concentration;

[0099] S12. Take typical structural survey lines in different directions of the provenance area and combine them with the balanced profile technology to restore the uplift-subsidence dynamic evolution process of the provenance area and calculate the erosion thickness of the provenance area; where the erosion thickness H i The calculation formula is:

[0100] H i =H隆 -(H 1 -H 2 );

[0101] In the formula, H 1 Indicates the depth of the drilling formation, H 2 represents the depth of the unconformity surface. It should be noted that H 1 and H 2 All can be read based on 3D seismic data;

[0102] S13. Determine the denudation area by using 3D seismic data above the sedimentary stratum boundary in the study area, and then calculate the denudation amount; where the denudation amount V 剥 The calculation formula is:

[0103] V 剥 =H i ×S i ;

[0104] In the formula, S i Indicates the area of ​​erosion.

[0105] Specifically, step S2 includes:

[0106] S21. Interpret 3D seismic data in the study area, conduct regional interpretation of fault systems and sedimentary strata, and identify regional fault systems;

[0107] S22. Compare the fault scale, spatial morphology and stratigraphic thickness of the upthrust and downthrust walls of the identified regional fault system to clarify whether the main sedimentary faults in the fault system have a significant controlling effect on the distribution of sedimentary strata;

[0108] Among them, the comparison methods include:

[0109] If the thickness of the strata on the downthrown side of the fault is greater than that on the upthrown side of the fault, that is, H 下 >H 上 , it means that the corresponding fault is the main fault controlling the sedimentary strata. The fault during the sedimentary period has a significant controlling effect on the distribution of the sedimentary strata and can control its lateral distribution and extension;

[0110] If the thickness of the strata on the downthrown side of the fault is less than or equal to the thickness of the strata on the upthrown side of the fault, that is, H 下 ≤H 上 , it means that the corresponding fault was formed after the sedimentary strata were deposited, and the fault during the sedimentary period did not control the distribution of the sedimentary strata;

[0111] S23. For those with obvious control effects, identify the main source injection area that controls source injection and the conversion slope or fault zone that controls the transportation of debris materials;

[0112] It should be noted that the area sandwiched between the two sedimentation-controlling faults is a conversion slope or fault step zone that controls the transport of clastic materials; the relatively weak areas of each sedimentation-controlling fault activity correspond to the fault conversion zone, which is the main source injection area of ​​each fault step; among them:

[0113] The identification method of the main source injection area includes: comparing the paleo-throw and fault activity rate at different locations of the fault, and considering the area with relatively low paleo-throw and relatively low fault activity rate as the main source injection area; among which:

[0114] The calculation formula of the ancient drop △H is:

[0115] △H=H 下 -H 上 ;

[0116] Fault activity rate V 活 The calculation formula is:

[0117] V 活 =△H / △t 沉 ;

[0118] In the formula, H 下 represents the thickness of the fault downthrown plate, H 上 represents the thickness of the fault uplift plate, △t 沉 Indicates the deposition time of the corresponding stratum;

[0119] S24. With the main provenance injection area and the conversion slope or fault zone determined, based on the drilling revealed sedimentary strata or parent rock strata and zircon age spectrum, sedimentary strata heavy mineral assemblage, rock components, and comparison of sedimentary strata and parent rock strata characteristics, clarify the main transportation and distribution direction of clastic materials entering each conversion slope or fault zone along the main provenance injection area; where:

[0120] By investigating the parent rock area of ​​the study area or analyzing the heavy minerals, zircon age spectrum and rock components of the parent rock area and sedimentary strata, comparing the stratigraphic characteristics of the sedimentary strata with those of the parent rock area, the sedimentary strata area with similar parameter combination characteristics to the parent rock area is judged to be affected by the source of the corresponding parent rock area, and the main transportation and distribution directions are determined through the lateral changes of heavy minerals and rock components in the sedimentary strata, such as the increase in the relative content of stable components and the decrease in the relative content of unstable components in the rock components and heavy minerals as the transportation distance is longer, combined with the change in the thickness of the sedimentary strata, combined with the change in the thickness of the sedimentary strata; when the rock components in the parent rock area cannot be analyzed due to sample and data limitations, the similarity of the sedimentary strata components can be compared, and the similar combination areas are considered to be supplied by the same parent rock area, and the main transportation and distribution directions are determined based on the change characteristics of the relative content of the corresponding stable components and unstable components increasing and decreasing with the transportation distance, combined with the change in the thickness of the sedimentary strata. At the same time, the rock properties of the parent rock area can also be judged based on the combination characteristics of the sedimentary strata components. For example, if the heavy mineral content of leukotanilide is high, it indicates that the parent rock is a sedimentary rock; if the heavy mineral content of magnetite is high, it corresponds to an igneous rock parent rock. Under the same parent rock area, as the relative content of leukotanilide increases, the transportation distance increases;

