CN117348063B - Evaluation method for quantitatively representing width of reverse fault fracture zone - Google Patents
Evaluation method for quantitatively representing width of reverse fault fracture zone Download PDFInfo
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Abstract
The application relates to the technical field of oil and gas exploration, in particular to an evaluation method for quantitatively representing the width of a fracture zone of reverse fault fracture, which comprises the following steps: preferably, the amplitude-preserving fidelity seismic data are selected, and a seismic research work area is established; calibrating a target earthquake geological horizon interface by adopting a calibration technology; tracking and comparing the three-dimensional data seismic stratum by using the seismic stratum interface calibration result; according to geological laws, the sensitive attribute of the fracture zone is preferably selected through statistical analysis; the application utilizes the seismic data, realizes qualitative description promotion and upgrading from conventional fault fracture zone width to quantitative characterization by optimizing the sensitive attribute of the fracture zone, and provides the most direct scientific basis for oil and gas exploration and development, especially for the drilling deployment of the unconventional oil and gas exploration and development in recent years, thereby greatly reducing the drilling risk, improving the exploration and development benefit, and simultaneously providing important support for large engineering site selection, geological disaster prevention and control and prediction decision.
Description
Technical Field
The invention relates to the technical field of oil and gas exploration, in particular to an evaluation method for quantitatively representing the width of a fracture zone of reverse fault fracture.
Background
The research of fault fracture zones is not only the field of long-term attention of basic disciplines such as structural geology, natural seismology and the like, but also the key point and the difficulty of attention in the conventional and unconventional oil and gas reservoir exploration and development field, and is also important for preventing and controlling and predicting geological disasters. In the oil and gas field, the description and accurate definition of fault fracture zone boundaries have great practical significance for drilling deployment: aiming at the conventional oil and gas reservoirs, the underground fault fracture zone can be generally used as an effective oil and gas migration channel and can directly provide an oil and gas reservoir space, so that the fracture zone range is defined as accurately as possible in the oil and gas exploration and development process, and a well track target body is designed to fall in a reservoir optimal development area of the fracture zone as far as possible; for unconventional oil and gas reservoirs such as shale gas, dense gas and coalbed gas, the fracture zone often damages the reservoir space and the original attached state of oil and gas, a channel is provided for secondary migration of the oil and gas, and the oil and gas escapes due to development of the fracture zone, so that the fracture zone is damaged, and the well drilling is required to avoid the deployment of the fracture zone. Therefore, fracture bandwidth is one of the most central indexes affecting well drilling deployment, whether it is the exploration phase or the development phase, and accurate characterization of fracture zone width is a long-sought goal of oil and gas practitioners.
Currently, in the field of oil and gas exploration and development, fault fracture zone research is mainly realized through three ways, namely field outcrop observation, well drilling well hole disclosure and geophysical interpretation. The outdoor outcrop observation is controlled by factors such as limited surface outcrop, surface vegetation, fourth-line sediment coverage and the like, so that the characteristics of a fault fracture zone are difficult to accurately describe, and the fracture development condition of a few kilometers of the deep buried underground cannot be clearly and clearly observed through similar outcrop observation. While the well bore can reveal the crack development condition with centimeter-level precision around the well bore, the well bore is limited by factors such as the oil and gas exploration and development stage, the well pattern density, the limited coring section, the strong geological heterogeneity and the like, and the fault fracture zone with three-dimensional characteristics is difficult to accurately describe by a hole or a plurality of holes. Geophysical description is capable of detecting deep buried strata, and particularly with the development of high-precision three-dimensional seismic detection technology, the acquisition and detection precision is remarkably improved, and the method gradually becomes the most effective method for carving underground faults and breaking zones thereof.
Currently, a division method and a device for the internal structure of a carbonate sliding fracture breaking belt are provided in a patent document with a patent number of CN202010277876.6, wherein the division method comprises the steps of obtaining the characteristics of the carbonate sliding fracture breaking belt; features including cracks, holes, and caves; dividing a carbonate sliding fracture breaking zone into a first type, a second type and a third type according to the characteristics; in the method technology of the patent, how to identify the fracture zone spatially is not related, and there is no mention of evaluating the fracture development width by adopting an earthquake means, and improvement is needed.
Disclosure of Invention
The invention aims to provide an evaluation method for quantitatively representing the width of a fracture zone of an inverse fault, and aims to realize qualitative description propulsion and upgrading from conventional fracture zone width to quantitative representation by optimizing sensitive attribute attributes of the fracture zone by utilizing seismic data, thereby providing the most direct scientific basis for oil and gas exploration and development, especially for the drilling deployment of the unconventional oil and gas exploration and development in recent years, greatly reducing drilling risks, improving exploration and development benefits, and simultaneously providing important support for large-scale engineering site selection, geological disaster prevention and control and prediction decision.
