Fire body depicting method based on multi-channel coherent reflection intensity slope attribute

Abstract

The invention discloses a method for depicting a fire body based on a multichannel coherent reflection intensity slope attribute. The method comprises the following steps: acquiring seismic geological section features corresponding to each geological layer of the fire body in a research area; depicting a volcano channel phase of the fire body in the research area and determining a development range of the volcano channel phase on the basis of the seismic geological section characteristics and the multiple coherent average energy slices of the fire body in the research area; the method effectively solves the problem that the existing volcanic rock mass recognition technology is slow in recognition speed and poor in recognition effect on the features of the fire mountain body structure.

Description

Technical Field

[0001] The present disclosure relates to the technical field of rock mass identification and characterization, and particularly to a method for characterizing volcanic bodies. Background Art

[0002] The statements in this section only provide background information related to the present disclosure and do not constitute prior art.

[0003] With the continuous increase in the current world's demand for oil and gas resources, the exploration and development of volcanic rock oil and gas reservoirs have gradually become new highlights for the growth of oil and gas reserves and production. Volcanic rock is a kind of magmatic rock formed after magma rises along fractures and erupts to the earth's surface through volcanic channels. Its structure and texture are quite complex, and it is difficult to identify its rock mass, which is also the difficulty in the current identification and characterization of volcanic rock masses.

[0004] Existing techniques for identifying volcanic rock masses usually use methods such as gravity and magnetic methods, seismic methods, conventional logging methods, geochemistry methods, neural network technology methods, and fuzzy mathematics methods to identify the lithology of volcanic rock masses. However, the formation of volcanic rocks is multi-periodic and the materials are diverse. It is difficult for existing techniques to quickly identify the volcanic source, and the identification effect of the structural characteristics of volcanic bodies is poor, resulting in inaccurate prediction of the reservoir characteristics and favorable facies belts of volcanic bodies.

[0005] It should be noted that the information disclosed in the above background art section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute prior art. Summary of the Invention

[0006] In view of this, the present disclosure provides a method for characterizing volcanic bodies based on the slope attribute of multi-channel coherent reflection intensity, which solves the problems that the current volcanic rock mass identification technology has a slow identification speed and a poor identification effect for the structural characteristics of volcanic bodies.

[0007] To achieve the above invention purpose, the method for characterizing volcanic bodies based on the slope attribute of multi-channel coherent reflection intensity includes:

[0008] Obtain the seismic-geological profile characteristics corresponding to each geological layer of the volcanic body in the study area;

[0009] Based on the seismic-geological profile characteristics and the multi-channel coherent average energy slice of the volcanic body in the study area, characterize the volcanic conduit facies of the volcanic body in the study area and determine the development range of the volcanic conduit facies.

[0010] In the present disclosure and possible embodiments, the method for determining each geological layer of the volcanic body in the study area includes:

[0011] Using the well logging data, logging data and 3D seismic data of the volcanic rocks in the study area, based on the lithological combination characteristics of the regional standard wells, and taking the electrical cycle characteristics as the basis, the gas reservoir groups in the volcanic bodies are divided by the combined logging curve characteristic comparison method. According to the division results, an isochronous stratigraphic correlation framework combining wells and seismic data in the study area is constructed, and each geological stratification of the volcanic bodies in the study area is determined through the isochronous stratigraphic correlation framework.

[0012] In the present disclosure and possible embodiments, the method for obtaining the seismic-geological profile characteristics corresponding to each geological stratification of the volcanic bodies in the study area includes:

[0013] Perform well-seismic stratification adjustment on each geological stratification of the volcanic bodies in the study area, calibrate the seismic stratification after adjustment, and determine the seismic-geological profile characteristics corresponding to each geological stratification of the volcanic bodies in the study area.

[0014] In the present disclosure and possible embodiments, the method for determining the seismic-geological profile characteristics corresponding to each geological stratification of the volcanic bodies in the study area includes:

[0015] According to the well-seismic combined cross-well profile, adjust the stratification depths between each geological stratification according to a unified stratification standard among wells to obtain the adjusted geological stratification;

[0016] Based on the seismic-geological profile and the drilling stratification results, use well logging information to perform artificial synthetic record calibration on the target wells in the adjusted geological stratification to obtain the seismic reflection wave group characteristics corresponding to each geological interface; according to the seismic reflection wave group characteristics, determine the seismic-geological profile characteristics corresponding to each geological stratification of the volcanic bodies in the study area.

[0017] In the present disclosure and possible embodiments, the method for depicting the volcanic conduit facies of the volcanic bodies in the study area and determining the development range of the volcanic conduit facies includes:

[0018] Based on the geological stratification of the volcanic bodies in the study area, use the volcanic crater profile interpretation technology to identify the volcanic crater profile, extract the profile characteristics of the volcanic conduit on the seismic-geological profile, and determine the location of the volcanic crater;

[0019] Obtain the coherence data volume of the geological stratification of the volcanic body, extract multi-channel coherent average energy slices from the coherence data volume, and obtain the planar distribution characteristics of the volcanic crater and the volcanic conduit through the multi-channel coherent average energy slices;

[0020] Based on the planar distribution characteristics of the crater and volcanic conduit, the cross-sectional characteristics of the volcanic conduit, and the location of the crater, three-dimensional visualization interpretation of the geological stratification of the volcanic body is carried out to obtain the spatial distribution characteristics of the crater and volcanic conduit, and the development range of the volcanic conduit facies is determined according to the spatial distribution characteristics of the crater and volcanic conduit.

[0021] In the present disclosure and possible embodiments, the method for depicting the volcanic body further includes:

[0022] Obtain the multi-channel coherent reflection intensity slope attribute of the volcanic body, and combine the seismic geological profile characteristics to determine the cross-sectional characteristics, planar characteristics, and main development location of the volcanic body in the study area.

[0023] In the present disclosure and possible embodiments, the method for determining the cross-sectional characteristics of the volcanic body includes:

[0024] Based on the characteristic data of the volcanic rock mass encountered in the known wells in the study area, horizon calibration of the volcanic rock mass is carried out on the seismic geological profile; based on the horizon calibration result of the volcanic rock mass, cross-sectional interpretation of the volcanic body is carried out, and the cross-section of the volcanic body is identified according to the reflection characteristic differences of the post-stack seismic profile, three-instant profile, and pure wave profile, and the cross-sectional characteristics of the volcanic body are obtained.

[0025] In the present disclosure and possible embodiments, the method for determining the planar characteristics and main development location of the volcanic body includes:

[0026] Perform extrapolation interpretation of the volcanic body plane on the cross-section of the volcanic body to obtain the planar characteristics of the volcanic body;

[0027] Perform multi-channel coherent reflection intensity slope slicing processing on the coherent data volume of the geological stratification of the volcanic body to obtain the multi-channel coherent reflection intensity slope attribute of the volcanic body;

[0028] Combine the cross-sectional characteristics and planar characteristics of the volcanic body, identify the volcanic body on the seismic geological profile, and refer to the multi-channel coherent reflection intensity slope attribute, and combine the seismic reflection characteristics of the profile to determine the main development location of the volcanic body.

[0029] In the present disclosure and possible embodiments, the method for depicting the volcanic body further includes:

[0030] Carry out effective reservoir prediction on the geological stratification of the volcanic body to obtain effective reservoir prediction results;

[0031] Based on the development range of the volcanic conduit facies and the main development location of the volcanic body, and in combination with the effective reservoir prediction results, the volcanic body is divided into crater - near-crater facies, near-source facies, and far-source facies to determine the development range of the volcanic facies belt in the study area.

