Quantitative evaluation method for three-dimensional mudstone smearing effect of inclined composite fault

Abstract

The invention relates to a quantitative evaluation method for the mudstone smearing effect of a tendency compound fault, which can accurately calculate and determine the sealing capacity of the fault under different fault dip angle tendencies and stratigraphic dip angle tendencies, and realize the prediction and evaluation of the oil-gas migration direction. The method is used in oil gas fine exploration research of strike-slip fault zones in the quasi-middle region and the western depression region of the Eongorton basin, a large-scale thrust fault in the middle section of the south edge of the Eongorton basin and a normal fault in the Jiyang depression river region of the Bohai bay basin, a plurality of fault control oil gas enrichment favorable zones are successfully predicted, the drilling success rate is increased by 30%, and the method has the advantages of being simple in structure, convenient to operate and high in practicability. From the aspect of practice, it is fully proved that the technology is suitable for evaluation of fracture closure in the east and west of China, and plays an important role in prediction of fracture control oil and gas reservoirs and fracture migration pathways.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas exploration, and in particular to a quantitative evaluation method for three-dimensional mudstone smearing effect of a composite fault. Background Art

[0002] Faults are a very important structural type in oil and gas basins. Their formation and evolution not only control the structure and evolution of the basins, but also control the formation and development of traps, directly or indirectly control the development characteristics of source rocks and reservoirs in the basins, and control the migration, accumulation and distribution of oil and gas reservoirs. The control of faults on oil and gas accumulation is mainly manifested in the control of oil and gas migration, accumulation process and oil and gas distribution. Among them, the openness and closure of faults play an important role in the migration, accumulation and destruction and re-accumulation of oil and gas reservoirs. Dip composite faults emphasize the combined relationship between faults and formation dips, which can be divided into: forward faults and reverse faults. A forward fault refers to a fault whose dip is the same or similar to the dip of the formation; a reverse fault refers to a fault whose dip is opposite to the dip of the formation. Dip composite faults are widely distributed in oil and gas basins in the east and west of my country, and have a significant control on oil and gas accumulation, but the evaluation method of their closure needs to be strengthened.

[0003] Fault closure has always been an important research issue of concern at home and abroad. In the early stages of fault closure research, field profile examples were mostly used to prove the existence of a set of sealing layers in the fault zone structure. Subsequently, five fault closure mechanisms were summarized based on the lithological differences, formation methods, and formation conditions of the sealing layers: 1) mudstone smear closure; 2) butt closure; 3) crushing closure; 4) diagenetic closure; 5) layer and sheet silicate closure. Today, the research on fault closure mainly tends to quantitatively study the various properties of the fault or the correlation between the ground stress and the formation of the sealing layer in the fault zone, and quantify the fault closure, which is conducive to analytical and comparative research.

[0004] Since it is found in actual petroleum exploration research that faults have duality, they can be used as channels for oil and gas migration, and can also control oil and gas reservoirs to block the transportation of oil and gas. How to judge the role of faults in the formation of oil and gas reservoirs is of vital importance for accurate drilling and oil finding, and reducing development costs. Fault sealing is often the most direct evidence for judgment. Therefore, a large number of research methods for fault sealing have emerged in recent years. For example, Allan proposed a fault two-plate sand-shale docking model in 1989. Through the known logging lithology information, the two-plate lithology docking combination under different fault distances was constructed, and the fault distance corresponding to the preferred docking combination was selected, so as to predict the strong sealing area in the three-dimensional fault spatial structure. Yielding proposed the parameter SGR (Shale Gouge Ratio) in 1997, which quantified the percentage of mud sealing layer in the fault zone, and made the fault sealing move from qualitative analysis to quantitative evaluation. Lv Yanfang, Fu Guang and others proposed the cross-section normal pressure method, which quantitatively evaluated the opening or closure of the fault by the pressure on the cross section. On the basis of the vertical normal stress of the section, Tian Hui further considered the influence of the mudstone content and sandstone content in the fault zone on the degree of internal fragmentation of the fault zone, and used the fault closure index method to evaluate whether the fault zone has formed cohesive fractures to meet the sealing conditions for oil and gas. There are also methods that use reservoir geochemistry methods to analyze the geochemical parameters of the oil layers near both sides of the fault to determine whether the fault has been connected from the accumulation period to the present, and whether the fault can block the lateral migration of oil and gas. There is also a method that uses the acoustic time difference to determine the size of the displacement pressure of the target rock formation, so as to analyze and determine the vertical sealing capacity of the fault. Of course, the above-mentioned fault closure evaluation methods currently have certain limitations, and there is a situation where the theoretical evaluation of favorable zones does not correspond to actual exploration.