In order to achieve the above object, the present invention provides an evaluation method for quantitatively characterizing a reverse fault fracture zone width, comprising:
preferably, the amplitude-preserving fidelity seismic data are selected, and a seismic research work area is established;
Calibrating a target earthquake geological horizon interface by adopting a calibration technology;
Tracking and comparing the three-dimensional data seismic stratum by using the seismic stratum interface calibration result;
according to geological laws, the sensitive attribute of the fracture zone is preferably selected through statistical analysis;
utilizing the explained seismic interface and the sensitivity attribute to compile a sensitivity attribute plan;
dividing a fault into a plurality of sampling interpretation points in a sensitive attribute plane distribution diagram along the trend of the fault;
According to the fault control points, compiling a graph of distance from the break point and fracture development probability;
Acquiring a reverse fault fracture zone development curve by using a break point distance-fracture development probability curve graph;
acquiring attribute values of a fault-free development influence area;
And obtaining the width value of the fracture zone of fracture by using a fracture development probability second derivative curve.
Wherein, the preferred fidelity seismic data of the amplitude preservation, the concrete step of establishing the seismic research work area includes:
Loading conventional three-dimensional seismic data, rapidly cutting a browsing section, roughly observing the existence range of the fault seismic response characteristics of the seismic section, and preliminarily determining the space extension range of the fault to be analyzed, wherein the seismic response characteristics mainly comprise in-phase inversion, in-phase axis wave group dislocation or in-phase axis deflection and the like;
And selecting a seismic data body containing faults according to the longitudinal and transverse extension scale of the reverse faults to be researched, wherein the data body is required to be offset and superimposed with pure wave data.
The specific steps of calibrating the target earthquake geological horizon interface by adopting the calibration technology comprise:
Selecting a proper well drilling to perform well earthquake calibration, and calibrating and researching the earthquake position of a target layer;
When the drilling disclosure exists in the area of the target layer, the drilling is directly utilized to mark the longitudinal position of the well point seismic target layer;
When no well drilling occurs in the area where the target layer is located, the patent ZL202210140082.4 or a wave group characteristic analysis method is adopted to mark the layer level interface of the target layer.
When the drilling is revealed in the area of the target layer, the specific step of directly calibrating the longitudinal position of the seismic target layer at the well point by using the drilling comprises the following steps:
Selecting drilled wells in the space ranges on the two sides of the upper disc and the lower disc of the target fault to lay a foundation for later well shock comparison and crack analysis, wherein the selected wells are required to meet acoustic time difference curves, density curves and shaft imaging logging data containing complete target layers;
Generating a synthetic record by utilizing the simulation of the acoustic wave time difference and the density curve, fixing the seismic section, under the constraint of a macroscopic geological structure and drilling layering, selecting a time window range of 1-2 periods by moving the synthetic record up and down, calculating the correlation value between the seismic reflection wave and the synthetic record, and taking the position with the maximum correlation value as the position with the highest wave group similarity, wherein the point is the well vibration matching, so that the longitudinal matching of the drilling layering and the seismic layering is realized;
and calibrating the longitudinal position of the well point seismic target layer by the single well geological stratification position.
The specific steps of tracking and comparing the three-dimensional data seismic stratum by utilizing the seismic stratum interface calibration result comprise:
Calibrating well point seismic stratum results aiming at a well earthquake combined target layer, and summarizing the reflection characteristics of the target layer seismic reflection phase-axis wave group, wherein the reflection characteristics of the target layer seismic reflection phase-axis wave group comprise polarity, amplitude and continuity;
and (5) tracking, comparing and explaining by utilizing the reflection characteristics of the seismic wave groups of the seismic stratum.
The specific steps for compiling the sensitive attribute plan by utilizing the explained seismic interface and the sensitive attribute include:
Extracting sensitive attribute values in a given time window by using a seismic interface, and averaging the attribute values in a limited time window to serve as sensitive attribute values A ij at coordinate points, wherein i and j are respectively the longitudinal grid counting points of the seismic grid;
Using the attribute value discrete point A ij, the earth coordinates at that point and the attribute value A ij are combined and meshed to form a sensitive attribute plane distribution map.