[0032] In the present disclosure and possible embodiments, the method for depicting a volcanic body further includes:

[0033] According to the single-well facies division result of the volcanic body in the study area, in combination with the multi-channel coherent reflection slope intensity slice, the distribution areas of the explosive facies and the overflow facies are depicted within the proximal facies, and multi-attribute clustering analysis is performed in combination with the sensitive attributes of the volcanic rock facies to depict the planar facies belt of the volcanic rock in the study area.

[0034] In the present disclosure and possible embodiments, the method for performing multi-attribute clustering analysis to depict the planar facies belt of the volcanic rock in the study area includes:

[0035] The multi-attribute clustering analysis is performed using the attribute waveform clustering method. By using the attribute waveform clustering method, the planar facies of the volcanic rock corresponding to each target layer and the single well of the volcanic body are divided in the geological stratification;

[0036] Based on the planar facies of the volcanic rock, the optimization of the planar Seino waveform clustering parameters and the extraction of clustering attributes are performed. By using the planar sensitive attributes of the Seino waveform clustering and combining the single-well gas testing productivity of the volcanic body, the facies belts starting with the explosive facies and the facies belts starting with the overflow facies are depicted within the distribution areas of the explosive facies and the overflow facies;

[0037] Based on the facies belts starting with the explosive facies and the facies belts starting with the overflow facies, well-seismic combination is performed on the planar facies of the volcanic rock to depict the planar facies belt of the volcanic rock in the study area.

[0038] The present disclosure has the following beneficial effects:

[0039] For the method for depicting a volcanic body of the present disclosure, firstly, by obtaining the seismic-geological profile characteristics corresponding to each geological stratification of the volcanic body and extracting the multi-channel coherent average energy slice of the volcanic body to depict the volcanic conduit facies, the volcanic vent and the volcanic conduit can be quickly identified, and at the same time, the spatial distribution characteristics of the volcanic vent and the volcanic conduit can be intuitively reflected;

[0040] Secondly, by performing multi-channel coherent reflection intensity slope slice processing on the geological stratification of the volcanic body and combining the seismic-geological profile characteristics to determine the main development positions of the volcanic body, the volcanic body profile characteristics with relatively small characteristic differences can be effectively identified, and the depiction of the volcanic body formed in different eruption periods can be completed;

[0041] Thirdly, according to the single-well facies division results of the volcanic body, combined with the multi-channel coherent reflection slope intensity slices, the distribution areas of the explosive facies and the overflow facies are respectively delineated within the proximal facies of the volcanic body, and sensitive attributes of volcanic rock facies are preferably selected for multi-attribute clustering analysis to complete the planar facies belt delineation of volcanic rocks, realizing the division of volcanic rock facies. This way of dividing volcanic rock facies is more conducive to showing the distribution law of the volcanic body on the plane and facilitating the prediction and summary of the distribution and development law of volcanic rock reservoirs. Brief Description of the Drawings

[0042] Through the description of the embodiments of the present disclosure with reference to the following drawings, the above and other objects, features, and advantages of the present disclosure will become clearer. In the drawings:

[0043] Figure 1 is a flowchart of the method for delineating a volcanic body based on multi-channel coherent reflection intensity slope attributes according to an embodiment of the present disclosure;

[0044] Figure 2 is a flowchart of the technical implementation of the volcanic body delineation according to an embodiment of the present disclosure

[0045] Figure 3 is a schematic diagram of the volcanic source identification result combining multi-channel coherent average energy slices and profiles according to an embodiment of the present disclosure;

[0046] Figure 4 is a schematic diagram of the distribution characteristics of the volcanic crater and the proximal volcanic crater facies according to an embodiment of the present disclosure;

[0047] Figure 5 is a schematic diagram showing that the volcanic crater and the proximal volcanic crater facies are located at the high position of the local structure according to an embodiment of the present disclosure;

[0048] Figure 6 is a schematic diagram of the volcanic eruption mode according to an embodiment of the present disclosure;

[0049] Figure 7 is a characteristic diagram of the volcanic eruption profile of the Yingcheng Formation according to an embodiment of the present disclosure;

[0050] Figure 8 is a schematic diagram of the distribution of volcanic bodies in the first member of the Yingcheng Formation according to an embodiment of the present disclosure. Detailed Embodiments

[0051] The following describes the present disclosure based on embodiments. However, it should be noted that the present disclosure is not limited to these embodiments. In the following detailed description of the present disclosure, some specific details are described in detail. However, for the parts that are not described in detail, those skilled in the art can also fully understand the present disclosure.

[0052] In addition, those of ordinary skill in the art should understand that the provided drawings are only for illustrating the purposes, features, and advantages of the present disclosure, and the drawings are not actually drawn to scale. At the same time, unless the context clearly requires otherwise, the words such as "including", "comprising", and the like in the entire specification and claims should be construed as having an inclusive meaning rather than an exclusive or exhaustive meaning; that is, it means "including but not limited to".

[0053] To make the objectives, technical solutions, and advantages of the present invention clearer and more understandable, the following further elaborates on the present invention in detail according to the drawings and by way of examples.

[0054] Referring to Figure 1 as shown, Figure 1 there is shown a method for depicting volcanic bodies based on the multi-channel coherent reflection intensity slope attribute, and the method includes the following steps:

[0055] S1: Based on the lithologic combination characteristics of volcanic rocks and according to the electrical cycle characteristics, construct an isochronous stratigraphic correlation framework for stratigraphic division of volcanic bodies to determine the geological stratification of volcanic bodies;

[0056] S2: Conduct well-seismic stratigraphic adjustment on the geological stratification, and perform horizon calibration on the adjusted seismic stratification to determine the seismic-geological profile characteristics corresponding to each geological stratification of the volcanic body;

[0057] S3: Based on the seismic-geological profile characteristics, extract multi-channel coherent average energy slices of the volcanic body and depict the volcanic conduit facies to determine the development range of the volcanic conduit facies;

[0058] S4: Perform multi-channel coherent reflection intensity slope slice processing on the geological stratification of the volcanic body, and combine the seismic-geological profile characteristics to determine the main development positions of the volcanic body;

[0059] S5: According to the development range of the volcanic conduit facies and the main development positions of the volcanic body, combine the effective reservoir prediction results of the geological stratification to conduct near-source facies depiction to determine the development range of volcanic facies belts;

[0060] S6: According to the single-well facies division results of the volcanic body, combine the multi-channel coherent reflection slope intensity slices, depict the distribution areas of explosive facies and overflow facies within the near-source facies, and preferably select sensitive attributes of volcanic rock facies for multi-attribute clustering analysis to depict the planar facies belts of volcanic rocks.

[0061] Furthermore, in one implementation, the step of based on the lithologic combination characteristics of volcanic rocks and according to the electrical cycle characteristics, construct an isochronous stratigraphic correlation framework for stratigraphic division of volcanic bodies to determine the geological stratification of volcanic bodies; specifically includes:

[0062] Using the existing well logging, logging while drilling (LWD) data and 3D seismic data of volcanic rocks, based on the lithologic combination characteristics of regional standard wells, and taking the electrical cycle characteristics as the basis, the stratigraphic characteristics of volcanic bodies are compared by the combined logging curve characteristic comparison method, the gas reservoir groups in the volcanic bodies are divided, and an isochronous stratigraphic correlation framework integrating wells and seismic data for the whole region is constructed according to the comparison and division results to determine the geological stratification of the volcanic bodies.