[0005] With the deepening of geological exploration research, Sylvester proposed the strike-slip fault in 1988: a fault surface is nearly vertical, and the rock blocks on one side of the fault move horizontally relative to the rock blocks on the other side, which is significantly different from normal and reverse faults. The SGR (Shale Gouge Ratio) mudstone smear coefficient proposed by Yielding in 1997, its calculation formula is mainly applicable to the sliding model of faults on the vertical profile of normal and reverse faults, while strike-slip faults have tension-torsion and compression-torsion types, and the faults have both vertical sliding and horizontal dislocation. The two-dimensional calculation model of the SGR mudstone smear coefficient is obviously not applicable to the three-dimensional spatial dislocation of strike-slip faults. Therefore, Wu Kongyou et al. (2010) proposed the SSGR of the smear effect of tension-torsion faults for quantitative evaluation. This method requires observing the scratches on the section of the drilling core through the fault to obtain the sliding direction of the strike-slip fault in three-dimensional space. However, in actual operation, it is impossible to ensure that all faults have wells that penetrate the faults, and nearly vertical strike-slip faults cannot be drilled through by general drilling to extract the fault zone core. Therefore, it is impossible to accurately conduct a systematic evaluation of the fault closure of all faults in the study area. This method has the significant problem of insufficient applicability.

[0006] In reality, deep underground faults are often not pure normal or reverse faults that only slide vertically, but have a certain amount of horizontal displacement. Of course, they may also be strike-slip faults with the main displacement in the horizontal direction. Therefore, the previous evaluation of the closure of faults, due to the lack of reasonable methods, led to discrepancies between the evaluation results and the actual exploration situation.

[0007] The above information disclosed in the background technology is only used to increase the understanding of the background technology of the present application, and therefore, it may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention

[0008] The present invention provides a quantitative evaluation method for the three-dimensional mudstone smearing effect of inclined composite faults to solve the technical problem of insufficient applicability of the prior art. It can accurately calculate and determine the sealing capacity of faults under different fault dip angles and formation dip angles, and realize the prediction and evaluation of the oil and gas migration direction.

[0009] In order to achieve the above object, the present invention adopts the following technical scheme:

[0010] A quantitative evaluation method for three-dimensional mudstone smearing effect of a complex fault, the method comprising the following steps:

[0011] Step 1: Use the well logging curve and lithology data to correct the seismic profile, determine the layer position and fault position of the inclined composite fault, and determine whether the inclined composite fault belongs to a reverse fault or a forward fault; measure the fault strike and fault dip on the structural plane; select the marker layer as the equivalent layer on the profile, measure the vertical distance between the marker layer breakpoints, perform time-depth conversion, and obtain the vertical apparent fault distance H. 视 and the fracture dip angle δ;

[0012] Step 2: Project the lithology data onto the seismic profile, predict the lithology of the two plates of the fault according to the phase axis of the seismic profile, draw the lithology profile, obtain the lithology data of different layers of the two plates of the fault, and measure the vertical thickness h of each mudstone layer in the upper plate and the lower plate along the fault surface. i ;

[0013] Step 3: First, the time-depth relationship of the drilling records is used to construct a time-depth conversion model for the study area; secondly, a two-dimensional grid line interpretation is performed on the typical layers in the required study layers, and then the time-domain layers are converted into depth domains and their contour lines are assigned through the time-depth conversion model to obtain a stratigraphic layer depth contour map. The stratigraphic layer depth contour lines are used to easily obtain the stratigraphic dip, and then the ratio of the elevation difference between adjacent contour lines to the plane distance between adjacent contour lines is calculated, and the true stratigraphic dip angle α is obtained by combining the triangle inverse tangent function;

[0014] Step 4: based on the azimuth angle between the formation dip and the fault strike, obtain the acute angle β between the formation dip and the fault strike;

[0015] Step 5: Based on the type of the dip composite fault determined in step 1, the vertical thickness h i , vertical distance H 视 , fault dip angle δ, true formation dip angle α, and acute angle β between formation dip and fault strike are substituted into the following corresponding formula to calculate the three-dimensional mudstone smear coefficient TSGR:

[0016]

[0017] As described above, the quantitative evaluation method for the three-dimensional mudstone smearing effect of the inclined composite fault and the method for determining the type of the inclined composite fault are as follows: a fault inclination direction that is consistent with the formation inclination direction is a forward fault, and vice versa is a reverse fault.