The specific steps for compiling the distance from the fault point to the fault development probability curve graph according to the fault control point comprise the following steps:
On the sensitive attribute plane distribution diagram, P i is taken as a central point to be a line segment perpendicular to a fault plane, lmax/2 length is respectively taken at two sides of a fault control point, the center of a fault breakpoint is taken as an original point, the lower disc end of the fault is negative, the upper disc end is positive, m points are taken at intervals of one surface element from the upper disc, wherein m is Lmax/2, the whole sum of 1 is recorded as D ij (i epsilon 1, n, j epsilon 1, m);
Respectively reading the sensitive attribute values of the upper disc layer and the lower disc layer, wherein each repeated point takes the maximum value of the sensitive attribute values as a discrete point D ij of the sensitive attribute value of the broken belt;
And respectively utilizing the discrete point data of the line segments perpendicular to the fault plane at N P i, taking the distance from the fault origin as a horizontal axis and the discrete point D ij of the sensitive attribute value of the fracture breaking zone as a vertical axis to compile a graph C i (i E [1, N ]) of the distance from the fault point and the fracture development probability.
The specific steps of acquiring the reverse fault fracture zone development curve by utilizing the separation point distance-fracture development probability curve graph include:
Overlapping N separation point distance-fracture development probability curves C i according to coordinates;
Analyzing the fluctuation trend of the N curves C i, and if a curve inconsistent with the overall trend exists, discarding the curve as an abnormal curve;
solving an average line C AVG of the residual break point distance-breaking development probability curve C i;
And carrying out median filtering on the C AVG to eliminate abnormal spike interference, wherein the filtered curve is the fracture zone development curve C of the reverse fault.
The specific step of acquiring the attribute value of the fault-free development influence area comprises the following steps:
aiming at a well drilling area, the sensitive attribute of the fracture-free development position of the target layer can be used as a fracture-free base value D0, and aiming at the well drilling area, the second derivative C' of the fracture zone development curve of the reverse fault is utilized to represent the change inflection point of the fracture development concentration degree;
a second derivative C' graph is compiled, and the two sides of the curve are in a collaborative state;
And calibrating a C curve point intersection point D 0 at the point of the C sharp point inflection point, wherein the point represents the boundary of a fault development zone, and the fracture breaking zone is close to the center.
The specific steps of obtaining the width value of the fracture zone of the fault fracture through the second derivative curve of the fracture development probability comprise the following steps: the distance from the upper disc D 0 and the lower disc D 0 of the reverse fault to the original point 0 is respectively read to obtain the width value of the broken belt of the upper disc and the lower disc of the fault, and the sum of the widths of the broken belts of the upper disc and the lower disc is the total width value of the broken belt of the fault.
According to the evaluation method for quantitatively representing the width of the fracture zone of the reverse fault, aiming at the repeated occurrence of the upper and lower disc seismic geologic horizons of the reverse fault, the maximum value is selected, so that the seismic sensitivity attribute value of the core region of the fracture zone is increased, the fault core characteristics are prevented from being omitted due to repeated stratum omission, and the fault core of the fracture zone is further defined; aiming at two possible situations of drilling and drilling without well, obtaining the base value of the sensitive attribute without crack is provided, the quantitative determination of the fracture crack range is realized, the defect of subjectivity of the sensitive attribute of the fracture zone for manual setting is avoided, the distance from the maximum value of the sensitive attribute of the fracture zone to the base value is calculated to be the development width of the fracture zone, and more rigorous basis is provided for well position deployment in oil and gas exploration and development.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of an evaluation method for quantitatively characterizing reverse fault fracture zone width of the present invention.
FIG. 2 is a schematic view of a rapid-cutting view cross-section of an exemplary embodiment of the present invention.
FIG. 3 is a graph comparing post-stack seismic profiles (a) with stacked fracture sensitivity profiles (b) provided by an embodiment of the invention.
Fig. 4 is a schematic diagram of obtaining a position of sensitive attribute of a fracture zone by superposition of sensitive attribute plane distribution according to an embodiment of the present invention.
FIG. 5 is an analysis chart of the development width curve of the reverse fracture zone according to an embodiment of the present invention.
FIG. 6 is a flow chart of the preferred amplitude-preserving fidelity seismic data of the present invention, creating a seismic survey work area.
FIG. 7 is a flow chart of the present invention for calibrating a target seismic geologic horizon interface using a calibration technique.
FIG. 8 is a flow chart of the present invention for calibrating the longitudinal position of a well point seismic target zone when the target zone has a well zone.
FIG. 9 is a flow chart of the present invention for tracking and comparing three-dimensional data seismic formations using seismic formation interface calibration results.
FIG. 10 is a flow chart of the present invention for compiling a sensitive attribute plan using an interpreted seismic interface and sensitive attributes.
FIG. 11 is a flow chart of a graph of distance from a breakpoint versus probability of fracture development, according to fault control points of the present invention.
FIG. 12 is a flow chart of the invention for obtaining a reverse fault fracture zone development curve using a break point distance-fracture development probability graph.
Fig. 13 is a flowchart of acquiring attribute values of an influence region of the tomosynthesis of the present invention.