[0121] S25. According to the transportation and distribution direction of the main body of clastic material, the method of "following the terrain, removing faults, and introducing layers with strong attributes" is used to confirm the sedimentary body, restore the distribution of the sedimentary body, and determine the sedimentary volume of the lithological trap; among which:

[0122] According to the transportation and distribution direction of the main body of clastic material, along the terrain from high to low, avoiding the sedimentary faults, maintaining the continuity of the sedimentary body along the strong amplitude area, reconstructing the appearance of the original seismic phase axis, identifying the characteristics of progradational downlap and bidirectional downlap, restoring the morphology of the sedimentary body during the sedimentary period, determining the distribution range of the sedimentary body, and determining the sedimentary volume of the lithological trap; among them, the sedimentary volume of the lithological trap V 沉 The calculation formula is:

[0123] V 沉 =S 沉 ×(H 沉底 -H 沉顶 );

[0124] In the formula, S 沉 It represents the area of ​​sedimentary body, which can be obtained by measuring the distribution range of sedimentary body in 3D seismic data; H 沉底 Denotes the depth of the sedimentary body, H 沉顶 Indicates the depth of the top of the sediment body.

[0125] Specifically, step S3 includes:

[0126] When V 剥 ≥V 沉When the sand content of the lithologic trap sediments is predicted to be high, the sand content is greater than 50%, indicating that there is a material basis for the formation of large lithologic traps;

[0127] When V 剥 <V 沉 When the sand content of the lithologic trap sediments is predicted to be low, the sand content is less than or equal to 50%, indicating that the material basis for the development of large lithologic traps is low.

[0128] Specifically, step S4 includes:

[0129] S41. Combine the sea level rise and fall curves of the target layer in the study area with the relative sea level changes determined by the rock and paleontological fossil combination revealed by key drilling, and establish a high-precision sequence stratigraphic framework for the target layer in the study area by combining well and seismic data, identify the initial flooding surface and the maximum flooding surface, divide the low-stand system domain, the transgressive system domain, and the high-stand system domain, make fine comparisons of small layers in each system domain, divide small-layer sand groups, and interpret the single-layer sand group stratigraphy and faults in the confirmed sedimentary bodies;

[0130] S42. Based on the interpretation of single-layer sand group strata and corresponding sand group faults, the fault activity analysis is conducted for each small-layer sand group controlling sedimentary faults, and the activities of each lateral point of the controlling sedimentary faults are compared. The relatively weak activity area is taken as the main source injection port of the corresponding small-layer sand group, and the thickness distribution analysis of the small-layer sand group is conducted. The micro-paleomorphology is restored based on its thickness change. The geophysical attribute distribution of each small-layer sand group is determined by superimposing and extracting the characteristics of sand and mudstone in combination with the rock physical characteristics. For example, the underwater distributary channel sand has medium-strong amplitude low impedance characteristics, and the distributary bay mudstone has weak amplitude high impedance characteristics. The forward and inversion analysis is used to identify the distribution characteristics of the lobes of different sand groups based on the boundaries of the underwater distributary channel, and the corresponding lithological closure boundaries are determined;

[0131] S43. For each sub-layer, the confirmed lithologic trap boundary is determined based on the change of seismic amplitude energy, the distribution characteristics of the lobes, and the change of physical properties of the drilled wells to determine whether the lithologic trap is a trap controlled by a contiguous fault or a trap controlled by a non-contiguous fault; wherein:

[0132] When the amplitude energy of the delta lobe is relatively stable, the lobe is widely distributed, the drilled reservoirs are all effective reservoirs, and the sand bodies are connected with the main controlling sequential fault, it is considered to be a trap controlled by the sequential fault;

[0133] When the amplitude energy of the delta lobe changes significantly, the lobe migrates frequently, the drilled reservoir has both effective and ineffective reservoirs, and the sand body is separated by lithological or physical phase changes, it is considered to be a trap controlled by non-conformal faults.