[0063] In the specific practical process, the production environments of the strata in the volcanic body study area vary greatly in different geological periods, resulting in obvious differences in lithology, lithofacies and even rock types in different formations and sections. According to the characteristics of rock combinations, contact relationships, curve characteristics and seismic reflection characteristics, the strata in the volcanic body study area can be divided into the Shahezi Formation, the Yingcheng Formation and the Denglouku Formation from bottom to top. The lithologic, electrical and seismic characteristics of each formation and section and their interfaces are shown in Table 1 below:

[0064] Table 1 Lithologic, Electrical and Seismic Characteristics of Major Stratigraphic Interfaces

[0065]

[0066] Based on the analysis of the lithologic, electrical and seismic characteristics of each formation and section and their interfaces in Table 1 above:

[0067] 1. Lithologic, Electrical and Seismic Characteristics of the Yingcheng Formation

[0068] During the sedimentation period of the Yingcheng Formation, the basement faults were activated and tectonic movements were frequent, resulting in intense volcanic activities. In the fault depression, extensive volcanic rocks were formed over a large area. The volcanic rocks in the Yingcheng Formation are mainly acidic and intermediate-acidic rocks, and there are also intermediate-basic volcanic rocks. A set of sedimentary rock interlayers with a small thickness are developed in some areas. The main rock types include agglomerate, tuff, welded breccia, welded tuff, volcanic breccia, rhyolite, dacite, andesite, basalt, etc. The electrical characteristics are as follows: the natural gamma ray shows a medium-amplitude box shape, the deep and shallow lateral resistivity shows a high-amplitude box shape, the neutron density is high, and the acoustic time difference is low, etc.

[0069] According to the situation of the strata drilled by exploration wells in the study area, the strata of the Yingcheng Formation can be divided into Ying 1 Member and Ying 4 Member.

[0070] 1) Strata of Ying 1 Member of the Yingcheng Formation:

[0071] It is mainly composed of acidic volcanic rocks, and intermediate-basic volcanic rocks can be seen at the lower part. The common rock types include rhyolite, tuff, volcanic breccia, welded breccia, welded tuff, andesite, basalt. From the drilling exposure situation, it is mainly composed of volcanic clastic lava, volcanic clastic rocks and acidic lava. The strata of Ying 1 Member of the Yingcheng Formation overlie the Xudong fault plane in the east.

[0072] 2) Strata of Ying 4 Member of the Yingcheng Formation:

[0073] The whole overlaps the Ying 1st stratum and contacts the underlying stratum in an unconformable relationship, with a clear interface and obvious characteristics. The Ying 4th stratum can be divided into two sections, the upper section is characterized by sandstone and conglomerate, and the lower section is characterized by interbedded sandstone and mudstone.

[0074] 3) Top interface of Yingcheng Formation (T4):

[0075] Lithology: The interface between the interbedded sandstone and mudstone of the fourth member of the Ying Formation;

[0076] Electrical properties: The upper part of the logging curve is jagged and the lower part is straight, with the resistivity lower at the top and higher at the bottom;

[0077] Earthquake: Regional unconformity surface, with obvious truncation characteristics below and obvious top-overlap characteristics above. The T4 reflection layer is a regional strong reflection interface.

[0078] 4) The bottom interface of the camp group:

[0079] It is the interface where the lacustrine sandstone of the Shahezi Formation suddenly changes into the volcanic rock or conglomerate of the Yingcheng Formation. The characteristics are obvious. On the seismic section, this interface has obvious truncation and onlap characteristics.

[0080] 2. Lithological, electrical and seismic characteristics of the Denglouku Formation

[0081] The Denglouku Formation is mainly a set of fluvial-deltaic sandstone-mudstone interbedded rocks of unequal thickness. It is divided into three sections according to the sedimentary rhythm (the first section of the Denglouku Formation is missing), and each section is an anticycle that coarsens upward.

[0082] The rock types of the dark mudstone section of the second section of the Denglouku Formation are mainly gray, gray-black, green-gray, brown-gray mudstone and gray, gray-white fine sandstone, siltstone interbedded with varying thicknesses, with a small amount of brown mudstone. In general, mudstone accounts for more than 50% of the thickness of this section, and thick conglomerate or sandy conglomerate is often developed at its bottom near the source area.

[0083] The rock types of the third section of the massive sandstone of the Denglouku Formation are mainly gray-white and gray-green massive sandstone intercalated with gray-green, brown-gray and gray-brown sandy mudstone. Mud gravel is common at the bottom, generally in a positive rhythm of coarse at the bottom and fine at the top.

[0084] The transitional lithology section of the fourth section of the Denglouku Formation is interbedded with gray-brown mudstone and gray-white fine sandstone of varying thickness. The mudstone is pure, the sandstone is medium-thick and massive, and gravel is seen at the bottom, mostly with positive rhythm. The third section of the Denglouku Formation is richer in sandy debris than the second and fourth sections of the Denglouku Formation, and the sediment grain size is also relatively coarse. The bottom interface of the Denglouku Formation in the region is the interface where the volcanic rock or conglomerate of the Yingcheng Formation suddenly changes to the clastic sedimentary rock of the Denglouku Formation. On the seismic profile, it has obvious top-lap and onlap characteristics.

[0085] 1) Denglouku gas layer

[0086] Stratum: The Denglouku Formation is developed in 3 segments (the first segment of Denglouku Formation is missing), and 5 gas reservoir groups are developed in the third and fourth segments of the Denglouku Formation.

[0087] Lithology: Sandstones are developed in the third segment of Denglouku Formation, while mudstones are mainly developed in the fourth and second segments of Denglouku Formation.

[0088] Electrical property: The gamma and resistivity step features at the boundaries of each segment are relatively obvious, and each gas reservoir group is divided based on sedimentary cycle features.

[0089] Seismic: For the 5 gas reservoir groups developed in the third and fourth segments of Denglouku Formation, the top surfaces of each gas reservoir group are parallel and continuously medium-weak reflections. The results of fine horizon calibration show that the 5 gas reservoir groups, from top to bottom, respectively correspond to "peak, valley, peak, valley, peak, valley" of the seismic profile.

[0090] 2) Top interface of the Denglouku Formation (T3)

[0091] Lithology: The interface between the underlying mudstone of the fourth segment of Denglouku Formation and the bottom sandstone of the first segment of Quan Formation.

[0092] Electrical property: The step features of DT and GR curves are relatively clear.

[0093] Seismic: It is a set of relatively continuous reflections with medium-weak amplitude, and unconformity features can be seen locally.

[0094] The geological stratification of volcanic rocks is a process of establishing the isochronous corresponding relationship between well layer groups within the study area based on elements such as the contact relationship of strata, volcanic eruption cycles, and periodic relationships. Reasonable stratigraphic division is the basis for structural interpretation and reservoir prediction.