[0018] The technical solution of the present invention has the following technical effects compared with the prior art: ① The method takes into account the influence of multiple fault-related geometric attributes under complex inclination, such as: fault dip, fault inclination, true formation dip, formation inclination, etc. on the fault mudstone smear evaluation value, so that the evaluation result is more accurate and the effect of predicting whether oil and gas are accumulated is more significant; ② The method takes into account the characteristics of the three-dimensional spatial movement of the fault and establishes four models: the forward tension-torsion model, the forward compression-torsion model, the reverse tension-torsion model, and the reverse compression-torsion model (see Figure 8 ), covering the contact between most faults and formations deep underground, and has strong universality; ③ This method is derived through geometric algebra, and there is no subjective formula creativity, which theoretically proves the feasibility of the evaluation method of three-dimensional mudstone smearing effect of inclined composite faults. ④ This method is used in the strike-slip fault zone in the central and western depression areas of the Junggar Basin, the large-scale thrust fault in the middle section of the southern margin of the Junggar Basin, and the fine oil and gas exploration research of normal faults in the Xianhe area of ​​the Jiyang Depression in the Bohai Bay Basin. It successfully predicted multiple fault-controlled oil and gas enrichment favorable zones, and increased the drilling success rate by 30%. From the practical level, it is fully proved that this technology is suitable for the evaluation of fault closure in eastern and western China, and plays an important role in the prediction of fault-controlled oil and gas reservoirs and fault migration pathways. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0020] Figure 1 This is the relationship diagram between the true fault distance and the apparent fault distance of the vertical fault.

[0021] Figure 2 It is a depth domain contour map of the stratigraphic layer.

[0022] Figure 3 This is a diagram showing the strike and dip angle of the stratigraphic fault.

[0023] Figure 4 This is a diagram showing the apparent inclination angle of the stratigraphic fracture surface.

[0024] Figure 5 This is the actual sliding distance mode diagram of the fault.

[0025] Figure 6 This is a diagram showing the length pattern of the active direction of the mudstone layer fault.

[0026] Figure 7 This is a planar stratigraphic structure map.

[0027] Figure 8This is a model diagram of forward compression-torsion, tension-torsion faults and reverse compression-torsion, tension-torsion faults.

[0028] Fig. 9 Schematic diagram of the principle of three-dimensional mudstone smearing on forward faults and reverse faults. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0030] In the description of the present application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0031] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0032] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0033] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0034] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplicity and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides various specific examples of processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0035] The present invention mainly uses the mudstone smearing sealing mechanism: since the mudstone layer has a strong plastic flow ability deep underground, during the fault activity, under the influence of the friction and traction of the section or fault zone, the mudstone layers on both sides of the fault will be smeared on the section or injected into the fault zone to form a mudstone sealing layer, thereby increasing the breakthrough pressure required for the oil and gas in the fault zone and blocking the lateral migration of oil and gas. The thickness of the mudstone layers on both sides of the fault is used to calculate the mud content involved in the fault zone. Drawing on the idea of ​​three-dimensional mudstone smearing proposed by Wu Kongyou et al. (2010), a general model of strike-slip faults is first established (i.e., fault inclination, fault dip, fault sliding direction, stratum dip, and fault dip are generalized), making the model more complex and closer to the actual situation underground. Secondly, through the geometric algebra method, the geometric properties of the fault and the formation that are not in the same plane in the three-dimensional space, such as the fault dip and inclination, the fault sliding direction, the formation dip and inclination, are converted to the two-dimensional plane of the fault surface (the mudstone length and the fault sliding distance in the fault sliding direction on the fault surface are obtained). Finally, the inclined composite mudstone smear parameters are calculated using the two-dimensional surface fault mudstone smear coefficient method proposed by Yielding in 1997. This method is an innovative improvement on the old method, which realizes the organic combination of complex three-dimensional space geometric properties and converts them into two parameters on the two-dimensional surface (i.e., the mudstone length in the fault sliding direction and the fault sliding distance). It not only considers multiple factors, making the method more accurate in the evaluation of closure, but also excludes the influence of the fault sliding direction (i.e., the core scratches across the fault) on the parameters of the two-dimensional plane in the process of converting the three-dimensional geometric properties to the two-dimensional plane, which makes the geometric properties required by this method easy to obtain accurately.

