阅读说明：本技术 走滑断裂体系的拓扑分析方法 (Topology analysis method of sliding fracture system ) 是由 邓尚 李兵 张继标 曹立迎 顾浩 于 2019-02-27 设计创作，主要内容包括：本发明提供的一种走滑断裂体系的拓扑分析方法以拓扑学理论为基础,基于断裂网络精细解释,厘定断裂网络中的节点类型和断裂线段分布等拓扑学基本要素,计算连通性节点的密度以及断裂线段的面密度,绘制等值线图。该方法可广泛运用于定量评价盆地地下走滑断裂体系断裂密度与连通性,解决了扫描线法不能反映断裂密度在平面内整体分布的非均值性和无法评价断裂连通性的问题,对于研究碳酸盐岩走滑断裂体系中的储层发育有利部位以及油气运聚具有重要意义。(The invention provides a topological analysis method of a sliding fracture system, which is based on a topological theory and based on the fine explanation of a fracture network, determines the topological basic elements such as node types and fracture line distribution in the fracture network, calculates the density of connected nodes and the surface density of fracture line segments, and draws a contour map. The method can be widely applied to quantitative evaluation of fracture density and connectivity of the basin underground sliding fracture system, solves the problems that the scanning line method cannot reflect the non-mean property of the overall distribution of the fracture density in a plane and cannot evaluate the fracture connectivity, and has important significance for researching favorable reservoir development parts and oil and gas migration and aggregation in the carbonate sliding fracture system.)

1. A topology analysis method of a sliding fracture system is characterized by comprising the following steps:

s1: defining nodes and broken line segments in a broken network in the research area according to the three-dimensional seismic data in the research area;

s2: and obtaining density distribution reflecting the variation trend of the fracture network density degree in the research area according to the nodes and the fracture line segments.

2. The topology analysis method of claim 1, wherein the density distribution comprises an areal density of broken line segments and/or a density of connectivity nodes.

3. The topology analysis method according to claim 2, wherein in step S2, the density of the connectivity nodes is obtained according to the connectivity nodes in the broken network.

4. The topology analysis method according to claim 3, wherein in step S2, the type of the node is determined by the fragmentation and truncation relationship, and then the connectivity node is identified by the type of the node.

5. The topology analysis method of claim 4, wherein the node types include X-type nodes, Y-type nodes, and I-type nodes;

the X-type node and the Y-type node are the connectivity nodes;

the type I node is a non-connectivity node.

6. The topology analysis method of claim 5, wherein the node types further comprise type V nodes, the type V nodes being the connectivity nodes.

7. The topology analysis method according to claim 2, wherein the areal density of the broken line segments is obtained from the lengths of the broken line segments.

8. The topology analysis method according to claim 1, wherein in step S1, a fracture distribution map in a study area is drawn according to the three-dimensional seismic data, and a node and fracture line segment distribution map is drawn according to the fracture distribution map.

9. The topology analysis method of any of claims 1-8, wherein a nuclear density analysis method is used to obtain a density distribution of the region of interest.

10. The topology analysis method according to any one of claims 1 to 8, wherein in step S1, the three-dimensional seismic data is a seismic coherence attribute map.

Technical Field

The invention belongs to the field of geological structure analysis, and particularly relates to a topological analysis method of a sliding fracture system.

Background

The sliding fracture refers to fracture generated by relative horizontal motion of the two fault discs under the action of couple of force of the earth crust under the action of shearing stress, the two fault discs do not vertically move, and because the fault plane moves in the horizontal direction, no obvious cliff is usually observed in field observation, and a fracture line appears on the ground.

Small scale glide slope in Kelamong usually does not exceed several kilometers (Man P. Global positioning, classification and technical orientations of recovery-and refining standards on active and equilibrium structure-slip fault systems [ J ]. Geological Society, London, specific Publications,2007,290(1):13-142), is a widely developed structure inside the Basin region (Deng S. structural characterization of interfacial structure-slip fault inter-level root [ J ]. AAPG Bulletin, 2019, 103(1), 109-137.). Research has shown that glide fractures can develop densely and form a fracture network in a staggered manner in a deep carbonate formation of a basin, the development density (fracture density for short) and connectivity of the fracture network can have important influence on the formation of a carbonate reservoir and the transportation and accumulation of oil and gas (Deng Shang et al. Tanlimu basin northward and neighboring trunk glide fracture zone differential activity characteristics and their relation to oil and gas enrichment [ J ] oil and gas geology 2018,39(5): 878-.