[0095] This application makes full use of the logging and well logging data of existing wells and 3D seismic data in the volcanic body study area. Based on the lithological combination characteristics and relying on the electrical cycle characteristics, the volcanic rock strata of the first segment of Ying Formation in the study area are redefined, an isochronous stratigraphic correlation framework consistent throughout the area is established, and the stratigraphic division process is determined. The joint multi-stratigraphic stratification of drilling - well logging - seismic is carried out in the whole area. Through the macroscopic consistency comparison of well and seismic data, the stratigraphic characteristics of each group and segment are clarified, and the drilling stratification is adjusted to ensure the accuracy of drilling geological stratification and the reliability of seismic interpretation horizons.

[0096] Among them, the methods involved in the volcanic rock stratigraphic correlation process mainly include volcanic rock lithology correlation method, volcanic rock cycle correlation method, and combined well logging curve feature correlation method.

[0097] The volcanic rock lithology correlation method mainly correlates the lithology of volcanic rocks. Lithology correlation is a commonly used correlation method in a small area. Its basis is the volcanic eruption principle and the similarity of lithology in adjacent areas, the sequentiality and continuity of lithology changes during the accumulation of eruption materials. Lithology stratification is carried out by using the characteristics of rock color, composition, lithology, structure, texture and cyclicity, etc., and then the inter-well formation correlation is carried out. The change of lithology will inevitably lead to the difference of logging curves. Therefore, the lithology can be indirectly correlated by using logging curves. Logging curve correlation is carried out according to the similarity of curves of adjacent wells in the same layer, or controlled by several stable electrical marker beds, and considering lithofacies changes. The superiority of using logging curves for formation correlation lies in that it provides continuous records of the whole well sections of all wellbores. More importantly, its depth is relatively accurate and it can reflect the properties of rocks from different aspects.

[0098] The basis of the volcanic rock cycle correlation method is that volcanic eruptions often show regular periodic changes in lithology, composition and eruption intensity. This kind of change is called eruption cycle, which is often associated with specific tectonic movements. According to the cycle change law in a certain area, cycle correlation can be carried out.

[0099] During a certain geological history period, the volcanic eruption materials caused by specific tectonic movements are similar, and the combined logging curve characteristics should also have a certain similarity. In the absence of marker beds, this similarity can be used as the basis for the correlation of adjacent well formations.

[0100] The combined logging curve characteristic correlation method is divided into single curve characteristic correlation and multi-curve characteristic correlation. Single curve characteristic correlation is to use the longitudinal sequence characteristics of a single curve and carry out correlation between different well points through graphic pattern recognition. Multi-curve correlation is to use the combined characteristics of the depth sequences composed of multiple curves for correlation. When the single curve characteristics are not obvious and the correlation markers cannot be determined, multiple characteristics of multiple curves can be jointly judged. Therefore, this application adopts the combined logging curve characteristic correlation method for formation correlation, and then constructs an isochronous formation correlation framework. The specific steps of this process are as follows:

[0101] ①Based on the preliminary division of single-well formations, guided by the above-mentioned method principles, 11 well-seismic framework profiles were established, passing through 40 wells. Comparison was carried out in the order of "point - line - surface" to achieve closure in the whole area; ②Stratigraphic groups were compared using standard horizons and eruption cycles; ③Comparison lines were connected for multi-well closure; ④During the comparison process, geological analysis and dynamic verification were carried out. By analyzing the origin and structural characteristics of each layer, characteristic anomalies occurring in the comparison were eliminated from the perspectives of volcanic lithofacies and lithology; ⑤The results of comparison and division were repeatedly calibrated and modified on the seismic profile to achieve consistency between wells and seismic data; ⑥After repeated analysis and deliberation, the well-seismic stratigraphic comparison framework for the whole area was finally determined, the data table of eruption periods for each well in the work area was compiled, and the division of the top and bottom surfaces of the first member of the Yingcheng Formation and the gas-bearing formation groups was completed. Finally, in close combination with seismic reflection characteristic information, multi-well arbitrary-line closure detection was carried out for mutual verification, ensuring the consistency of inter-well horizon division and comparison and the interpretation results of fault point positions and seismic phases for each well in the work area, and ensuring the reliability of stratigraphic comparison results and the unity of the region.

[0102] Further, in one implementation, the well-seismic stratigraphic adjustment is performed on the geological stratification, and the horizons of the adjusted seismic stratification are calibrated to determine the seismic-geological profile characteristics corresponding to each geological stratification of the volcanic body; specifically including:

[0103] Based on the well-seismic combined cross-well profiles, the stratification depths between each geological stratification of the volcanic body are adjusted to unify the stratification standards among wells;

[0104] Based on the seismic-geological profile of the volcanic body and the drilling stratification results, using well logging information as a bridge, synthetic seismogram calibration is performed on the target wells in the adjusted geological stratification of the volcanic body to obtain the seismic reflection wave group characteristics corresponding to each geological interface, and the seismic-geological profile characteristics corresponding to each geological stratification of the volcanic body are determined.

[0105] In one embodiment, there are 40 wells in the volcanic body research area of this application, and the target stratigraphic intervals studied in this application are the Yingcheng Formation and the Denglouku Formation. The stratigraphic division and comparison in this application are based on the existing stratigraphic division results, taking the lithologic combination characteristics of regional standard wells as the basis and the electrical cycle as the foundation. Key through the combination of wells and seismic data, each major layer is defined, and at the same time, the gas-bearing formation groups are divided. Through the combination of wells and seismic data, 11 well-seismic comparison framework profiles are made through 40 wells in the whole area. After repeated adjustment, finally, the unity between wells and seismic data and the closure of the whole area are achieved.

[0106] This time, the Yingcheng Formation is divided into the fourth member of the Yingcheng Formation (Yc4) and the first member of the Yingcheng Formation (Yc1). The fourth member of the Yingcheng Formation is divided into two gas-bearing formation groups, namely Yc4Ⅰ and Yc4Ⅱ. The first member of the Yingcheng Formation is divided into two gas-bearing formation groups and three sub-layers, namely Yc1Ⅰ1, Yc1Ⅰ2, and Yc1Ⅰjc (see Table 2 below).

[0107] The Denglouku Formation is divided into 3 segments. Among them, the second member of the Denglouku Formation is divided into 2 gas reservoir groups, the third member is divided into 3 gas reservoir groups, and the fourth member is divided into 2 gas reservoir groups (see Table 3 below).

[0108] Table 2 Stratification Scheme of the Denglouku Formation

[0109]

[0110] Table 3 Stratification Scheme of the Yingcheng Formation

[0111]

[0112] The object of the well-seismic integrated stratification adjustment in this application is the stratification depth of the Yingcheng Formation and the Denglouku Formation. The specific changes in the stratigraphic horizons after the stratification adjustment are as follows:

[0113] 1) Stratification of the Denglouku Formation

[0114] Based on the above stratigraphic division and correlation scheme and the clastic rock stratigraphic division and correlation method, on the basis of the analysis of the lithological, electrical, and seismic characteristics, and according to the well-seismic integrated cross-well profile, through the seismic 1*1 CDP interpretation, the stratigraphic group division adjustment of the Denglouku Formation has been completed. A total of 11 wells and 28 stratifications in the Denglouku Formation have been adjusted (see Table 4 below). After the adjustment, the stratification criteria among wells are unified, the seismic response characteristics are relatively consistent, and the well-seismic consistency has improved significantly.

[0115] Table 4 Modified Stratification Data Table of the Denglouku Formation

[0116]

[0117] 2) Stratification adjustment of the Yingcheng Formation

[0118] A total of 16 wells and 26 well-point stratifications in the Yingcheng Formation have been adjusted (the adjusted stratification data are shown in Table 5 below).