[0134] It should be noted that an effective reservoir refers to a reservoir whose physical property is greater than the lower limit of the reservoir physical property, and an ineffective reservoir refers to a reservoir whose physical property is less than the lower limit of the reservoir physical property.

[0135] Specifically, step S5 includes:

[0136] S51. Determine the main period of oil and gas accumulation; among which:

[0137] S511. If there is an oil and gas layer revealed by drilling in the sedimentary strata in the study area, then execute step S512, otherwise execute step S513;

[0138] S512. Determine the main period of oil and gas accumulation by combining forward modeling of hydrocarbon generation and expulsion of source rocks with analysis of fluid inclusions and burial history;

[0139] Combined with forward modeling under the stratigraphic conditions of source rock in the basin, the hydrocarbon generation and expulsion evolution curve of source rock is restored, and its large-scale hydrocarbon generation and expulsion stage is determined as the main hydrocarbon generation peak; the homogenization temperature method of fluid inclusions is used to project the homogenization temperature of salt water inclusions associated with hydrocarbons onto the burial history map to read the oil and gas accumulation time; the common interval of the main hydrocarbon generation peak of source rock and the accumulation time recorded by fluid inclusions is comprehensively determined as the main oil and gas accumulation period;

[0140] S513. Determine the main period of oil and gas accumulation by combining forward modeling of hydrocarbon generation and expulsion of source rocks with activity analysis of faults controlling transport and faults controlling the circle;

[0141] Among them: Combined with the forward simulation under the stratigraphic conditions of the source rock in the basin, the hydrocarbon generation and expulsion evolution curve of the source rock is restored, and its large-scale hydrocarbon generation and expulsion stage is determined as the main hydrocarbon generation peak; the activity rates of the control-transportation faults and the control-circle faults are counted, and the activity time of the control-transportation faults and the control-circle faults are clarified. The formation time of the trap is determined according to the period when the control-circle faults are relatively weak or inactive; the peak interval of hydrocarbon generation and expulsion of the source rock after the trap formation period, the period of strong activity of the control-transportation faults, and the period of weak activity of the control-circle faults are determined as the main oil and gas accumulation period;

[0142] S52. Determine whether the controlling fault is active after the main reservoir formation period. If it is basically inactive, that is, the fault activity rate is less than 10m / Ma, it is considered that the trap is effective; otherwise, it is considered that the controlling fault is still active after the main reservoir formation period, and execute step S53;

[0143] S53. If a fault nose trap is formed in the bending section of the controlling fault, the effectiveness of the trap is considered to be good; if the controlling fault forms a single fault block trap by pure tension, the effectiveness of the trap is considered to be poor.

[0144] Embodiment 3

[0145] This embodiment is a third embodiment of a method for evaluating the effectiveness of a forward fault-controlled lithologic trap according to the present invention. This embodiment is similar to the first or second embodiment, except that:

[0146] Step S52 includes: judging whether the trap-controlling fault is active after the main reservoir-forming period. If it is basically inactive, that is, the fault activity rate is less than 10m / Ma, it is considered that the trap is effective and can form reservoirs with a certain reservoir-forming scale. Otherwise, step S54 is executed.

[0147] Step S5 also includes step S54: predicting the scale of natural gas accumulation in different fault activity zones in the trap controlled by the forward fault.

[0148] Wherein, step S54 includes the following steps:

[0149] S541. For the structural area revealed by drilling, obtain the gas column height distribution, and obtain multiple gas column height evaluation threshold ranges according to different research areas;

[0150] S542. Count the fault activity rate, fault cover ratio, and effective thickness of fault contact in the structural area with reservoir formation and the structural area without reservoir formation in the structural area revealed by drilling under similar hydrocarbon source conditions, and use them as the prediction parameters to be evaluated; it should be noted that similar hydrocarbon source conditions refer to a hydrocarbon generation sag or a hydrocarbon generation sag with similar geological conditions of hydrocarbon source rock formations;

[0151] S543. Perform linear regression on the three prediction parameters to be evaluated in step S542 and the corresponding air column heights in step S541, and then select the prediction parameter to be evaluated with the best correlation with the air column height as the evaluation prediction parameter;