Detailed Description
Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative and intended to explain the present invention and should not be construed as limiting the invention.
Referring to fig. 1 to 13, the invention provides an evaluation method for quantitatively characterizing a fracture zone width of an inverse fault, which comprises the following steps:
S1, preference is given to amplitude-preserving fidelity seismic data, and a seismic research work area is established;
The method comprises the following specific steps:
S11, loading conventional three-dimensional seismic data, rapidly cutting a browsing section, roughly observing the existence range of the fault seismic response characteristics of the seismic section, and preliminarily determining the space extension range of the fault to be analyzed, wherein the seismic response characteristics mainly comprise in-phase inversion, in-phase axis wave group misplacement or in-phase axis deflection;
S12, selecting a seismic data body containing faults according to the longitudinal and transverse extension scale of the reverse faults to be researched, wherein the data body is required to be offset and superimposed with pure wave data.
S2, calibrating a target earthquake geological horizon interface by adopting a calibration technology;
The method comprises the following specific steps:
S21, selecting a proper drilling or outcrop section to carry out fine well earthquake calibration, and calibrating the accurate position of a research target layer on an earthquake section;
s22, when the drilling disclosure exists in the area of the target layer, the drilling is directly utilized to calibrate the longitudinal position of the seismic target layer at the well point;
The method comprises the following specific steps:
S221, selecting drilled wells in the space ranges of the two sides of the upper and lower plates of the target fault to lay a foundation for later-stage well shock comparison and crack analysis, wherein the selected wells are required to meet acoustic time difference curves, density curves and shaft imaging logging data containing complete target layers;
S222, generating a synthetic record by utilizing the simulation of the acoustic time difference and the density curve, fixing the seismic section, under the constraint of a macroscopic geological structure and drilling layering, selecting a time window range of 1-2 periods by moving the synthetic record up and down, calculating the correlation value between the seismic reflection wave and the synthetic record, and taking the position with the maximum correlation value as the highest wave group similarity, wherein the point is the well earthquake matching, so that the longitudinal matching of the drilling layering and the seismic layering is realized;
s223, calibrating the longitudinal position of the well point seismic target layer through the single well geological stratification position.
S23, when no well drilling occurs in the area where the target layer is located, calibrating a layer level interface of the target layer by adopting a patent ZL202210140082.4 or adopting a wave group characteristic analysis method;
The non-well zone is used for calibrating the layer level interface of the target layer through the invention patent ZL202210140082.4 or by adopting a wave group characteristic analysis method.
S3, tracking and comparing the three-dimensional data seismic stratum by utilizing the seismic stratum interface calibration result;
The method comprises the following specific steps:
s31, calibrating well point seismic stratum results aiming at a well earthquake combined target layer, and summarizing reflection characteristics of a target layer seismic reflection phase-axis wave group, wherein the reflection characteristics of the target layer seismic reflection phase-axis wave group comprise polarity, amplitude and continuity;
S32, tracking, comparing and explaining by utilizing the reflection characteristics of the seismic wave groups of the seismic stratum;
And (5) tracking, comparing and explaining by utilizing the reflection characteristics of the seismic wave groups of the seismic stratum. When tracking, the tracking range is ensured to be larger than the maximum distance from the fault to the adjacent fault at the periphery, and the maximum distance is recorded as Lmax; if the three-dimensional area has no fault adjacent to the three-dimensional area, returning to the first adjustment step, adjusting the S3 to be the primary coverage of the whole earthquake area, and tracking the earthquake stratum, wherein the whole three-dimensional area data body needs to be tracked, and Lmax is the maximum value to the boundary.
S4, according to geological laws, the sensitivity attribute of the fracture zone is preferably selected through statistical analysis;
S41-S44 are performed for the investigation region where known wells are present, S43-S44 are performed for the no well region, and fracture development characteristics are summarized, and fracture zone sensitivity properties are preferred.
S41, counting the number of cracks of a target layer by using single-well imaging logging data of upper and lower discs on two sides of a fault, wherein the counted wells ensure that developed cracks and undeveloped cracks are distributed as much as possible;
s42, analyzing the relation between the number of the well cracks and the distance, finding out wells close to the fault non-development cracks, and preliminarily determining the macroscopic range of the fault affected fracture zone;
S43, respectively extracting attributes which are possibly related to fracture zones by utilizing the stratum layers of the objective layer, wherein the attributes comprise seismic coherence, similar attributes and fault probability attributes, so as to form a fracture zone sensitive attribute group;
S44, aiming at the well region, respectively picking up single attribute values in the attribute group at the well point, comparing the known change trend of the crack at the well point with the change trend of the attribute, and preferentially selecting the attribute with the same trend, wherein the attribute with good change dispersion degree of the trend is used as the sensitive attribute A of the fracture breaking zone. Aiming at the non-well region, judging whether the fracture is developed or not according to the mess degree of the seismic reflection at the fault edge, further judging whether the attribute is sensitive or not, if the trend characteristic is obvious, indicating that the seismic attribute has sensitivity to the development of the fracture, comparing and sequencing the sensitivity degree of the attribute, and determining the most sensitive attribute as the sensitivity attribute A of the fracture zone.