[0119] Table 5 Modified Stratification Data Table of the Yingcheng Formation

[0120]

[0121] Before the stratification adjustment, there was still volcanic rock above the upper part of Yc1Ⅰ1. In order to unify it with the whole area, it was adjusted to the top of the volcanic rock. 19 wells and 26 stratification data have been added to the Yingcheng Formation (the newly added stratification data are shown in Table 6 below).

[0122] Table 6 Newly Added Stratification Data Table of the Yingcheng Formation

[0123] Well Name Layer Name Layer Depth (m) Well Name Layer Name Layer Depth (m) C103 JC 3371.18 FS6-2 YC12 3509.44 FS10 YC12 3493.03 FS6-2 JC 3549.4 FS10 JC 3502 FS6-P1DY JC 3513 FS101 YC12 3534.88 FS7 JC 3506 FS101 JC 3584.17 FS701 JC 3603.4 FS11 JC 3755.3 FS8 YC12 3568 FS12HC JC 3685.19 FS9 YC12 3646.4 FS12HCDY YC12 3637 FS9-1 YC12 3684.8 FS12HCDY JC 3649.9 FS9-3 YC12 3618.6 FS6 YC12 3350.05 FS9-3 JC 3633 FS6 JC 3409.9 SS5 YC12 3546.977 FS6-1 YC12 3495 XS33 JC 3815 FS6-1 JC 3509 XS606 JC 3911.3

[0124] Among them, layer calibration is the bridge connecting seismic, logging, and geology, and is the key to structural interpretation. The accuracy of layer calibration is directly related to the success or failure of reservoir prediction. Only with accurate calibration can it be possible to use seismic data to more accurately describe the geometric morphology and other relevant parameters of the reservoir. There are many methods for layer calibration, such as average velocity, VSP, synthetic records, etc. The layer calibration of this application is based on the drilling stratification results, with logging information as a bridge, based on seismic geological profiles, and an artificial synthetic record calibration method through all-round well profile dragnet comparison.

[0125] Specifically, the basic principles of layer calibration in this application are as follows:

[0126] (1) Using the one-to-one correspondence between the breakpoints on the seismic profile near the well and the breakpoints of the well geological stratification, the accuracy of the velocity used is verified and corrected;

[0127] (2) When making synthetic seismic records, environmental correction is performed on the acoustic logging curve to eliminate the influence of well diameter changes;

[0128] (3) Wells with density logging data must be used when making synthetic seismic records;

[0129] (4) Multi-well calibration: In areas where the reflection characteristics of the target layer have a large phase change, multiple representative wells in different fault blocks are selected for calibration, which can help understand the changes in the wave group characteristics of each fault block;

[0130] (5) Selection of standard wells: select wells with complete formations, few faults, relatively gentle occurrence, clear characteristics of seismic data near the well, and acoustic time difference curves that are less affected by factors such as well wall collapse and mud soaking as standard wells;

[0131] (6) Wavelet selection. When making synthetic records, we used bandpass wavelets, Ricker wavelets, and wavelets extracted from well bypass seismic data to make synthetic records, and compared them;

[0132] (7) The principles for selecting wells for producing synthetic seismic records in this area are: first, the quality of seismic records near the wells is reliable, they should not cross faults as much as possible, and the wells should be located in the middle of the fault block as much as possible; second, the logging data is reliable and the logging section is long; third, they are distributed in different phase belts and are representative of the block.

[0133] Furthermore, when using the same well logging acoustic wave curve to produce synthetic seismograms with different wavelets, synthetic seismograms with different matching effects with the actual section will be obtained. Therefore, we conducted experiments with different wavelets, and successively produced synthetic seismograms using the Ricker wavelet, the minimum-phase wavelet extracted from the actual seismic trace beside the well, and the zero-phase wavelet. Through spectral analysis, it can be known that the main frequency of the seismic data in the Denglouku Formation is 30 Hz, and the main frequency of the seismic data in the Yingcheng Formation is 25 Hz. Therefore, first synthesize the theoretical Ricker wavelet that matches its frequency bandwidth; use these theoretical wavelets and the well logging impedance curve to generate synthetic seismic records, align the main wave groups of the two, select an appropriate time window (containing the target interval, and try to select the starting time in the time period with weak or no seismic reflection), extract the seismic wavelet, and use the newly extracted wavelet to generate a new synthetic seismic record; adjust the time-depth relationship curve to make the synthetic seismic record gradually approach the actual seismic trace; repeat the above steps until the obtained synthetic record and the seismic record reach the best match. The wavelet obtained by this method has the same frequency band as the actual record, and has a good corresponding relationship with the wave group relationship of the actual seismic record. After calibration, it is considered that this 3D seismic data is a positive polarity section.

[0134] The present application has completed the fine calibration of synthetic seismograms for 40 wells according to the above layer calibration process and calibration principles. At the same time, based on the fine calibration of each major layer, well-seismic fine bridge calibration has been carried out for 12 gas reservoir groups in the Denglouku Formation and the Yingcheng Formation. Through bridge calibration, the lithological, electrical, and seismic correlation relationships of the gas reservoir groups have been clarified.

[0135] Furthermore, in order to further verify the accuracy of calibration, based on the single-well synthetic seismogram calibration, the present application connected the wells that have made synthetic seismograms in the 3D data volume to check whether all wells are calibrated to the same layer. If there are wells that do not match the layer, the velocity curve needs to be analyzed and recalibrated, and the synthetic seismogram needs to be remade until it matches. Finally, the layers calibrated by the synthetic seismogram are traced to the same plane in the 3D data volume. Through the bridge calibration of 40 wells in the whole area, the seismic reflection wave group characteristics corresponding to each geological interface, that is, the seismic-geological section characteristics, have been determined, laying a solid foundation for the fine structural interpretation of volcanic body geological stratification in the next step.

[0136] By comparing the velocity extracted from the synthetic seismogram of a single well with the comprehensive velocity in the Changde area of the northern Songliao Basin, the velocities of the two are basically the same. The maximum deviation is only 5 - 8 ms, which indicates that the velocity in the Changde area is stable and the lateral variation is small. Therefore, the calibration of all wells is slightly adjusted based on the comprehensive velocity calibration.

[0137] Furthermore, in one implementation, based on the seismic-geological section characteristics, multi-channel coherent average energy slices of the volcanic body are extracted to depict the volcanic conduit facies, and the development range of the volcanic conduit facies is determined; specifically including:

[0138] Based on the characteristics of seismic geological profiles, the geological stratification of the volcanic body is interpreted by the volcanic crater profile interpretation technology, the volcanic crater profile is identified, the profile characteristics of the volcanic conduit are extracted from the seismic geological profile, and the location of the volcanic crater is determined;

[0139] The coherent data volume of the geological stratification of the volcanic body is obtained, and multi-trace coherent average energy slices are extracted from the coherent data volume for plane fault interpretation, the volcanic crater and the volcanic conduit plane are identified, and the plane distribution characteristics of the volcanic crater and the volcanic conduit are obtained;

[0140] Based on the plane distribution characteristics of the volcanic crater and the volcanic conduit, the profile characteristics of the volcanic conduit, and the location of the volcanic crater, three-dimensional visualization interpretation of the geological stratification of the volcanic body is carried out, the spatial distribution characteristics of the volcanic crater and the volcanic conduit are obtained, and the development range of the volcanic conduit facies in the geological stratification is determined according to the spatial distribution characteristics of the volcanic crater and the volcanic conduit.