[0152] It should be noted that since the gas column height in the un-accumulated structural area is 0, a linear regression is performed between the gas column height in the accumulated structural area and the corresponding prediction parameter to be evaluated, and the linear regression relationship between the gas column height and the fault activity rate, the linear regression relationship between the gas column height and the fault cover ratio, and the linear regression relationship between the gas column height and the effective thickness of the fault contact are obtained; then, the one with the best correlation with the gas column height is selected as the evaluation prediction parameter;

[0153] For the evaluation prediction parameter, according to the multiple gas column height evaluation threshold ranges in step S541, the corresponding multiple evaluation prediction parameter threshold ranges can be obtained in the linear regression relationship;

[0154] S544. For the structural area revealed by drilling, the accumulation scale is predicted by the gas column height evaluation threshold range to which the gas column height at the current position belongs; for the structural area not revealed by drilling, the corresponding evaluation prediction parameters are obtained, and the accumulation scale is predicted by the evaluation prediction parameter threshold range to which the evaluation prediction parameters at the current position belong. In other words, for the structural area not revealed by drilling, the accumulation scale can be predicted by the gas column height corresponding to the evaluation prediction parameters in the corresponding linear regression relationship.

[0155] That is, for the structural area revealed by drilling, it is believed that the greater the gas column height, the more favorable it is for natural gas accumulation; therefore, it can be considered that when the selected evaluation prediction parameter is the fault activity rate, in the structural area with accumulation, the smaller the fault activity rate, the more favorable it is for natural gas accumulation. In the structural area without accumulation, since the gas column height is 0, it is believed that the greater the fault activity rate, the worse the trap preservation conditions, the worse the trap effectiveness, and the more difficult it is for the trap to accumulate.

[0156] That is, for structural areas that have not been revealed by drilling, the reservoir scale is predicted based on the evaluation prediction parameter threshold range of the corresponding evaluation prediction parameters, or based on the gas column height evaluation threshold range of the gas column height corresponding to the corresponding evaluation prediction parameters in the linear regression relationship.

[0157] When the effectiveness evaluation method of the lithologic trap controlled by the forward fault of the present invention is applied to the southern area of ​​the Baodao Sag, the lithologic trap area controlled by the forward fault is identified. The area is facing the parent rock area of ​​the Songnan low uplift, which is small in area and controlled by multi-level forward faults. The early drilling revealed the characteristics of high-mature coal-type gas and methane inclusions, which confirmed the active migration of oil and gas. However, the gas logging anomaly was not obvious and was interpreted as a water layer. Analysis showed that the main reason for its failure was the effectiveness of the trap. Whether a large-scale effective lithologic trap can be formed in this area is a key issue facing exploration.

[0158] Based on the fission track analysis of the drilled bedrock tuff and the restoration of structural evolution, the uplift-subsidence evolution process of the uplift provenance area was reconstructed, and it was clarified that the provenance area of ​​the Songnan Low Uplift had a pattern of high in the west and low in the east during the Eocene-Early Oligocene, and a pattern of high in the east and low in the west after the Late Oligocene. The provenance area of ​​the Yongle 10 area in the eastern section of the Songnan Low Uplift was inheritedly developed in the Early Oligocene and Late Oligocene, with the characteristics of dynamic source supply and the material basis for the formation of large lithological traps. The Yongle 10a structure developed a transition zone controlled by the F10-1 and F1 faults, which was controlled by multiple levels of forward faults, forming two stages of deltas in the low-level and high-level domains of the Ling III segment, and the quantitative restoration of the erosion volume of the Ling III segment in the high-level period was about 23km. 3, the average thickness of the sandstone is predicted to be 54m. Two lobes, the west branch and the east branch, were identified. The west branch lobe is larger in scale and the fault controls its migration to the NE direction. The north side of Yongle 10a is sealed by the F1 fault. The F1 fault had an activity rate of <30m / Ma at the end of the Lingshui Formation deposition and stopped activity early. The F1 fault has a large fault throw and is sealed with thick marine transgressive mudstone. The fault-cap ratio is about 0.5-0.7, and the closure plugging capacity and fault preservation conditions are good. At the same time, the F1 fault is curved, and S-shaped pressurization occurs under the action of oblique extension to further strengthen the plugging. Based on the above research, it is confirmed that the third section of the Yongle 10a Lingshui Formation is a trap controlled by a forward fault.