Analysis of fracture density and connectivity for walking and sliding fractures is a technical difficulty in this field, and a common method for analyzing fracture density at present is the scanning line method (De Journal G, Aydin A. the evaluation of the damagezone with failure growth in sandstone and materials multiscale characterization [ J ]. Journal of geographic Research Solid Earth,2007,112 (B12)). The method comprises spreading one or more measuring lines on the outcrop surface or the measuring surface in parallel or in multiple directions, recording the number of fractures intersected with the scanning lines, counting the numerical variation of the fracture number (frequency) along different scanning lines, and calculating the fracture line density.

Although the method provides an effective mathematical tool for researching the development intensity of fracture, the analysis method is single, the non-mean property of the overall distribution of the fracture density in a plane cannot be reflected, a uniform quantitative standard is difficult to provide for the density change of different parts of a sliding fracture system in the same research area, and the change of attributes such as fracture connectivity cannot be reflected.

Disclosure of Invention

In order to solve the technical problem in the existing method, the invention provides a topological analysis method of a sliding fracture system, which comprises the following specific scheme:

a topology analysis method of a sliding fracture system comprises the following steps:

s1: defining nodes and broken line segments in a broken network in the research area according to the three-dimensional seismic data in the research area;

s2: and obtaining density distribution reflecting the variation trend of the fracture network density degree in the research area according to the nodes and the fracture line segments.

Further, the density distribution includes an area density of broken line segments and/or a density of connected nodes.

Further, in step S2, the density of the connectivity nodes is obtained according to the connectivity nodes in the broken network.

Further, in step S2, the type of the node is determined by the fragmentation and truncation relationship, and then the connectivity node is identified by the type of the node.

Further, the node types comprise an X-type node, a Y-type node and an I-type node;

the X-type node and the Y-type node are the connectivity nodes;

the type I node is a non-connectivity node.

Further, the node types further include a V-type node, and the V-type node is a connectivity node.

Further, the surface density of the broken line segments is obtained according to the lengths of the broken line segments.

Further, in step S1, a fracture distribution map in the research area is drawn according to the three-dimensional seismic data, and a node and fracture line segment distribution map is drawn according to the fracture distribution map.

Further, a nuclear density analysis method is used to obtain the density distribution of the research area.

Further, in step S1, the three-dimensional seismic data is a seismic coherence attribute map.

Compared with the prior art, the invention provides a topological analysis method of a sliding fracture system, which divides an intricate and complex fracture network into a topological structure formed by nodes and fracture line segments, and can obtain density distribution reflecting the variation trend of the fracture network density degree in a research area according to the nodes and the fracture line segments, thereby solving the technical problem that the scanning line method in the prior art cannot reflect the non-mean value of the overall distribution of the fracture density in a plane.

Drawings

The invention will be described in more detail hereinafter on the basis of embodiments and with reference to the accompanying drawings. Wherein:

FIG. 1 is a fracture distribution plot of a region showing a fracture network within the region in an embodiment of the present invention;

FIG. 2 is a diagram of node types and broken line segments divided on the basis of FIG. 1;

FIG. 3 is a flowchart of a topology analysis method in an embodiment of the present invention;

FIG. 4 shows a Torpotabei and Torpotanan three-dimensional Torpotal 39 fragmentation system T in an embodiment of the present invention₇ ⁶An interface coherence attribute map;

FIG. 5 is a graph showing a fracture distribution obtained by a fine interpretation of the fracture of the Torpol 39 fracture system in an example of the present invention;

FIG. 6 is a graph showing the distribution of Torpol 39 fragmentation system nodes and fragmentation line segments, in accordance with an embodiment of the present invention;

FIG. 7 is a graph showing the distribution of the surface density of broken line segments of Topu 39 fracture system, wherein the variation of the surface density of the broken line segments is identified by color scale comparison in the example of the present invention;

FIG. 8 is a graph showing a density distribution of connectivity nodes in Topu 39 fracture system, where the density change of the connectivity nodes is identified by color scale comparison according to an embodiment of the present invention;

FIG. 9 is a graph of the surface density of a fracture line segment of the Topu 39 fracture system compared to the single well productivity (cumulative oil production), and the productivity is identified by color scale comparison in accordance with an embodiment of the present invention;

FIG. 10 is a graph comparing the density of connected nodes and the distribution of connected well groups in the Torpu 39 fracture system in the example of the present invention.

In the drawings, like reference numerals are used for like reference numerals, and the drawings are not drawn to scale.

