A method for drawing fault polygonal planes by combining well-seismic analysis

Abstract

The present invention discloses a method for drawing a fault polygon plane by combining well-seismic data. This patented method projects the spatial position relationship and distance relationship between the stratigraphic comparison layer and the well-surface comparison breakpoint onto the plane map of the corresponding layer, uses the position relationship between the breakpoint and the layer to judge the validity of the fault multi-layer polygon, and uses the distance relationship between the breakpoint and the layer to control the specific position and shape of the fault polygon. First, a stratigraphic grid is established for the work area according to the needs, and the position of the well-surface geological stratification and breakpoints is determined by using geological research methods such as stratigraphic comparison; further, the position and distance relationship between the well-surface geological stratification and the relevant breakpoints are calculated, and the spatial position of the breakpoints is projected onto the plane map of the corresponding layer for quality control and verification of the drawing of the fault polygon of the layer. The fault polygon drawn by using this method is more accurate and reliable.

Description

Technical Field

[0001] The present invention relates to the field of seismic data interpretation, and in particular to a method for drawing a well-seismic combined fault polygonal plane. Background Art

[0002] In the current geological exploration and prospecting for oil and mineral deposits, the compilation of structural maps is a crucial task. This involves utilizing kinematic information such as seismic wave reflection time, phase instability, and wave velocity to study the distribution and undulation of stratigraphic interfaces and the development of faults. Travel times in seismic event profiles are converted into stratigraphic interface depths to create tectonic maps, providing data for the search for structural oil and gas reservoirs. The planar rendering of fault polygons is a crucial component of this process, as their accuracy directly impacts the accuracy of the structural map, which in turn directly impacts the accurate identification of traps and reservoirs. Therefore, precise and accurate fault polygon rendering is crucial. Fault interpretation using seismic data is highly ambiguous, and the location of faults is subject to significant subjective influence. The precise shape and location of fault polygons on planar maps are difficult to determine. Therefore, geological knowledge, such as stratigraphic correlation results, is often used as a constraint to aid in the rendering of fault polygons.

[0003] The existing method uses stratigraphic correlation results to constrain fault polygon drawing. Specifically, if a layer point exists for the corresponding layer on the well, the spatial location of that layer point is projected onto the plan view of that layer to indicate it is a layer. If the layer point is lost during stratigraphic correlation, the location of the nearest geological layer point above it is projected onto the plan view to indicate it is lost. Furthermore, the display markers on the plane guide and verify the drawing of the fault polygon on the plane. The quality control method is to ensure that the layer marker cannot fall within the fault polygon, and the lost marker cannot fall outside the multi-layer polygon. This method can ensure the validity of fault polygon deformation, but it does not provide specific guidance for the drawing of the fault polygon.

[0004] Figure 1The geological information used in conventional well-seismic fault polygon mapping includes the coordinate projections of S25 for the three vertical wells Wa, Wb, and Wc, and the missing marker "F" placed at S24 for Well Wd. Based on conventional display information and quality control criteria, the coordinate projections of S25 for Wells Wa, Wb, and Wc must be outside the fault polygon, and the missing marker "F" for Well Wd must also be outside the fault polygon. The existing solution A only satisfies the requirement that the geological stratification be outside the fault polygon, but the missing marker "F" for Well Wd does not satisfy the requirement that it be inside the fault polygon. Therefore, Solution B is more "reasonable" than Solution A. The trajectory of Well Wd shows that the planar projection of the fault breakpoint on Well Wd is located at position Fd, which means that breakpoint Fd should be inside the fault polygon. Therefore, although Solution B, obtained using conventional well-seismic constraints and criteria, is more reasonable, it incorrectly applies the location information of the missing marker "F" for the deviated well. Therefore, Solution A is more reasonable overall.

[0005] Traditional well-seismic constraint information cannot effectively guide the drawing of fault polygons. There are two main reasons: first, the constraint scheme does not fully utilize the relative position and distance information between the stratification points and the breakpoints. The constraint conditions are too loose, which will cause multiple solutions for the drawing of fault polygons; second, the error in the projection position of the missing marker of the inclined well fault causes inaccurate fault polygon drawing. Summary of the Invention

[0006] The purpose of the present invention is to solve at least one of the technical problems existing in the prior art and to provide a method for drawing fault polygon planes by combining well-seismic analysis, which can draw fault polygons more accurately and reliably.