[0159] The Yongle 10a structure receives hydrocarbons from the Baodao Sag, and natural gas is transported and accumulated in a step-by-step manner through the source faults, structural ridges and sand bodies. The source rocks in the Baodao Sag began to generate a large amount of hydrocarbons since 25.5Ma. The control faults continued to be active until the end of the Miocene (5.5Ma) and had a long activity period. The activity rate of the control faults exceeded 60m / Ma, which was conducive to the continuous filling of natural gas. The control faults stopped being active in the late Oligocene-Early Miocene, and the activity rate of the control faults was less than 30m / Ma. The trap began to form at 23Ma and was basically finalized at about 18.3Ma. The trap was formed early and could capture multiple periods of oil and gas. The preservation conditions in the later period were good. It is comprehensively predicted that the main accumulation period of the Yongle 10 structure was 23-5.5Ma, and the natural gas was continuously filled. Figure 3 shown.

[0160] The relationship between the fault activity and gas column height in the drilled structural area of ​​Baodao Sag and its surrounding area is statistically analyzed. Figure 4 As shown in the figure, the threshold ranges of gas column height evaluation in this area are 0-100m, 100-200m, and greater than 200m, and the corresponding threshold ranges of fault activity rate as evaluation prediction parameter are greater than 50-80m / Ma, 30-50m / Ma, and 0-30m / Ma. Therefore, the predictions for the structural areas not revealed by drilling are as follows:

[0161] When the fault activity rate is greater than 80 m / Ma, the predicted gas column height is 0, making it difficult to form gas reservoirs;

[0162] When the fault activity rate is between 50 and 80 m / Ma (excluding 50 m / Ma and including 80 m / Ma), the predicted gas column height is between 0 and 100 m (including 100 m), and the accumulation scale is relatively small;

[0163] When the fault activity rate is between 30 and 50 m / Ma (excluding 30 m / Ma and including 50 m / Ma), the predicted gas column height is between 100 and 200 m (excluding 100 m and including 200 m), and the accumulation scale is relatively large;

[0164] When the fault activity rate is between 0 and 30 m / Ma (including 30 m / Ma), the predicted gas column height is greater than 200 m and the accumulation scale is large.

[0165] According to the relationship between the corresponding fault activity rate and the gas column height, the undrilled Yongle 10a well revealed that the late fault activity rate of the control circle was less than 30m / Ma, and the corresponding predicted gas column height could exceed 200m. The actual drilling of the Yongle 10a well revealed that the gas column height reached 300m, confirming that the Yongle 10a structure is a natural gas-rich area.

[0166] In the specific contents of the above-mentioned specific implementation methods, the various technical features can be combined in any non-contradictory manner. In order to make the description concise, not all possible combinations of the above-mentioned technical features are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0167] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for evaluating the effectiveness of a fault-controlled lithologic trap, characterized in that: The steps include: S1. Quantitative structural uplift and provenance erosion; where: S11. Based on the understanding of regional tectonic evolution, combined with the LA-ICPMS apatite fission track experimental method, the relevant parameters of the parent rock area revealed by drilling in the provenance area are experimentally measured, and the tectonic uplift height and tectonic uplift rate are calculated; among which: The structural uplift height The calculation formula is: ； The uplift rate The calculation formula is: =(T i T0) / G / t ; Where, T i represents the closure temperature, T0 represents the surface temperature, G represents the paleo-geothermal gradient, and t represents the fission track age; S12. Take typical structural survey lines in different directions of the provenance area and combine them with the balanced profile technology to restore the uplift-subsidence dynamic evolution process of the provenance area and calculate the erosion thickness of the provenance area; wherein the erosion thickness The calculation formula is: ； In the formula, Indicates the depth of the drilling formation. represents the depth of the unconformity; S13. Determine the denudation area by using 3D seismic data above the sedimentary stratum boundary in the study area, and then calculate the amount of denudation; wherein the amount of denudation is The calculation formula is: ； In the formula, Indicates the denudation area; S2. Determine the distribution direction and range of lithologic trap sediments by combining rock and mineral geochemistry and fault patterns, and obtain the lithologic trap sediment volume; S3. comparing the amount of denudation with the sedimentary volume of the lithologic trap; when the amount of denudation is greater than or equal to the sedimentary volume of the lithologic trap, it indicates that there is a material basis for the formation of a large lithologic trap; otherwise, it indicates that the material basis for the development of a large lithologic trap is low; S4. For those with the material basis for the formation of large lithologic traps, the boundaries of small-layer lithologic traps shall be determined, and the types of lithologic traps shall be determined as traps controlled by either sequential or non-sequential faults; S5. Evaluate the effectiveness of traps controlled by forward faults.