[0036] A quantitative evaluation method for the 3D mudstone smearing effect of inclined composite faults:

[0037] Step 1: The data used include high-precision 3D seismic data, 2D seismic profiles, well logging curves, lithology, planar stratigraphic structure maps, etc. In Petrel software, well logging curves and lithology data are used to correct seismic profiles, determine the stratigraphic positions and fault locations, and determine the type of dip composite faults, reverse faults or forward faults (see Figure 8 ), if the fault inclination direction is consistent with the formation inclination direction, it is a forward fault, otherwise it is a reverse fault; measure the fault strike on the structural plane (see Figure 7 ). Select the marker layer as the equivalent layer on the profile, measure the distance between the marker layer breakpoints, perform time-depth conversion, and obtain the vertical apparent break distance H. 视 and the fracture dip angle δ (see Fig. 9 ).

[0038] Step 2: After a detailed interpretation of the seismic profile, the logging lithology data was projected onto the seismic profile in CorelDRAW drawing software. The lithology of the two plates of the fault was predicted based on the event axis of the seismic profile, and the lithology profile was drawn to obtain the lithology data of different layers of the two plates of the fault. The vertical thickness h of each mudstone layer in the upper plate and lower plate was measured along the fault surface. i (See Fig. 9 ).

[0039] Step 3: In the Petrel software, firstly, the time-depth relationship of the drilling records is used to construct the time-depth conversion model of the study area. Secondly, the typical layers in the required study layers are interpreted in two dimensions. Then, the time-domain layers are converted into the depth domain and their contour lines are assigned through the time-depth conversion model to obtain the layer depth contour map (see Figure 2 ), a basic method for calculating the dip and inclination of formations using formation elevation lines: the downward direction of the vertical formation contour line is the formation dip, and the true dip angle α is obtained by combining the elevation difference of adjacent contour lines and the plane distance between them with the triangle inverse sine function relationship.

[0040] Step 4: Based on the relationship between the formation dip and the fault strike, the acute angle β between the formation dip azimuth and the fault strike azimuth can be obtained.

[0041] Step 5: Based on the type of composite fault determined in step 1, the vertical thickness of the hi formation, the vertical apparent fault distance H, the fault dip angle δ, the true formation dip angle α, and the acute angle β between the formation dip and the fault strike mentioned above are substituted into the corresponding formula below to calculate the three-dimensional mudstone smear coefficient:

[0042]

[0043] h i :i: thickness of rock layer unit (m); δ: fault dip angle; H 视 : vertical apparent distance of the fault (m); α: true dip of the formation (°); β: acute angle between the formation dip and the fault strike (°).

[0044] Fig. 9 Middle, H 真 : vertical true fault distance of the fault (m);

[0045] θ: side slope angle in the fault sliding direction (°);

[0046] γ': apparent dip angle on the stratigraphic section (°);

[0047] Blue filling layer: mudstone layer; yellow filling layer: sandstone layer.

[0048] The use of TSGR coefficient to evaluate the sealing property of inclined composite faults in clastic rock sequences is accurate and effective, and plays an important role in predicting the reserves of oil reservoirs. The required measurements can be obtained through seismic and logging data without experimental measurements, which ensures accuracy while also taking into account economy and convenience.

[0049] Feasibility description of the steps and the specific derivation process:

[0050] (1) Based on the literature review and summary of previous understanding of the regional geological background of the study area, the combined morphology of the fault structure in profile and plane was clarified according to seismic data, and the tension-torsion inclined composite fault was determined.

[0051] (2) Based on the detailed interpretation of the seismic profile, combined with the logging data, the location of the fault, the equivalent layers of the two fault plates, the location of the fault point, and the fault trend information are determined. The distance between the fault points is measured on the seismic profile, and the vertical apparent fault distance H is obtained through time-depth conversion. 视 and the fracture dip angle δ (see Figure 1 ), the plane display of the fault direction is determined by using geological interpretation software such as petrel.