[0007] According to a first aspect of the present invention, a method for drawing a fault polygonal plane by combining well-seismic analysis is provided, comprising the following steps:

[0008] According to the research accuracy requirements, a geological stratification framework is established for the work area, and the geological stratification layers are defined as H1, H2…Hn…HN,

[0009] Where, 1≤n≤N, N is the number of geological layers in the stratigraphic framework;

[0010] Obtain the geological stratification layer and breakpoint position on the well based on stratigraphic comparison;

[0011] Determine the horizon for drawing the fault polygon;

[0012] Calculate the relationship between the geological stratification and related breakpoints of the well;

[0013] Projecting the relationship information between the horizon and the breakpoint and the inherent information of the breakpoint onto the plane map at the breakpoint position;

[0014] Use the information on the plan view as constraints to draw and verify the fault polygons.

[0015] According to the first aspect of the present invention, projecting the relationship information between the horizon and the breakpoint and the inherent information of the breakpoint onto the plan view at the breakpoint position specifically includes:

[0016] The relationship between all the upper layers Hn and the relevant breakpoints Fni is used as additional constraint information, and the inherent information of the relevant breakpoints Fni is projected onto the plane map of the layer Hn according to the spatial position of the relevant breakpoints to guide the drawing of the fault polygon of the layer Hn, where ni is a positive integer greater than or equal to 1.

[0017] According to the first aspect of the present invention, the inherent information of the breakpoint and the additional constraint information are distinguished by using special symbols in combination with different positions.

[0018] According to the first aspect of the present invention, the relevant breakpoint is the breakpoint between point Dt and point Db on well W, including Dt and Db.

[0019] The Dt point is determined as follows:

[0020] If there is a nearest geological stratification point Hnt (1≤nt<n) above Hn, then Dt is the geological stratification point Hnt;

[0021] If there is no stratigraphic correlation geological layering point Hnt above Hn, and the first point with the shallowest measured depth in the stratigraphic correlation is the breakpoint Ffist, then Dt is Ffist;

[0022] If conditions A and B are not met and Hn exists in the stratigraphic correlation, then Dt is Hn;

[0023] If conditions A, B, and C are not met, there is a situation where the horizon Hn is missing but there is no fault. The stratigraphic correlation results should be re-confirmed or the correlation results of the well should be ignored.

[0024] The Db point is determined as follows:

[0025] If there is a nearest geological layer point Hnb below Hn, then Db is the geological layer point Hnb;

[0026] If there is no geological layer point Hnb below Hn, the last breakpoint on the well is taken as Db;

[0027] If conditions A and B are not met and Hn exists in the stratigraphic comparison, and the deepest last breakpoint Flast exists in the stratigraphic comparison, then Db is Flast;

[0028] If conditions A, B, and C are not met, there is a situation where the layer Hn is missing but there is no correlation breakpoint. The stratigraphic correlation results should be re-implemented or the correlation results of the well should be ignored.

[0029] According to the first aspect of the present invention, the relationship information between the geological stratification points and the related breakpoints specifically includes:

[0030] If Hn is in stratigraphic correlation and Fni is located above Hn, the relationship between the two is expressed by the "above position distinguishing symbol" and the sounding distance "len" between the two;

[0031] If Hn exists in the stratigraphic comparison and Fni is located below Hn, the relationship between the two is expressed by the "below position distinguishing symbol" and the sounding distance "len" between the two;

[0032] If Hn does not exist in the stratigraphic correlation, the relationship between the two is expressed by the "stratigraphic missing relationship symbol".

[0033] According to the first aspect of the present invention, the "upper position distinguishing symbol" includes the symbol "+", the "lower position distinguishing symbol" includes the symbol "-", and the "stratum missing relationship symbol" includes "0";

[0034] According to the first aspect of the present invention, the inherent information of the breakpoint Fni includes at least one of the depth information of the breakpoint, the well information to which the breakpoint belongs, and the formation dip information at the breakpoint.

[0035] According to the first aspect of the present invention, the control method for guiding the drawing of the fault polygon of the horizon Hn is as follows:

[0036] The inherent information of the breakpoint is used to determine the fault polygon to which the breakpoint belongs;

[0037] Use the additional information of the breakpoints to constrain the position of the fault polygon as follows:

[0038] If the breakpoint Fni is located below Hn, the breakpoint is located in the descending disk direction of the fault polygon;

[0039] If the breakpoint Fni is above Hn, the breakpoint is located in the ascending disk direction of the fault polygon;

[0040] Otherwise the breakpoint is inside the fault polygon.