2. The method for evaluating the effectiveness of a fault-controlled lithologic trap according to claim 1, characterized in that: In step S11, the calculation formula of the fission track age t is: ； In the formula, express 238 The total decay constant of U, represents the correction factor, represents the spontaneous track density, The LA-ICPMS apatite fission track experiment shows 238 U concentration; The calculation formula of the paleo-geothermal gradient G is: G=(T i T0) / 100 ; Where, T i represents the closed temperature, T0 represents the surface temperature, Indicates the depth of the drilling formation.

3. The method for evaluating the effectiveness of a forward fault-controlled lithologic trap according to claim 1, characterized in that: The step S2 comprises: S21. Interpret 3D seismic data in the study area, conduct regional interpretation of fault systems and sedimentary strata, and identify regional fault systems; S22. Compare the fault scale, spatial morphology and stratigraphic thickness of the upthrust and downthrust walls of the identified regional fault system to clarify whether the main sedimentary faults in the fault system have a significant controlling effect on the distribution of sedimentary strata; S23. For those with obvious control effects, identify the main source injection area that controls source injection and the conversion slope or fault zone that controls the transportation of debris materials; S24. Under the determination of the injection area of ​​the main source and the conversion slope or fault zone, based on the drilling revealed sedimentary strata or parent rock strata and zircon age spectrum, heavy mineral combination of sedimentary strata, rock composition, and comparison of sedimentary strata and parent rock strata characteristics, clarify the main transportation and distribution direction of the clastic material entering each conversion slope or fault zone along the injection area of ​​the main source; S25. According to the transportation and distribution direction of the main body of the clastic material, the method of "following the terrain, removing faults, and strong attribute introduction" is adopted to confirm the sedimentary body, restore the distribution of the sedimentary body, and determine the sedimentary volume of the lithological trap.

4. The method for evaluating the effectiveness of a forward fault-controlled lithologic trap according to claim 3, characterized in that: In step S22, the comparison method includes: If the thickness of the strata on the downthrown side of the fault is greater than that on the upthrown side of the fault, > , it means that the corresponding fault is the main fault controlling the sedimentary strata, and the fault during the sedimentary period has a significant controlling effect on the distribution of sedimentary strata; If the thickness of the strata on the downthrown side of the fault is less than or equal to the thickness of the strata on the upthrown side of the fault, ≤ , it means that the corresponding fault was formed after the sedimentary strata were deposited, and the fault during the sedimentary period did not control the distribution of the sedimentary strata; In step S23, the method for identifying the main source injection area includes: comparing the paleo-drop and fault activity rate at different locations of the fault, and considering the area with relatively low paleo-drop and relatively low fault activity rate as the main source injection area; wherein: The calculation formula of the ancient drop △H is: △H ； The fault activity rate The calculation formula is: △H / △ ； In the formula, represents the thickness of the strata on the downthrown plate of the fault, Indicates the thickness of the fault uplift plate, △ Indicates the deposition time of the corresponding stratum.

5. The method for evaluating the effectiveness of a forward fault-controlled lithologic trap according to claim 3, characterized in that: In step S25, according to the transportation and distribution direction of the main body of clastic material, the terrain is followed from high to low, avoiding the controlling sedimentation faults, maintaining the continuity of the sedimentary body along the strong amplitude area, reconstructing the appearance of the original seismic phase axis, identifying the characteristics of the foreset downlap and the two-way downlap, restoring the morphology of the sedimentary body during the sedimentary period, determining the distribution range of the sedimentary body, and determining the sedimentary volume of the lithological trap; wherein, the sedimentary volume of the lithological trap The calculation formula is: ； In the formula, represents the sediment area, represents the depth of the sediment bottom, Indicates the depth of the top of the sediment body.