[0141] Further, in one embodiment, multi-trace coherent reflection intensity slope slice processing is performed on the geological stratification of the volcanic body, and the main development location of the volcanic body is determined in combination with the characteristics of the seismic geological profile; specifically including:

[0142] Based on the characteristic data of the volcanic rock mass encountered in the known well, the horizon calibration of the volcanic rock mass is carried out on the seismic geological profile;

[0143] Based on the horizon calibration result of the volcanic rock mass, volcanic body profile interpretation is carried out, and the volcanic body profile is identified according to the reflection characteristic differences of the post-stack seismic profile, the three-instant profile and the pure wave profile, and the volcanic body profile characteristics are obtained;

[0144] On the basis of the identification of the volcanic body profile, extrapolation interpretation of the volcanic body plane is carried out, the volcanic body plane is identified, and the volcanic body plane characteristics are obtained;

[0145] Multi-trace coherent reflection intensity slope slice processing is performed on the coherent data volume of the geological stratification of the volcanic body, multi-trace coherent reflection intensity slope slices of the volcanic body are extracted, and multi-trace coherent reflection intensity slope attributes of the volcanic body are obtained;

[0146] Combined with the volcanic body profile characteristics and the volcanic body plane characteristics, volcanic body identification is carried out on the seismic geological profile, and referring to the multi-trace coherent reflection intensity slope attributes, combined with the profile seismic reflection characteristics, the main development location of the volcanic body is comprehensively determined.

[0147] Further, in one embodiment, based on the development range of the volcanic conduit facies and the main development location of the volcanic body, near-source facies characterization is carried out in combination with the effective reservoir prediction results of the geological stratification, and the development range of the volcanic facies belt is determined; specifically including:

[0148] Effective reservoir prediction is carried out on the geological stratification of the volcanic body to obtain effective reservoir prediction results;

[0149] Combined with the development range of the volcanic conduit facies, the main development positions of the volcanic bodies, and the effective reservoir prediction results, the proximal facies are characterized, and the volcanic bodies are divided into the crater - near - crater facies, proximal facies, and distal facies to determine the development range of the volcanic facies belts.

[0150] Furthermore, in one embodiment, based on the single - well facies division results of the volcanic bodies, combined with the multi - trace coherent reflection slope intensity slices, the distribution areas of the explosive facies and effusive facies are delineated within the proximal facies, and sensitive attributes of volcanic rock facies are preferably used for multi - attribute clustering analysis to delineate the planar facies belts of volcanic rocks; specifically including:

[0151] Based on the single - well facies division results of the volcanic bodies, combined with the multi - trace coherent reflection slope intensity slices, the distribution areas of the explosive facies and effusive facies are delineated within the proximal facies;

[0152] Using the attribute waveform clustering method, the planar facies of volcanic rocks corresponding to each target layer and the single - well facies of the volcanic bodies are divided in the geological stratification, and the planar Seino waveform clustering parameters are optimized and clustering attributes are extracted based on the divided planar facies of volcanic rocks. Using the planar sensitive attributes of Seino waveform clustering, combined with the single - well gas - testing productivity of the volcanic bodies, the facies belts starting with the explosive facies and the facies belts starting with the effusive facies are delineated within the distribution areas of the explosive facies and effusive facies;

[0153] Based on the delineated facies belts starting with the explosive facies and the facies belts starting with the effusive facies, well - seismic combination is carried out for the planar facies of volcanic rocks to delineate the planar facies belts of volcanic rocks.

[0154] In order to improve the accuracy of fault interpretation, in view of the characteristics of seismic data of clastic rock and volcanic rock strata, the "multi - set data volume joint interpretation technology" is adopted in the structural interpretation process of geological stratification in this application. The faults and volcanic bodies are interpreted in detail from different angles of plane, profile, and space, and special attention is paid to the interpretation and discovery of small faults.

[0155] Among them, the plane fault interpretation technology: includes seismic data volume time slice interpretation technology, coherence volume time slice interpretation technology, and fault dip analysis technology. Using these technologies, the closure of the fault plane in three - dimensional space can be carried out quickly and simply, and the planar distribution characteristics of the faults can be reflected quickly and accurately, making smaller faults show more clearly.

[0156] The profile fault interpretation technology: refers to the parallel multi - line joint interpretation technology, arbitrary line joint interpretation technology, and profile longitudinal magnification and reduction interpretation technology. Using this technology, the positions of faults in the profile and plane can be determined.

[0157] The above technical method plays an important role in the interpretation of volcanic structures, observing and identifying faults, fault termination points, fault contact relationships, determining fault positions for breakpoint combination, and reducing the ambiguity of fault interpretation, making the fault interpretation more reasonable.

[0158] Spatial volcanic structure interpretation technology: refers to the three-dimensional visualization interpretation technology of volcanic structures. Using this technology for volcanic structure interpretation can intuitively reflect the spatial distribution characteristics of volcanic structures and can intuitively check and verify the rationality of volcanic structure interpretation. It is a useful tool for testing the basic skills of interpreters.

[0159] Refer to Figure 2 As shown, on the basis of obtaining the characteristics of seismic geological profiles, this application mainly uses the above-mentioned multi-data volume joint interpretation technology and then mainly completes the identification of volcanic conduits, the identification of volcanic bodies, and the division of volcanic facies (volcanic rock facies).

[0160] Among them, before the identification of volcanic conduits, it is necessary to identify volcanic rocks and analyze the structural characteristics, slice characteristics, profile characteristics, distribution characteristics, etc. of volcanic rocks. The specific process is as follows:

[0161] 1) Seismic reflection structural characteristics of volcanic rocks

[0162] Using seismic profile characteristics to identify volcanic rocks is one of the most intuitive methods. Volcanic rocks mainly have the following identification marks on seismic profiles.

[0163] The volcanic rocks in the first member of the Yingcheng Formation in the Changde area mostly show mound-shaped reflections, and the top surface reflection strength is affected by the surrounding rock; the internal reflection characteristics are strong amplitude, low frequency, and the isophase axis is discontinuously distributed, with strong energy, and has low-angle oblique, parallel, and blank chaotic reflection structures. The overlying sedimentary rocks show low-frequency, strong-amplitude, and relatively continuous reflections. The underlying sedimentary rocks show high-frequency, medium-amplitude, and parallel reflections.

[0164] 2) Differences between volcanic rocks and sedimentary rocks

[0165] The reflection difference between volcanic rock bodies and sedimentary rocks is that volcanic rocks show mound-shaped and low-frequency reflections. The reflections of volcanic rock bodies mostly show strong amplitude, low frequency, discontinuous mound shape, and low-angle oblique structures. Sedimentary rocks have a layered structure appearance, and the isophase axis is relatively continuous and stable compared with volcanic rocks.

[0166] 3) Time slice characteristics of volcanic rocks

[0167] Seismic slices can reflect the changes in the amplitude, frequency, and continuity of each seismic event within a certain time-depth range, and are relatively effective in identifying volcanic rocks. Generally, within the range of volcanic rocks, the frequency of seismic events is relatively low, the continuity is poor, and there are obvious boundaries with the surrounding strata. By browsing slices at different times, the boundaries of volcanic rocks at different times can be accurately delineated, thereby interpreting the spatial distribution of volcanic rocks three-dimensionally. Therefore, time slices can be used to identify the macroscopic distribution of volcanic rock bodies.