[0052] Figure 1 Middle: H 视 : Apparent fault distance on the vertical section (the sum of the true fault distance and the distance misjudged due to formation inclination);

[0053] H 真 : the true fault distance on the vertical section;

[0054] δ: fracture inclination;

[0055] θ: side slope angle in the fault sliding direction;

[0056] γ': Apparent dip angle of the stratum on the section.

[0057] (3) Project the logging lithology data onto the seismic profile to obtain the lithology data of different layers on the two sides of the fault.

[0058] (4) Using geological interpretation software such as petrel, the stratigraphic identification of the required study layer is depicted as a two-dimensional grid. Based on the time-depth relationship of the well logging records in the study area, the two-dimensional time domain grid is transformed into the depth domain, and then the layer contour map is constructed (see Figure 2 ), the precise formation dip and true formation dip can be obtained from the formation contour lines in the figure.

[0059] (5) The formation dip, true dip and fault strike are obtained from steps 2 and 4. The apparent dip angles on the fault strike and dip can be obtained using the formation apparent dip formula (see Figure 3 ):

[0060] tanγ=tanαcosβ (1)

[0061] tanχ=tanαsinβ (2)

[0062] Combining (1) and (2) we get:

[0063] tanχ=tanγtanβ (3)

[0064]

[0065] Figure 3 Middle: h: vertical thickness of the formation;

[0066] α: true dip of the formation;

[0067] β: the acute angle between the formation dip and the fault strike direction;

[0068] γ: apparent dip angle in the direction of the formation fault;

[0069] χ: apparent dip angle in the direction of the formation fault;

[0070] δ: fracture dip angle;

[0071] θ: side slope angle in the fault sliding direction.

[0072] (6) Based on the fracture dip angles in steps 2 and 5 and the apparent dip angle in the fracture direction of the formation, the apparent dip angle γ' of the formation on the cross section can be obtained by simple geometric principles (see Figure 1 , Figure 4 ), determined to be a dip fault.

[0073] Figure 6 Middle: h: vertical thickness of the formation;

[0074] δ: fracture dip angle;

[0075] χ: the dip angle of the stratum along the fault dip direction;

[0076] θ: side slope angle in the fault sliding direction;

[0077] γ': apparent dip angle on the stratigraphic section;

[0078] γ: Apparent dip of the stratum along the strike direction of the fault.

[0079] First, the vertical thickness of the mudstone layer is converted into the thickness of the mudstone layer on the cross section by using the geometric algebra method. The specific implementation steps are as follows:

[0080] L IJ =L IL +L LJ (5)

[0081]

[0082] Let L LM is x, then L KM =L KL +x

[0083]

[0084] L KM =L KL +x (8)

[0085] L KM tanχ=xtanδ (9)

[0086] Combining (3), (7), (8), and (9), we get:

[0087]

[0088]

[0089] Combining (5), (6), (10), and (11), we get:

[0090]

[0091] In this way, the thickness of the stratum on the fracture surface can be obtained, and then the apparent dip angle of the stratum on the fracture surface can be calculated:

[0092] Based on the basic properties of a parallelogram: opposite sides are parallel and equal, we can get:

[0093]

[0094] Since the right triangle JIN (see Figure 4 ), according to the geometric law of right triangle:

[0095] L IJ =L IN tanγ' (14)

[0096] Combining (12), (13), and (14), we get:

[0097]

[0098] The apparent dip angle γ' of the formation section is obtained thereby.

[0099] (7) Due to the actual underground geological conditions, the strata often have a certain inclination angle, so the position of the fault equivalent point shown on the seismic section often has deviations caused by the inclination of the strata. What is observed is the vertical apparent fault distance (see Figure 1 , Figure 5), based on the apparent dip angle of the formation section obtained in the above steps, the real fault slip distance L can be obtained 滑 , the specific steps are as follows:

[0100] Figure 5 Middle: H 真 : true vertical fault distance;

[0101] H 视 : apparent vertical distance of the fault;

[0102] δ: fracture dip angle;

[0103] θ: side slope angle in the fault sliding direction;

[0104] γ': apparent dip angle on the stratigraphic section.