S5, utilizing the explained seismic interface and the sensitivity attribute to compile a sensitivity attribute plan;
The method comprises the following specific steps:
S51, extracting sensitive attribute values in a given time window by utilizing a seismic interface, and averaging the attribute values in a limited time window to serve as sensitive attribute values A ij at coordinate points, wherein i and j are respectively counting points of a longitudinal grid and a transverse grid of the seismic grid;
S52, utilizing the attribute value discrete point A ij, combining the geodetic coordinates at the point with the attribute value A ij, and meshing to form a sensitive attribute plane distribution map.
S6, dividing the fault into a plurality of sampling interpretation points in a sensitive attribute plane distribution diagram along the fault trend;
on the sensitive attribute plane distribution diagram, observing the development degree of the associated faults along the fault trend, if the associated faults are more, the distance is properly reduced, more control points are added, and if the associated faults are less, the control points are properly reduced, so that the control points can clearly represent the whole fault. In other words, the control point n is generally selected depending on the development intensity of the fracture along the trend associated fault, and the value of n is small if the variation intensity is weak and the value of n is large if the variation intensity is large. These control points are denoted as P i (i.e. [1, n ]), divide the fault into n-1 line segments, the distance needs to be guaranteed to be not more than 1/2 of the length of the associated fault, but the minimum value must not be less than 3, and the distance between the line segments is at least more than 2 face elements.
S7, according to the fault control points, compiling a distance from the break point-fracture development probability curve graph;
The method comprises the following specific steps:
S71, taking Pi as a central point on a sensitive attribute plane distribution diagram as a line segment, taking Lmax/2 length at two sides of a fault control point, namely an upper disc end and a lower disc end, taking the center of a fault breakpoint as an original point, taking the lower disc end of the fault as negative, taking the upper disc end as positive, taking m points from an upper disc at a surface element interval, wherein m is Lmax/2, taking the whole sum of 1, and recording as D ij (i epsilon [1, n ], j epsilon [1, m ]);
S72, respectively reading the sensitive attribute values of the upper disc layer and the lower disc layer, wherein each repeated point takes the maximum value of the sensitive attribute values as a discrete point D ij of the sensitive attribute value of the broken belt;
S73, compiling a breakpoint distance-fracture development probability curve graph C i (i E [1, N ]) by using N pieces of discrete point data of line segments perpendicular to a fault plane at P i respectively, wherein the distance from a fault origin is taken as a horizontal axis, and the discrete point D ij of a fracture zone sensitive attribute value is taken as a vertical axis.
S8, acquiring a reverse fault fracture zone development curve by using a break point distance-fracture development probability curve graph;
The method comprises the following specific steps:
s81, superposing N separation point distance-fracture development probability curves C i according to coordinates;
S82, analyzing fluctuation trend of the N curves C i, and if a curve inconsistent with the overall trend exists, discarding the curve as an abnormal curve;
S83, solving an average line C AVG of a residual separation point distance-fracture development probability curve C i;
s84, carrying out median filtering on the C AVG to eliminate abnormal spike interference, wherein the filtered curve is the fracture zone development curve C of the reverse fault.
S9, acquiring attribute values of a fault-free development influence area;
The method comprises the following specific steps:
S91, aiming at a well drilling area, a sensitive attribute of a fracture-free development position of a target layer can be used as a fracture-free base value D 0, and aiming at the well drilling area, a second derivative C' is calculated by utilizing a fracture zone development curve of an inverse fault, and a fracture development concentration degree change inflection point is represented;
S92, compiling a second derivative C' graph, wherein the two sides of the curve are in a collaborative state;
S93, calibrating C curve point intersection points D 0 at the point of the C sharp point, wherein the points represent boundaries of fault development zones, and the fracture breaking zones are close to the center.
S10, obtaining a fault fracture breaking belt width value through a fracture development probability second derivative curve;
The method comprises the following steps: the distance from the upper disc D 0 and the lower disc D 0 of the reverse fault to the original point 0 is respectively read to obtain the broken belt width value of the upper disc and the lower disc of the fault, and the sum of the broken belt widths of the upper disc and the lower disc is the broken belt width value of the fault.