[0041] The embodiments of the present invention have at least the following technical effects:

[0042] The embodiment of the present invention projects the spatial position relationship and distance relationship between the stratigraphic comparison layer and the wellbore comparison breakpoint onto the plan view of the corresponding layer, uses the position relationship between the breakpoint and the layer to judge the validity of the fault multi-layer polygon, and uses the distance relationship between the breakpoint and the layer to control the specific position and shape of the fault polygon, so that the drawn fault polygon is more reasonable and accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The present invention will be further described below with reference to the accompanying drawings and embodiments;

[0044] Figure 1 Two fault polygon schemes drawn based on traditional constraint methods in the prior art;

[0045] Figure 2 This is a flow chart of a method for drawing a fault polygonal plane by combining well-seismic analysis according to an embodiment of the present invention;

[0046] Figure 3 Schematic diagram of geological stratification points, breakpoints, additional constraint information, and distances between stratification points and breakpoints for different wells in an embodiment of the present invention;

[0047] Figure 4 Schematic diagram of the plane positions of different wells and the trajectory information of inclined wells in an embodiment of the present invention;

[0048] Figure 5 This is a fault polygon scheme drawn according to the constraint method of the present invention in an embodiment of the present invention. DETAILED DESCRIPTION

[0049] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it should not be understood as a limitation on the scope of protection of the present invention.

[0050] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention 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. Therefore, they cannot be understood as limitations on the present invention.

[0051] Reference Figure 2 The present invention provides a method for drawing a fault polygonal plane by combining well-seismic data, comprising the following steps:

[0052] Step 110 , a geological stratification grid is established for the work area according to the research accuracy requirement, and the geological stratification points are defined as H1, H2…Hn…HN, where 1≤n≤N, and N is the number of geological strata in the stratigraphic grid.

[0053] Step 120: Obtain the geological stratification points and breakpoint positions on the well based on stratigraphic comparison.

[0054] Step 130: Determine the layering points for drawing the fault polygon.

[0055] Step 140: Calculate the relationship information between the geological stratification points of the layer on the well and the related breakpoints.

[0056] In this embodiment, the relevant breakpoint is the breakpoint between point Dt and point Db on well W, including Dt and Db.

[0057] The Dt point is determined as follows:

[0058] If there is a nearest geological stratification point Hnt (1≤nt<n) above Hn, then Dt is the geological stratification point Hnt;

[0059] If there is no stratigraphic correlation geological layering point Hnt above Hn, and the first point with the shallowest measured depth in the stratigraphic correlation is the breakpoint Ffist, then Dt is Ffist;

[0060] If conditions A and B are not met and Hn exists in the stratigraphic correlation, then Dt is Hn;

[0061] If conditions A, B, and C are not met, there is a situation where the horizon Hn is missing but there is no fault. The stratigraphic correlation results should be re-confirmed or the correlation results of the well should be ignored.

[0062] The Db point is determined as follows:

[0063] If there is a nearest geological layer Hnb below Hn, then Db is the geological layer point Hnb;

[0064] If there is no geological layer point Hnb below Hn, the last breakpoint on the well is taken as Db;

[0065] If conditions A and B are not met and Hn exists in the stratigraphic comparison, and the deepest last breakpoint Flast exists in the stratigraphic comparison, then Db is Flast;

[0066] If conditions A, B, and C are not met, there is a situation where the layer Hn is missing but there is no correlation breakpoint. The stratigraphic correlation results should be re-implemented or the correlation results of the well should be ignored.

[0067] In this embodiment, the relationship information between the geological stratification points and the related breakpoints specifically includes:

[0068] If Hn is in stratigraphic correlation and Fni is located above Hn, the relationship between the two is expressed by the "above position distinguishing symbol" and the sounding distance "len" between the two;

[0069] If Hn exists in the stratigraphic comparison and Fni is located below Hn, the relationship between the two is expressed by the "below position distinguishing symbol" and the sounding distance "len" between the two;

[0070] If Hn does not exist in the stratigraphic correlation, the relationship between the two is expressed by the "stratigraphic missing relationship symbol".

[0071] As an example of an embodiment of the present invention, the "upper position distinguishing symbol" is the symbol "+", the "lower position distinguishing symbol" is the symbol "-", and the "stratum missing relationship symbol" is the symbol "0".

[0072] Step 150: Project the relationship information between the horizon and the breakpoint and the inherent information of the breakpoint onto the plan view at the breakpoint position.