Detailed Description

The invention will be further described with reference to the accompanying drawings.

The embodiment provides a topology analysis method of a sliding fracture system, which is based on topology, provides an effective method for analyzing fracture density and connectivity, and solves the problems that the non-mean property of the overall distribution of the fracture density in a plane cannot be reflected and the connectivity cannot be quantitatively analyzed.

Topology is an important, fundamental branch of mathematics. It was originally a branch of geometry, investigating the property of a geometric figure that remains unchanged under continuous deformation, i.e. continuous deformation, in the form of allowing deformations such as stretching and twisting, but not cutting and gluing, and has now developed into a mathematical branch investigating the continuity phenomenon.

Because the dip angle is approximately 90 degrees, the fracture network can be approximately a two-dimensional fracture network in a three-dimensional space. Nodes and segments are the topological primitives that make up any two-dimensional network (Sanderson D J, Nixon CW. the use of topology in fractional network topology [ J ]. Journal of structural geography 2015,72: 55-66). Any fracture network has geometrical characteristics (such as fracture trend and tendency) changed in continuous deformation, and the number of nodes and the proportion of specific node types in all nodes are not changed, so that the fracture network is a topological characteristic.

The embodiment provides a topology analysis method of a sliding fracture system, and the basic principle of the topology analysis method is shown in fig. 1 and fig. 2.

Acquiring fracture distribution in a certain area, as shown in fig. 1, the fracture distribution can be obtained by interpreting fractures through a seismic coherence attribute diagram and defining nodes and fracture line segments in a fracture network. The fracture network is formed by interweaving fracture lines, and nodes are usually the intersection points of the fracture lines or the end points of the fracture lines in the fracture network. The fracture line segment can be determined according to practical considerations, for example, only one parameter of the area density of the fracture line segment is obtained in a certain analysis, and the connectivity problem of the fracture is not discussed for a while, in this case, the fracture line segment can be selected from a segment between two adjacent nodes on the fracture line, for example, the segment between the node P1 and the node P2 in fig. 2 is the fracture line segment, or can be a segment between two nodes spaced on the fracture line, for example, in fig. 2, although the node P4 is still located between the nodes P3 and P5 on the fracture line, the segment between the nodes P3 and P5 can be divided into the fracture line segments, which is possible when only the area density parameter of the fracture is obtained without considering the connectivity problem of the fracture. After the fracture network is divided into the topological structure of nodes and fracture line segments, the length of each fracture line segment is known, the surface density of the fracture line segment is obtained by calculating the length of the fracture line in unit area, and the density of fractures is reflected by the density of the fractures on the plane.

Furthermore, when the connectivity problem of the sliding fracture system is considered, a section of fracture line between two adjacent nodes on the fracture line is taken as a fracture line section, and nodes are not included between the nodes at two ends of the fracture line section. Therefore, the connectivity of the node is convenient to judge. For example, the break line between the node P3 and the node P5 must be divided into a break line segment between the node P3 and the node P4 and a break line segment between the node P4 and the node P5, i.e., the break line between the node P3 and the node P5 cannot be regarded as a break line segment.

A connectivity node refers to a node that connects multiple fracture line segments, i.e., the node is a common endpoint for the multiple fracture line segments. For example, the node type is determined according to the fracture staggering and truncation relation, and the connectivity of the node is judged according to the node type. Specifically, the fracture staggering means that fracture lines meet, and a node formed at the meeting is a common end point of four fracture line segments, such as a node P6 and a node P7 shown in fig. 2, and the node type is an X-type node. The truncation relationship refers to the intersection of the fracture lines, and the node formed at the intersection is the common end point of the three fracture line segments, such as the node P2, the node P4 and the node P5 shown in fig. 2, and the node type is a Y-type node. Both type X and type Y nodes belong to connectivity nodes.

As shown in FIG. 2, node P1 and node P3 are both non-common endpoints of a broken line segment, and the node is type I node and belongs to a non-connectivity node.

The density of the connectivity nodes can be obtained by calculating the number of the connectivity nodes in unit area, and the density of the connectivity nodes in a plane is quantitatively reflected, so that the connectivity degree of a walking and sliding fracture system is quantitatively reflected. The technical problems that the scanning line method in the prior art cannot reflect the connectivity change of the sliding fracture and cannot quantitatively evaluate the fracture connectivity are well solved. In addition, the density of the connectivity nodes is the number of the connectivity nodes in a unit area, belongs to the surface density, and can reflect the non-average value of the overall distribution of the density of the connectivity nodes in a plane.