For a better understanding of the present invention, a specific example is described below, and the process flow is specifically as follows:
Taking a certain region of Sichuan basin Shunan as an example in the embodiment, after loading conventional three-dimensional seismic data, as shown in fig. 2, rapidly cutting a browsing section, wherein an F5 fault is taken as a research object, and the response characteristic of the fault is mainly a phase-axis wave group fault section and a deflection characteristic; and (3) researching the longitudinal and transverse extension scale of the F5 reverse fault according to the requirement, selecting a fault response range of 200 lines of transverse lines and 300 lines of longitudinal lines, and researching that the adopted data is prestack time offset superposition pure wave data.
According to the macroscopic feature of the Sichuan basin, the layer is reflected by two peaks and one trough, thick-layer clastic rock is arranged on the layer, the layer is reflected into medium continuous weak reflection, the medium continuous weak reflection is generalized to an embodiment block, the deposition environment is unchanged, and the layer is reflected by strong continuous peaks, as shown in fig. 2, so that the longitudinal position of the seismic target layer can be determined by using the method.
And the strong continuous wave peak reflection is taken as the reflection characteristic of the target layer earthquake in-phase axis wave group. Further, by utilizing the reflection of two peaks and one valley, the peak is selected, and the reflection characteristic tracking, comparison and interpretation of the earthquake wave group of the earthquake stratum are carried out. The tracking should ensure that the tracking range is greater than 3000m from the present fault to the adjacent fault at the periphery, and in this embodiment, for better representation, the seismic stratum is further tracked to the entire 200×300 channels area.
In the embodiment shown in fig. 3b, according to the fact that the seismic reflection disorder degree of the fault edge is moderate, the fracture characteristic trend characteristics are not obvious, the fault probability data trend is consistent with the section of fig. 3, the seismic attribute has sensitivity to crack development and can be used for representing the fracture zone development rule, and the attribute value is determined to be fracture zone sensitivity attribute A.
In the embodiment shown in fig. 3b, according to the fact that the seismic reflection disorder degree of the fault edge is moderate, the fracture characteristic trend characteristics are not obvious, the fault probability data trend is consistent with the section of fig. 3, the seismic attribute has sensitivity to crack development and can be used for representing the fracture zone development rule, and the attribute value is determined to be fracture zone sensitivity attribute A.
Extracting sensitive attribute values in a 20ms time window by using a seismic stratum, and averaging the attribute values in a limited time window to obtain sensitive attribute values A ij at a coordinate point, wherein i and j are respectively 200X 300 longitudinal and transverse grid counting points of a seismic grid; further, using the attribute value discrete points A ij (i ε [1,200], j ε [1,300 ]), a sensitive attribute plane distribution map as shown in FIG. 4 is formed by meshing.
According to the plane change condition of the sensitive attribute of the fracture zone shown in fig. 4 in the embodiment, 6 points are selected along the fault trend, the size of 22 surface elements of the seismic data is the interval, and the points P are uniformly selected.
In the embodiment, as shown in fig. 4, the scattered points in P are taken as central points and are perpendicular to the fault plane, two sides of the break point, namely, the upper disc end and the lower disc end are taken 1500m respectively, the center of the break point of the fault is taken as 0 point, the lower disc end of the fault is taken as negative, the upper disc end is taken as positive, and 59 points are taken from the upper disc at a unit interval; further, the sensitive attribute values of fracture zones of discrete points D ij (i epsilon [1,6], j epsilon [1,60 ]) are respectively read, and an overlapping area is formed between the upper disc and the lower disc of the F5 fault, so that the maximum value is obtained. Further, the discrete point data of line segments perpendicular to the fault plane at 6P i (i epsilon [1, 6) are respectively utilized, the distance from the fault origin is taken as a horizontal axis, the discrete point of the sensitive attribute value of the fracture zone is taken as a vertical axis, and a graph of the distance from the fault point and the fracture development probability is compiled (figure 5 a).
As shown in fig. 5a, 6 separation point distance-fracture development probability curves are superimposed according to coordinates; further, analyzing the fluctuation trend of the curves in fig. 5a, it can be seen that there is a curve with a curve which is obviously inconsistent with the trend of other curves, and the curve is discarded as an abnormal curve, so as to obtain fig. 5b; further, as shown in fig. 5c, the mean line of 5 distance-break development probability curves from the break point is obtained; further, as shown in fig. 5d, the mean value of the mean line is filtered to eliminate abnormal spike interference, and the filtered curve is the fracture zone development curve of the reverse fault.
Calculating a second derivative by using a fracture zone development curve of the reverse fault, and representing the fracture development concentration degree; further, as shown in FIG. 5e, a second derivative graph is compiled, which is generally in a collaborative state on both sides of the upper and lower plates; further, the C curve point intersection points 0.31 and 0.22 at the point of the C sharp point are marked, the points represent the boundary of a fault development zone, and the fracture breaking zone is close to the center.