[0073] Specifically, the relationship between all the upper layer sites Hn and the relevant breakpoints Fni is used as additional constraint information, and the inherent information of the relevant breakpoints Fni is projected onto the plan view of the layer site Hn according to the spatial position of the relevant breakpoint to guide the drawing of the fault polygon of the layer site Hn, where ni is a positive integer greater than or equal to 1.

[0074] It is understandable that the inherent information of the breakpoint and the additional constraint information are distinguished by special symbols in combination with different positions. The inherent information of the breakpoint includes at least one of the depth information of the breakpoint, the well information to which the breakpoint belongs, and the formation dip information at the breakpoint.

[0075] Step 160, using the information on the plan view as constraints, draw and verify the fault polygon.

[0076] Specifically, the control method for drawing the fault polygon of the horizon Hn is as follows:

[0077] The inherent information of the breakpoint is used to determine the fault polygon to which the breakpoint belongs;

[0078] Use the additional information of the breakpoints to constrain the position of the fault polygon as follows:

[0079] If the breakpoint Fni is located below Hn, the breakpoint is located in the descending disk direction of the fault polygon;

[0080] If the breakpoint Fni is above Hn, the breakpoint is located in the ascending disk direction of the fault polygon;

[0081] Otherwise the breakpoint is inside the fault polygon.

[0082] The additional fault information is the fault distance information for that fault point. The closest distance between the fault point Fni and the fault polygon is related to the fault dip at the fault point Fni, the trajectory of the well where the fault point Fni is located, and the distance between Fni and Hn. Generally, it can be qualitatively assumed that the distance between the fault point Fni and the fault polygon is positively correlated with the distance between the fault point Fni and the delamination point Hn.

[0083] As a specific example of the present invention, first, according to Figure 2 The well seismic combined with fault polygonal plane drawing method process shown in the figure establishes the work area stratification grid, determines the position of the well layers and breakpoints, and obtains the S24, S25, and S26 stratification points and breakpoint data of the four wells Wa, Wb, Wc, and Wd. The position relationship between the stratification points and the breakpoints, the placement information of the breakpoints on the S25 plane, and the distance information between the breakpoints and the layer S25 are shown in the figure. Figure 2 As shown, Wa, Wb, and Wc are vertical wells, and Wd is an inclined well. The well trajectories and the plane projection positions of the geological stratification points S24, S26, and the breakpoint Fd are shown in FIG. Figure 3 Now draw the plane fault polygon of layer S25.

[0084] like Figure 3 As shown, the additional constraint information of the breakpoints in the figure and the inherent information of the breakpoints can be expressed in the following format "F100|-60", where "F" represents the breakpoint information related to the layer, "100" is the inherent break information of the breakpoint, that is, the inherent information, "|" is used to separate the inherent information and constraint information of the fault, "-" indicates that the breakpoint related to the layer is located below the stratification point, and when the breakpoint is above the fault, it is "+", and the "+" symbol can be omitted. "60" represents the distance between the stratification point and the breakpoint. When the corresponding layer is missing, the breakpoint constraint information should be the stratum missing symbol "0", and the stratum data delivery format is as follows: "S25" where "S" is the corresponding geological stratum name.

[0085] The results of the well-seismic combined fault polygon drawing method according to the embodiment of the present invention are as follows: Figure 5 As shown, the breakpoint throws of wells Wa, Wb, Wc, and Wd are 100, 110, 105, and 120 meters, respectively. These throws are comparable and therefore indicate that they are breakpoints on the same fault. The position and distance information between the breakpoints Wa and Wb and the delamination point are "-60" and "-100," respectively. Therefore, the projections of Fa and Fb should be located on the downthrown side of the fault polygon, with the closest distances to the downthrown side being approximately 60 and 100 meters. The position and distance information between the breakpoint Wc and the delamination point is "110," indicating that the projection should be located on the upthrown side of the fault, with the closest distance to the upthrown side being approximately 110 meters. The projection of well Wd is the projection of breakpoint Fd and is located within the fault polygon.

[0086] Figure 5 The constraint method shown can determine the approximate position of the fault line between the upper and lower walls of the fault polygon based on the positional relationship between the stratification points and the relevant breakpoints, and the specific shape and position of the fault line can be determined based on the distance information; at the same time, the display position of the fault missing mark is more accurate, and the drawn fault polygon is more reasonable.

[0087] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by ordinary technicians in the technical field without departing from the scope of the present invention.