[0168] 4) Characteristics of the seismic three-instantaneous profiles of volcanic rocks

[0169] Volcanic rocks mainly exhibit three types of anomalies when analyzed from seismic three-instantaneous profiles: First, phase anomaly. Volcanic rocks have the characteristics of instantaneous phase anomaly. On the instantaneous phase profile, it is manifested as strong phase oblique reflection, which is significantly different from the instantaneous phase of sedimentary rocks and surrounding rocks. Second, frequency anomaly. Volcanic rocks have the characteristics of low instantaneous frequency anomaly. On the instantaneous frequency profile, it is manifested as low-frequency reflection, which is significantly different from the instantaneous frequency of sedimentary rocks and surrounding rocks. It can be seen that there is a phenomenon of low-frequency anomaly within the range of volcanic rocks. Third, amplitude anomaly. Volcanic rocks have the characteristics of strong amplitude, and this strong amplitude reflection characteristic is very clear on the instantaneous amplitude profile. The three-instantaneous profile is a relatively effective method for identifying volcanic rocks in the study area.

[0170] 5) Distribution characteristics of the volcanic rocks in the Yingcheng Formation

[0171] In the Changde area, the first member of the Yingcheng Formation is mainly composed of volcanic rocks. From the early stage to the late stage of the first member of the Yingcheng Formation, a volcanic eruption cycle developed, corresponding to the Yc1Ⅰ gas reservoir group. The Yc1Ⅰ gas reservoir group is further divided into two small layers, Yc1Ⅰ1 and Yc1Ⅰ2. Sandstone and mudstone interlayers are developed at the lower part of the Ⅰ gas reservoir group. The fourth member of the Yingcheng Formation is mainly composed of clastic rocks. The lithological combination characteristics are as follows: The grain size is fine in the upper and lower parts, mainly developing sandstone and mudstone, mainly mudstone intercalated with sandstone, and less developing conglomerate; the grain size is coarse in the middle part, mainly developing conglomerate and coarse sandstone. In summary, the volcanic rocks in the first member of the Yingcheng Formation are widely developed vertically and horizontally.

[0172] After identifying the volcanic rocks, the volcanic crater and volcanic conduit are identified by combining plane and profile analysis. The specific process is as follows:

[0173] A volcanic edifice refers to the rock-tectonic bodies related to volcanic activities, such as volcanic conduits, volcanic craters, volcanic cones, radial and circular dike swarms, etc. The volcanic conduit is the channel for magma to upwell from underground and is an important part defining the volcanic edifice.

[0174] 1) Plane identification

[0175] The planar identification of volcanic craters and volcanic channels includes seismic data volume time slice interpretation techniques and multi-channel coherent average energy slice interpretation techniques. Using these techniques, the identification of volcanic craters in three-dimensional space can be carried out quickly and simply, and the planar distribution characteristics of volcanic craters and volcanic channels can be reflected quickly and accurately, making smaller volcanic craters more clearly displayed.

[0176] The powerful force of volcanic eruptions causes strong damage to the strata near the volcanic crater, forming numerous fractures, micro-fractures and cracks. Coherent body slices can identify them well, but the scale of the volcano in the study area is relatively small, and the identification of conventional coherent body slices is not very obvious. Therefore, we extracted average energy slices and reflection intensity slope slices respectively on the basis of coherent bodies to determine the distribution position of the volcanic crater and the scope of the near-source volcanic body. The volcanic source identification result map is as Figure 3 shown.

[0177] 2) Profile identification

[0178] The volcanic crater profile interpretation techniques include parallel multi-line joint interpretation techniques, arbitrary line joint interpretation techniques, profile longitudinal zoom interpretation techniques and auxiliary interpretation techniques using instantaneous amplitude, instantaneous phase and instantaneous frequency profiles. Using this technique, the position of the volcanic crater on the profile can be determined.

[0179] The volcanic channel has the following characteristics on the profile:

[0180] a The external seismic reflection shape is conical, and the top interface is generally a strong amplitude;

[0181] b The internal seismic reflection structure is high-angle oblique reflection, and the dip angle of the rock formation gradually decreases from near to far from the volcanic crater;

[0182] c The internal seismic reflection structure is chaotic or blank;

[0183] d There is often an overlying structure above the volcanic rock mass, and there is an onlap phenomenon in the surrounding rock strata on both wings.

[0184] 3) Spatial identification

[0185] The spatial identification of volcanic craters and volcanic channels refers to the identification using three-dimensional visualization interpretation techniques. Using this technique for volcanic crater interpretation can intuitively reflect the spatial distribution characteristics of volcanic craters and volcanic channels, and can intuitively check and verify the rationality of volcanic crater interpretation. It is a useful tool for testing the basic skills of interpreters.

[0186] Using the above methods plays an important role in observing and identifying volcanic craters, determining the positions of volcanic craters, and reducing the multi-solution nature of volcanic crater interpretation, making the volcanic crater interpretation more reasonable.

[0187] The volcanic channels below the crater show chaotic reflections, with attitudes significantly different from those of the surrounding rocks. They are longitudinally banded and communicate with deep major faults, and annular in plan view.

[0188] 4) Distribution characteristics of the crater and near-crater facies

[0189] Based on the planar, sectional, and spatial characteristics of the craters identified by seismic data, the distribution of the craters was recognized. The crater and near-crater facies in the study area are relatively developed and are distributed in a strip along the Xuxi Fault. In addition, the strata near the crater are developed, and the thickness rapidly thins away from the crater. Therefore, in general, the location of the crater can be analyzed based on the thickness of the volcanic rocks. The crater and near-crater facies of each small layer in the first member of the Yingcheng Formation show thickening of the strata in a strip along the Xuxi Fault, so the craters are also concentrated in these strips. The crater and near-crater facies of each small layer are located at the high positions of local structures. The distribution characteristics of the craters and near-crater facies are referred to Figure 4 , and the crater and near-crater facies are located at the high positions of local structures, referred to Figure 5 .

[0190] By identifying the craters through planar and sectional views, it is considered that the craters in the first member of the Yingcheng Formation in the Changde area have the following characteristics:

[0191] a On the section, it has an up-convex reflection configuration, and in the plane, it has an annular reflection feature. Due to the differential compaction in the later stage at the upper part of the volcanic cone, some may form grabens or have a concave-down reflection configuration, which is an important feature for identifying craters using seismic sections.

[0192] b The reflection of the magma channel is unclear. Due to the impregnation of magma, the bedrock at the lower part of the volcanic rock shows chaotic reflections, resulting in unclear reflection of the volcanic channel.

[0193] c The magma channel is mainly composed of fractures. The magma first surges along the fault and then intrudes into the bedrock. After impregnation and differentiation in the bedrock, it extrudes to the surface for eruption, forming the crater.

[0194] d The crater is associated with the basement fault. The basement fault induces the upwelling and eruption of magma, and the crater is associated with the basement fault; the distribution of the crater is generally consistent with the extension direction of the basement fault zone.

[0195] According to the above characteristics, combined with the wells that have drilled through the volcanic channel facies, a comprehensive analysis is carried out for volcanic channel identification. The final seismic identification results are consistent with the known wells.