6. The method for evaluating the effectiveness of a forward fault-controlled lithologic trap according to claim 1, characterized in that: Step S4 includes: S41. Combine the sea level rise and fall curves of the target layer in the study area with the relative sea level changes determined by the rock and paleontological fossil combination revealed by key drilling, and establish a high-precision sequence stratigraphic framework for the target layer in the study area by combining well and seismic data, identify the initial flooding surface and the maximum flooding surface, divide the low-stand system domain, the transgressive system domain, and the high-stand system domain, make fine comparisons of small layers in each system domain, divide small-layer sand groups, and interpret the single-layer sand group stratigraphy and faults in the confirmed sedimentary bodies; S42. Based on the interpretation of single-layer sand group strata and corresponding sand group faults, the fault activity of each small-layer sand group controlling sedimentary faults is analyzed, and the activities of each lateral point of the controlling sedimentary faults are compared. The relatively weak activity area is taken as the main source injection port of the corresponding small-layer sand group, and the thickness distribution of the small-layer sand group is analyzed. The micro-paleomorphology is restored based on its thickness change. The geophysical attribute distribution of each small-layer sand group is determined by superimposing and extracting the characteristics of sand and mudstone in combination with the rock physical characteristics, and the lobe distribution characteristics of different sand groups are identified, and the corresponding lithological trap boundaries are determined; S43. For each sub-layer, the confirmed lithologic trap boundary is determined based on the change in seismic amplitude energy, lobe distribution characteristics, and changes in physical properties of the drilled wells to determine whether the lithologic trap is a trap controlled by a consequent fault or a trap controlled by a non-continuous fault.

7. The method for evaluating the effectiveness of a forward fault-controlled lithologic trap according to claim 1, characterized in that: The step S5 comprises: S51. Determine the main period of oil and gas accumulation; among which: S511. If there is an oil and gas layer revealed by drilling in the sedimentary strata in the study area, then execute step S512, otherwise execute step S513; S512. Determine the main period of oil and gas accumulation by combining forward modeling of hydrocarbon generation and expulsion of source rocks with analysis of fluid inclusions and burial history; S513. Determine the main period of oil and gas accumulation by combining forward modeling of hydrocarbon generation and expulsion of source rocks with activity analysis of faults controlling transport and faults controlling the circle; S52. Determine whether the trap-controlling fault is active after the main reservoir-forming period. If it is basically inactive, it is considered that the trap is effective. Otherwise, execute step S53; S53. If a fault nose trap is formed in the bending section of the controlling fault, the effectiveness of the trap is considered to be good; if the controlling fault forms a single fault block trap by pure tension, the effectiveness of the trap is considered to be poor.

8. The method for evaluating the effectiveness of a forward fault-controlled lithologic trap according to claim 7, characterized in that: The step S52 includes: judging whether the trap-controlling fault is active after the main reservoir-forming period; if it is basically inactive, it is considered that the trap is effective and can form reservoirs with a certain reservoir-forming scale; otherwise, step S54 is executed; The step S5 also includes step S54: for traps with good or poor effectiveness, predicting the scale of natural gas accumulation in different fault activity zones in the traps controlled by the forward faults.

9. The method for evaluating the effectiveness of a forward fault-controlled lithologic trap according to claim 8, characterized in that: The step S54 comprises the following steps: S541. For the structural area revealed by drilling, obtain the gas column height distribution, and obtain multiple gas column height evaluation threshold ranges according to different research areas; S542. Statistically analyze the fault activity rate, fault cover ratio, and effective thickness of fault contact in the structural areas with reservoir formation and those without reservoir formation in the structural areas revealed by drilling under similar hydrocarbon source conditions, and use them as prediction parameters to be evaluated; S543. Perform linear regression on the three prediction parameters to be evaluated in step S542 and the corresponding air column heights in step S541, and then select the prediction parameter to be evaluated with the best correlation with the air column height as the evaluation prediction parameter; for the evaluation prediction parameter, obtain the corresponding multiple evaluation prediction parameter threshold ranges according to the multiple air column height evaluation threshold ranges in step S541; S544. For the structural areas revealed by drilling, the reservoir scale is predicted by the gas column height evaluation threshold range to which the gas column height at the current position belongs; for the structural areas not revealed by drilling, the corresponding evaluation prediction parameters are obtained, and the reservoir scale is predicted by the evaluation prediction parameter threshold range to which the evaluation prediction parameters at the current position belong.

Images