Claims

1. A method for drawing a fault polygonal plane by combining well-seismic data, characterized in that: The following steps are involved: A geological stratification framework for the work area is established according to the requirements of research accuracy, and geological stratification points are defined as H1, H2…Hn…HN, where 1≤n≤N, and N is the number of geological strata in the stratigraphic framework; geological stratification points and breakpoint positions on the well are obtained based on stratigraphic comparison; the layer for drawing the fault polygon is determined; the relationship information between the geological stratification points at this layer on the well and the relevant breakpoints is calculated, where the relationship information includes spatial position relationship and distance relationship; the relationship information between the stratification point and the breakpoint and the inherent information of the breakpoint are projected onto the plane map at the breakpoint position; the information on the plane map is used as a constraint to draw and verify the fault polygon; the relevant breakpoint is the breakpoint between point Dt and point Db on well W, including Dt and Db, where point Dt is determined as follows: A. If there is a nearest stratigraphic comparison geological stratification point Hnt above Hn (1≤nt<n), then Dt is the geological stratification point Hnt; B. If there is no stratigraphic stratification point Hnt above Hn, and the first point with the shallowest depth in the stratigraphic comparison is the breakpoint Ffist, then Dt is Ffist; C. If conditions A and B are not met and Hn exists in the stratigraphic comparison, then Dt is Hn; If conditions A, B, and C are not met, then there is a missing horizon corresponding to the stratification point Hn but no fault exists. Re-confirm the stratigraphic comparison results or ignore the comparison results of the well; the determination of point Db is as follows: A. If If the nearest geological stratification point Hnb exists below Hn, then Db is the geological stratification point Hnb; B. If there is no geological stratification point Hnb below Hn, then the last breakpoint on the well is taken as Db; C. If conditions A and B are not met and Hn exists in the stratigraphic comparison, and the last breakpoint with the deepest sounding in the stratigraphic comparison, Flast, exists, then Db is Flast; if conditions A, B and C are not met, then the corresponding horizon of the stratification point Hn is missing but there is no comparison breakpoint. In this case, the stratigraphic comparison results should be re-confirmed or the comparison results of the well should be ignored.

2. The method for drawing a polygonal plane of a fault by combining well-seismic analysis according to claim 1, characterized in that: The projecting of the relationship information between the stratification point and the breakpoint and the inherent information of the breakpoint onto the plan view at the breakpoint position specifically includes: using the relationship between all the stratification points Hn on the well and the related breakpoints Fni as additional constraint information and projecting the inherent information of the related breakpoints Fni onto the plan view of the stratification point Hn according to the spatial position of the related breakpoint, to guide the drawing of the fault polygon of the layer corresponding to the stratification point Hn, where ni is a positive integer greater than or equal to 1.

3. The method for drawing a polygonal plane of a fault by combining well-seismic analysis according to claim 2, characterized in that: The inherent information of the breakpoint and the additional constraint information are distinguished by using special symbols in combination with different positions.

4. The method for drawing a polygonal plane of a fault by combining well-seismic analysis according to claim 2, characterized in that: The relationship information between the geological stratification point and the relevant breakpoint specifically includes: if Hn exists in the stratigraphic comparison and Fni is located above Hn, the relationship between the two is expressed by an "upper position distinguishing symbol" and the sounding distance "len" between the two; if Hn exists in the stratigraphic comparison and Fni is located below Hn, the relationship between the two is expressed by a "lower position distinguishing symbol" and the sounding distance "len" between the two; if Hn does not exist in the stratigraphic comparison, the relationship between the two is expressed by a "stratum missing relationship symbol".

5. The method for drawing a polygonal plane of a fault combining well-seismic analysis according to claim 4, characterized in that: The "upper position distinguishing symbol" includes the symbol "+", the "lower position distinguishing symbol" includes the symbol "-", and the "stratum missing relationship symbol" includes "0".

6. The method for drawing a polygonal plane of a fault combining well-seismic analysis according to claim 2, characterized in that: The inherent information of the breakpoint Fni includes at least one of the depth information of the breakpoint, the well information to which the breakpoint belongs, and the formation dip information at the breakpoint.

7. The method for drawing a polygonal plane of a fault combining well-seismic analysis according to claim 6, characterized in that: The control method for guiding the drawing of the fault polygon corresponding to the layer point Hn is as follows: the inherent information of the breakpoint is used to determine the fault polygon to which the breakpoint belongs; the additional information of the breakpoint is used to constrain the position of the fault polygon, as follows: if the breakpoint Fni is below Hn, the breakpoint is located in the descending direction of the fault polygon; if the breakpoint Fni is above Hn, the breakpoint is located in the ascending direction of the fault polygon; otherwise, the breakpoint is located inside the fault polygon.

Images