In this embodiment, by reading the abscissa corresponding to the two spikes as-177 and 166, that is, the corresponding lower disc breaking belt influence width is 177m, the upper disc breaking belt influence width is 166m, and the total breaking influence width is 343m.
According to the evaluation method for quantitatively representing the width of the fracture zone of the reverse fault, aiming at the repeated occurrence of the upper and lower disc seismic geologic horizons of the reverse fault, the maximum value is selected, so that the seismic sensitivity attribute value of the core region of the fracture zone is increased, the fault core characteristics are prevented from being omitted due to repeated stratum omission, and the fault core of the fracture zone is further defined. Aiming at two possible situations of drilling and drilling without well, obtaining the base value of the sensitive attribute without crack is provided, the quantitative determination of the fracture crack range is realized, the defect of subjectivity of the sensitive attribute of the fracture zone for manual setting is avoided, the distance from the maximum value of the sensitive attribute of the fracture zone to the base value is calculated to be the development width of the fracture zone, and more rigorous basis is provided for well position deployment in oil and gas exploration and development.
The above disclosure is only a preferred embodiment of the present invention, and it should be understood that the scope of the invention is not limited thereto, and those skilled in the art will appreciate that all or part of the procedures described above can be performed according to the equivalent changes of the claims, and still fall within the scope of the present invention.
Claims (10)
1. An evaluation method for quantitatively characterizing the width of a fracture zone of an inverse fault is characterized by comprising the following steps:
preferably, the amplitude-preserving fidelity seismic data are selected, and a seismic research work area is established;
Calibrating a target earthquake geological horizon interface by adopting a calibration technology;
Tracking and comparing the three-dimensional data seismic stratum by using the seismic stratum interface calibration result;
according to geological laws, the sensitive attribute of the fracture zone is preferably selected through statistical analysis;
utilizing the explained seismic interface and the sensitivity attribute to compile a sensitivity attribute plan;
dividing a fault into a plurality of sampling interpretation points in a sensitive attribute plane distribution diagram along the trend of the fault;
According to the fault control points, compiling a graph of distance from the break point and fracture development probability;
Acquiring a reverse fault fracture zone development curve by using a break point distance-fracture development probability curve graph;
acquiring attribute values of a fault-free development influence area;
And obtaining the width value of the fracture zone of fracture by using a fracture development probability second derivative curve.
2. An evaluation method for quantitatively characterizing the width of a fracture zone of an inverse fault as claimed in claim 1, characterized in that,
The preferred fidelity seismic data comprises the following specific steps of:
Loading conventional three-dimensional seismic data, rapidly cutting a browsing section, roughly observing the existence range of the fault seismic response characteristic of the seismic section, and preliminarily determining the space extension range of the fault to be analyzed, wherein the seismic response characteristic mainly comprises in-phase inversion, in-phase axis wave group dislocation or in-phase axis deflection;
And selecting a seismic data body containing faults according to the longitudinal and transverse extension scale of the reverse faults to be researched, wherein the data body is required to be offset and superimposed with pure wave data.
3. An evaluation method for quantitatively characterizing the width of a fracture zone of an inverse fault as claimed in claim 2, characterized in that,
The specific steps of calibrating the target earthquake geological horizon interface by adopting the calibration technology comprise:
Selecting a proper drilling or outcrop section to carry out fine well earthquake calibration, and calibrating the accurate position of a research target layer on an earthquake section;
When the drilling disclosure exists in the area of the target layer, the drilling is directly utilized to mark the longitudinal position of the well point seismic target layer;
and when no well drilling occurs in the area where the target layer is located, calibrating the layer level interface of the target layer by adopting a wave group characteristic analysis method.
4. An evaluation method for quantitatively characterizing the width of a fracture zone of an inverse fault as claimed in claim 3,
The specific steps of directly calibrating the longitudinal position of the well point seismic target layer by using the drilling when the drilling is revealed in the area of the target layer comprise the following steps:
Selecting drilled wells in the space ranges on the two sides of the upper disc and the lower disc of the target fault to lay a foundation for later well shock comparison and crack analysis, wherein the selected wells are required to meet acoustic time difference curves, density curves and shaft imaging logging data containing complete target layers;
Generating a synthetic record by utilizing the simulation of the acoustic wave time difference and the density curve, fixing the seismic section, under the constraint of a macroscopic geological structure and drilling layering, selecting a time window range of 1-2 periods by moving the synthetic record up and down, calculating the correlation value between the seismic reflection wave and the synthetic record, and taking the position with the maximum correlation value as the position with the highest wave group similarity, wherein the point is the well vibration matching, so that the longitudinal matching of the drilling layering and the seismic layering is realized;
and calibrating the longitudinal position of the well point seismic target layer by the single well geological stratification position.