Furthermore, the type of the broken line segment can be determined according to the types of nodes at two ends of the broken line segment, and the types of the broken line segment can be divided into the following types according to different node types:

I-I type, I-X type, I-Y type, Y-X type, and X-X type.

The type of the broken line segment has no direction difference, for example, type I-X and type X-I are broken line segments of the same type, type I-Y and type Y-I are broken line segments of the same type, and type Y-X and type X-Y are broken line segments of the same type.

Preferably, on the basis of the obtained finite number of density values (the area density of the broken line segments and the density of the connectivity nodes), the density value distribution of the whole research area can be obtained by a nuclear density analysis method.

Furthermore, the nodes and broken line segments of the broken network can be determined through the seismic coherence attribute graph to obtain the broken distribution graph shown in fig. 1, the node types and broken line segments shown in fig. 2 are compiled on the basis of fig. 1, the nodes in fig. 2 are divided into connected nodes and non-connected nodes according to the node types, and finally the node and broken line segment distribution graph is compiled. The node and the broken line segment distribution map are led into GIS (geographic Information System) software, so that the density of the connected nodes and the surface density of the broken line segments can be calculated, contour lines are drawn, and a broken line segment density distribution map and a density facet map of the connected nodes are derived.

In this embodiment, a topological analysis method is applied to analyze a topu 39 fracture system in a three-dimensional coverage area of a topu plateau of a Tarim basin, and the topu 39 fracture system is a sliding fracture system. In this embodiment, the area density of the broken line segment and the density of the connectivity node are analyzed at the same time, and the specific steps are as follows:

first, fine interpretation of fractures:

based on a high-precision earthquake three-dimensional extraction fracture main activity interface coherence attribute graph and an earthquake section, the fracture geometric morphology is finely explained, and fracture geometric characteristics are determined.

The main fracture active interfaces in the embodiment are the three-dimensional Topitotabei and the three-dimensional Topitota south (two three-dimensional splicing) T₇ ⁶Interface, T₇ ⁶The coherence properties of the interface are shown in figure 4.

On the basis of fig. 4, the fracture geometry is finely explained, and the geometric characteristics of the fracture are determined, thereby obtaining the fracture distribution map shown in fig. 5.

Secondly, determining the node type based on the fracture fine interpretation, fracture staggering and truncation relations of the Topu 39 fracture system, and drawing a fracture network node and line segment distribution diagram:

the broken line segments in fig. 5 are all broken lines between adjacent nodes.

The node type is determined according to the fracture staggering and truncation relation and the like, whether the node is a connectivity node or not is judged according to the node type, and finally a node and fracture line section distribution diagram compiled on the basis of the graph in fig. 5 is shown in fig. 6. The solid black dots in fig. 6 are connected nodes, and the open white dots are disconnected nodes. The hollow white points are I-type nodes, and the solid black points are mainly X-type nodes or Y-type nodes.

One more specific type of connectivity node is shown in FIG. 6, namely node P8, node P9, and node P10, whose node types are V-nodes, which are the common endpoints of two broken line segments.

This kind of connectivity node is special because, generally speaking, even if the broken line segment is already divided, theoretically any number of nodes can be added between the nodes at both ends, the broken line segment can be subdivided into any number of broken line segments, all the added nodes on the broken line segment are the common end points of two subdivided broken line segments, if this kind of node is divided into connectivity nodes, it means that there can be an infinite number of connectivity nodes on the divided broken line segment, and the density of connectivity nodes will be infinitely enlarged, which is obviously impractical.

For the processing of the situation, an X-type node, a Y-type node and an i-type node in a fracture network can be determined, and then, the fracture line segments divided by the three types of nodes are discussed in multiple situations, and whether a new V-type node needs to be added or not is judged:

(1) the divided broken line segments are straight lines;

in this case, a node connecting two subdivided broken line segments can be set at any position, the position of the subdivided node cannot be determined, and a new node is not required.

(2) The divided broken line segment is a curve with smooth transition;

in this case, the broken line segments are smoothly transited when the trend changes, and no new node is needed. The broken line segment between the node P11 and the node P12 in fig. 6 is a smooth transition curve, and no node is added.