[0105]

[0106] H 视 =H 垂 +L PQ tanγsinδ (17)

[0107] H 垂 =L PQ tanθsinδ (18)

[0108] Combining (16), (17), and (18), we can obtain:

[0109]

[0110] (8) The horizontal length of the mudstone layer in the direction of the fault can be obtained by the apparent dip angle in the direction of the fault and the vertical thickness of the mudstone layer:

[0111]

[0112] (9) Based on the apparent dip angle of the cross section obtained in steps 6 and 8 and the horizontal length of the mudstone layer in the direction of the fault strike, the length of the mudstone layer along the fault active direction, L, can be obtained by simple geometric algebraic principles. TV (See Figure 6 ), the specific steps are as follows:

[0113] Figure 6 Middle: θ: side slope angle in the fault sliding direction;

[0114] γ': apparent inclination angle on the cross section.

[0115] Based on the properties of a parallelogram: opposite sides are parallel and equal, we can get:

[0116]

[0117] Let LTU is y, then L US =L TS -y

[0118]

[0119] L US tanγ'=ytanθ (22)

[0120] Combining (21) and (22), we can get:

[0121]

[0122] Thus L 泥1 You can solve it:

[0123]

[0124] (10) Based on the actual sliding distance of the fault obtained in step 7 and step 9 and the length along the sliding direction of the fault, the three-dimensional shale smear coefficient TSGR (Three-dimensional Shale Gouge Ratio) of the tensile-torsional fracture can be calculated. The specific calculation steps are as follows:

[0125]

[0126] Combining (2), (15), (19), (24), and (25), we can obtain:

[0127]

[0128] h i : vertical thickness of mudstone; δ: fault dip angle; H 视 : vertical apparent distance of the fault; α: true dip of the formation; β: the acute angle between the fault strike and the formation dip.

[0129] The above process finally derives the simplest expression of TSGR, which is not only applicable to the longitudinal tensile fault, but also applicable to the longitudinal compressive fault through geometric algebra method. Based on the required physical quantities in this expression, the accurate three-dimensional longitudinal fault mudstone smear coefficient can be obtained.

[0130] Using the above method, the reverse fracture model is established ( Fig. 9 ), and then perform geometric algebraic derivation to obtain the reverse fault three-dimensional mudstone smear coefficient (TSGR):

[0131]

[0132] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A quantitative evaluation method for the three-dimensional mudstone smearing effect of a complex fault, characterized in that: The method comprises the following steps: Step 1: Use the well logging curve and lithology data to correct the seismic profile, determine the layer position and fault position of the inclined composite fault, and determine whether the inclined composite fault belongs to a reverse fault or a forward fault; measure the fault strike and fault dip on the structural plane; select the marker layer as the equivalent layer on the profile, measure the vertical distance between the marker layer breakpoints, perform time-depth conversion, and obtain the vertical apparent fault distance H. 视 and the fracture dip angle δ; Step 2: Project the lithology data onto the seismic profile, predict the lithology of the two plates of the fault according to the phase axis of the seismic profile, draw the lithology profile, obtain the lithology data of different layers of the two plates of the fault, and measure the vertical thickness h of each mudstone layer in the upper plate and the lower plate along the fault surface. i ; Step 3: First, the time-depth relationship of the drilling records is used to construct a time-depth conversion model for the study area; secondly, a two-dimensional grid line interpretation is performed on the typical layers in the required study layers, and then the time-domain layers are converted into depth domains and their contour lines are assigned through the time-depth conversion model to obtain a stratigraphic layer depth contour map. The stratigraphic layer depth contour lines are used to easily obtain the stratigraphic dip, and then the ratio of the elevation difference between adjacent contour lines to the plane distance between adjacent contour lines is calculated, and the true stratigraphic dip angle α is obtained by combining the triangle inverse tangent function; Step 4: based on the azimuth angle between the formation dip and the fault strike, obtain the acute angle β between the formation dip and the fault strike; Step 5: Based on the type of the dip composite fault determined in step 1, the vertical thickness h i , vertical distance H 视 , fault dip angle δ, true formation dip angle α, and acute angle β between formation dip and fault strike are substituted into the following corresponding formula to calculate the three-dimensional mudstone smear coefficient TSGR:

2. The quantitative evaluation method for three-dimensional mudstone smearing effect of inclined composite fault according to claim 1 is characterized in that: The method to determine the type of dip composite fault is: if the fault inclination direction is consistent with the formation inclination direction, it is a forward fault; otherwise, it is a reverse fault.

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