5. An evaluation method for quantitatively characterizing the width of a fracture zone of an inverse fault as claimed in claim 4, characterized in that,
The specific steps of tracking and comparing the three-dimensional data seismic stratum by utilizing the seismic stratum interface calibration result include:
Calibrating well point seismic stratum results aiming at a well earthquake combined target layer, and summarizing the reflection characteristics of the target layer seismic reflection phase-axis wave group, wherein the reflection characteristics of the target layer seismic reflection phase-axis wave group comprise polarity, amplitude and continuity;
and (5) tracking, comparing and explaining by utilizing the reflection characteristics of the seismic wave groups of the seismic stratum.
6. An evaluation method for quantitatively characterizing the width of a fracture zone of an inverse fault as claimed in claim 5, characterized in that,
The specific steps for compiling the sensitive attribute plan by utilizing the interpreted seismic interface and the sensitive attribute include:
Extracting sensitive attribute values in a given time window by using a seismic interface, and averaging the attribute values in a limited time window to serve as sensitive attribute values A ij at coordinate points, wherein i and j are respectively the longitudinal grid counting points of the seismic grid;
Using the attribute value discrete point A ij, the earth coordinates at that point and the attribute value A ij are combined and meshed to form a sensitive attribute plane distribution map.
7. An evaluation method for quantitatively characterizing the width of a fracture zone of an inverse fault as claimed in claim 6, characterized in that,
The specific steps for compiling the distance from the break point to the break development probability curve graph according to the fault control point comprise the following steps:
On a sensitive attribute plane distribution diagram, P i is taken as a central point and is perpendicular to a fault plane, lmax/2 length is respectively taken at two sides of a fault control point, lmax is the maximum distance from the fault to the periphery adjacent fault, the center of a fault breakpoint is taken as an origin, the lower end of the fault is negative, the upper end of the fault is positive, m points are taken from an upper disc at a surface element interval, m is obtained by taking Lmax/2 and adding 1, and the sum is recorded as D ij, wherein i is E [1, n ], j is E [1, m ] n is the control point;
Respectively reading the sensitive attribute values of the upper disc layer and the lower disc layer, wherein each repeated point takes the maximum value of the sensitive attribute values as a discrete point D ij of the sensitive attribute value of the broken belt;
and respectively utilizing the discrete point data of the line segments perpendicular to the fault plane at N P i, taking the distance from the fault origin as a horizontal axis, taking the discrete point D ij of the sensitive attribute value of the fracture breaking zone as a vertical axis, and compiling a graph C i of the distance from the break point and the fracture development probability, wherein i is E [1, N ].
8. An evaluation method for quantitatively characterizing the width of a fracture zone of an inverse fault as claimed in claim 7,
The specific steps of obtaining the reverse fault fracture zone development curve by utilizing the separation point distance-fracture development probability curve graph include:
Overlapping N separation point distance-fracture development probability curves C i according to coordinates;
Analyzing the fluctuation trend of the N curves C i, and if a curve inconsistent with the overall trend exists, discarding the curve as an abnormal curve;
solving an average line C AVG of the residual break point distance-breaking development probability curve C i;
And carrying out median filtering on the C AVG to eliminate abnormal spike interference, wherein the filtered curve is the fracture zone development curve C of the reverse fault.
9. An evaluation method for quantitatively characterizing the width of a fracture zone of an inverse fault as claimed in claim 8, characterized in that,
The specific steps for acquiring the attribute value of the fault-free development influence area comprise the following steps:
Aiming at a well drilling area, a second derivative C '' is calculated by utilizing a fracture zone development curve of a reverse fault aiming at the well drilling area by taking a sensitive attribute of a fracture-free development part of a target layer as a fracture-free base value D 0, and a fracture development concentration degree change inflection point is represented;
a second derivative C '' graph is compiled, and the two sides of the upper and lower discs of the graph are in an oblique symmetrical state;
And calibrating a C curve point intersection point D 0 at the point of the C '' spike point, wherein the point represents the boundary of a fault development zone, and the fracture breaking zone is close to the center.
10. An evaluation method for quantitatively characterizing the width of a fracture zone of an inverse fault as claimed in claim 9,
The specific steps of obtaining the width value of the fracture zone of the fault fracture through the second derivative curve of the fracture development probability comprise the following steps: the distance from the upper disc D 0 and the lower disc D 0 of the reverse fault to the original point 0 is respectively read to obtain the width value of the broken belt of the upper disc and the lower disc of the fault, and the sum of the widths of the broken belts of the upper disc and the lower disc is the total width value of the broken belt of the fault.
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