(3) The divided broken line segments are formed by combining broken lines, and the included angle between two adjacent broken lines is obviously smaller than 180 degrees;

in this case, the intersection point of the two broken lines can be newly added as a node of the broken network, the node is a V-shaped node, and the V-shaped node subdivides the original broken line segment into two broken line segments. Such as node P8, node P9, and node P10 in FIG. 6

(4) The divided broken line segments are formed by combining broken lines, and the included angle of two adjacent broken lines is close to 180 degrees;

in this case, the two adjacent broken lines are similar to a straight line, and the intersection point of the two adjacent broken lines is newly added as a V-shaped node, or the node is not newly added.

(5) The divided broken line segments are composed of two folding lines and an arc transition line between the two folding lines;

in this case, the intersection point of the extension lines of the two folding lines or one point on the arc transition line may be newly added as the V-shaped node according to the size of the curvature radius, or the node may not be newly added.

In addition to the situation listed in the above point (3), the new V-type node setting has a larger free-form measure, and the V-type node in the broken network can be determined according to the actual situation in the application process. In other embodiments, when the newly added set of V-nodes is difficult to determine, the V-nodes can be ignored, i.e., the effect of the V-nodes on the connectivity analysis of the fractured system is not considered.

And thirdly, quantitatively analyzing the fracture connectivity and the fracture density distribution in the research area:

importing a node and broken line segment distribution diagram of a broken network for distinguishing connected nodes and non-connected nodes, namely figure 6 into GIS (geographic Information System) software, and calculating the density of the connected nodes and the surface density of broken line segments.

The GIS adopts a nuclear density analysis method to obtain the density distribution in the whole research area through a limited density value (the density of the connectivity nodes or a limited value of the surface density of the fracture line segments), and draws a contour map, wherein the obtained surface density distribution map of the fracture line segments of the Topu 39 fracture system is shown in FIG. 7, and the density distribution map of the connectivity nodes of the Topu 39 fracture system is shown in FIG. 8.

In FIG. 7, the area density of the fracture line at a certain position can be determined according to the comparison of the color of the position in the graph and the color scale at the lower right corner in the graph.

In fig. 8, the density of the connectivity nodes at a certain position can be determined according to the comparison of the color of the position in the graph and the color scale at the lower right corner in the graph.

The higher the surface density of the broken line segments and the density of the connected nodes, the more favorable the reservoir development and the oil gas enrichment are. Usually, a region with relatively high surface density of fracture line segments and relatively high density of connected nodes in a research region is selected as a potential favorable reservoir development part and a hydrocarbon enrichment region.

Specifically, in this embodiment, the surface density value of the selected fracture line segment is greater than 18.8 (m/m)²) And a density of connectivity nodes greater than 195 (pieces/m)²) As potentially beneficial reservoir development sites and hydrocarbon-rich zones.

The surface density of the fracture line segments and the density of the connectivity nodes shown in fig. 7 and fig. 8 simultaneously show that the topu 39 fracture splice segment and the northern fracture density in the research area are high, the connectivity is better, and the fracture splice segment is a potentially beneficial reservoir development part and a hydrocarbon enrichment area.

The existing well drilling in the Topu platform area reveals that the well groups with high productivity are mostly distributed in the area with high surface density of the Topu 39 fracture splice section and the northern fracture line section in the research area, as shown in FIG. 9, and the well groups in the area with high density of the connectivity nodes are mostly connected, as shown in FIG. 10, and the actual results shown in FIGS. 9 and 10 are consistent with the predicted results.

The colored points in FIG. 9 represent well locations, the color of the points represents the productivity of a single well, and the comparison of the color of a point to the color scale in the lower right corner of FIG. 9 indicates the productivity of the well represented by the point. The colors on the surface area of FIG. 9 represent the surface density of the fractured line segment, the distribution of which is consistent with that of FIG. 7, and the surface density value of the fractured line segment can be determined by comparing with the color scale at the lower right corner of FIG. 7.

The black dots in fig. 10 represent the connectivity nodes, the colors on the area represent the density of the connectivity nodes, the density of the connectivity nodes can be determined by comparing the color scale in the lower right corner of fig. 10, and the density distribution of the connectivity nodes in fig. 10 is consistent with fig. 8. The white crosses in fig. 10 represent well locations, and the white circles indicate portions of connected well groups.

Fig. 3 shows the whole flow of the topology analysis method of the above-described sliding fracture system of the present embodiment.

While the invention has been described with reference to a preferred embodiment, various modifications may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In particular, the various features mentioned in the various embodiments may be combined in any combination as long as there is no logical or structural conflict. It is intended that the invention not be limited to the particular embodiments disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.