[0196] After completing the identification of the volcanic channel, it is necessary to analyze the volcanic eruption mode, and the specific process is as follows:

[0197] 1) Formation mechanisms of different eruption modes

[0198] During the a fracture activity period, fracture fissures developed on the fault surface, magma welled up, and erupted on the surface. The development scale of the eruptive rock is determined by the development degree of the fracture fissures. When the tectonic movement is intense and the fault fissures are well developed, the development scale of the eruptive rock is relatively large; otherwise, it is relatively small.

[0199] The b basement major fault is the magma upwelling channel. Magma ejects onto the surface along the fissures, and the volcanic eruption mode is compound (central + fissure type) eruption; magma erupts along fissures in a certain direction, and the volcanic craters are linearly distributed along the fault. This kind of eruption is mostly formed by basic rocks; the ejected lava is distributed in a gentle and large area, forming typical lava sheets, lava flows, lava waterfalls, etc.

[0200] During the c Yingshan Formation sedimentary period, affected by the third episode of the Yanshan Movement, the regional stress field changed from tensile to compressive, faults developed, accompanied by volcanic revival and eruption, and volcanic rocks, intrusive rocks, and volcanic clastic rocks developed. At the same time, the entire strata were uplifted and eroded, forming the largest unconformity surface in the whole area.

[0201] Due to the intense tectonic movement in the early and middle Jurassic in the study area, the development scale of volcanic eruptive rocks is relatively large, while the tectonic movement in the late Jurassic is relatively weak, and the volcanic eruption scale is also relatively small. Therefore, the eruption mode of the volcanic rocks in the Yingshan Formation is mainly that the magma first wells up along the fault, then intrudes into the bedrock, undergoes impregnation differentiation in the bedrock, and then extrudes onto the surface for eruption, showing chaotic reflections on the seismic profile.

[0202] 2) Volcanic eruption mode of the Yingshan Formation

[0203] Volcanic eruption styles can be divided into three types according to the shape of the volcanic conduit: central eruption, fissure eruption, and compound (fissure + central, central + middle fissure type) eruption. The volcanic eruption style of the first member of the Yingshan Formation in this area is compound eruption, mainly fissure eruption. The main characteristics are as follows:

[0204] a For central eruption, the volcanic conduit of the volcanic crater is arranged in a bead-like shape along the regional fault zone, concentrated near the major fault zone, and the arrangement pattern is basically consistent with the strike of the major fault, showing the characteristics of central + fissure type distribution. The eruption scale on the top surface of the volcanic rock is relatively large, and the currently known wells are mainly distributed near the volcanic crater. The volcanic eruption mode is as shown in Figure 6 shown.

[0205] b The volcanic crater is obvious, the eruption energy is strong, and the main eruption is explosive. The main lithology is volcanic clastic rock, followed by lava.

[0206] c An obvious volcanic crater can be seen on the seismic profile. The external shape of the reflection structure is mound-shaped, and its internal part shows chaotic reflections or weak blank reflections. There are obvious faults or fractures below the volcanic crater.

[0207] During the fault period, the tectonic movement was intense, the fissures developed, and the magma surged up along the basement fissures and erupted on the surface, forming tall volcanic rock accumulations and uplift areas near the crater. Figure 7 shown.

[0208] The Ying 1 volcanic channel has multiple phases of activity, with fissure eruptions in the early stage and central eruptions in the middle and late stages. The plane is distributed in a beaded pattern along the Xuxi Fault. Figure 7 shown.

[0209] After completing the volcanic channel identification and eruption mode analysis, the volcanic body characterization process is carried out. The specific process is as follows:

[0210] 1. Volcanic body calibration

[0211] The key and basis for volcanic body identification is to calibrate the volcanic rock bodies encountered by known wells on the seismic profile. The accuracy of volcanic body layer calibration is directly related to the success or failure of reservoir prediction, and it is also a bridge connecting seismic, well logging and geology. Only with accurate calibration can it be possible to use multiple seismic information to more accurately describe the geometric morphology and reservoir parameters of the reservoir. Synthetic records were used to finely calibrate the volcanic bodies of all wells that encountered the volcanic rocks of Yingyi Section in the study area.

[0212] 2. Identification of volcanic body profile

[0213] The volcanic body profile identification mainly uses the reflection feature difference of seismic post-stack profile, three-moment profile and pure wave profile. In the specific interpretation process, in view of the fact that some volcanic body profile features are small and difficult to identify, local special display and 3D visualization are used for identification.

[0214] After the horizon was calibrated using the above method, the top and bottom surfaces of the Yingyi volcanic rock were interpreted in the whole area, and the volcanic bodies formed in different eruption periods were described. From the reflection characteristics of the volcanic bodies calibrated by the well, it can be seen that the reflection characteristics of the volcanic bodies are obviously different due to the differences in lithology and lithofacies.

[0215] 3. Volcano plane recognition

[0216] The plane identification of volcanic rock bodies mainly uses time slices, multi-channel coherent reflection intensity slope slices, and multiple attributes of plane seismic to perform plane extrapolation interpretation based on profile identification. The same volcanic body has similar seismic responses on the plane, and there are obvious differences between different volcanic bodies.

[0217] Due to the multi - stage formation and material diversity of volcanic rocks, they not only have their own special structures on seismic profiles but also have obvious characteristics on horizontal slices. In the first member of the Yingcheng Formation in the Changde area, the reflection amplitudes of volcanic bodies vary greatly. The volcanic bodies near large faults have strong amplitudes, low frequencies, discontinuous and chaotic reflections, which are better identified on horizontal slices. Near the volcanic eruption centers on horizontal slices, the seismic reflections show an irregular vortex - like circular reflection structure. As the depth increases, the circular shape shows an increasing trend of expansion, and it shows a discordant contact with the steep - dip dense band reflections of the Shahezi Formation, with a clear reflection boundary. The volcanic body profile shows strong amplitudes, low frequencies, chaotic and discontinuous reflections, and forms irregular circular chaotic reflections on the plane.

[0218] 4. Results of volcanic body division

[0219] According to the above - mentioned volcanic body characterization process, a total of 13 volcanic bodies have been identified in the study area of this application (refer to Figure 8 shown), mostly single - source and single - stage volcanoes, with large thickness differences. Small - scale volcanic bodies are mostly developed in the FS6 block. There is only an overlap at the edge of Volcano 3 and Volcano 12, and the reflection characteristics of each volcanic body at the overlap are different.

[0220] A total of 13 volcanic bodies have been identified in the study area, mostly small - scale volcanic bodies, with a total area of 155.09 km 2 . The area of a single volcanic body is between 0.75 and 70.76, generally about 3 km 2 ; the amplitude is between 90 - 540 m, generally about 200 m; the burial depth is between - 2980 and - 3780 m, generally about 3400 m. Among them, 7 volcanic bodies have no well penetration, with a total area of 15.74 km 2 ; 3 volcanic bodies have 1 well penetration, with a total area of 22.45 km 2 ; 3 volcanic bodies have multiple well penetrations, with a total area of 116.9 km 2 (refer to Table 7 below). The scale of each volcanic body is small, and the thickness difference is large. The thickness of the volcanic body is between 32 and 160 m, with an average of about 70 m.

[0221] Table 7 Statistical table of volcanic body structural elements

[0222]

[0223]

[0224] After completing the characterization of volcanic bodies, it is necessary to further complete the planar facies characterization of volcanic rocks. The lithology and lithofacies of volcanic rocks are complex, and the classification methods vary. The more widely used classification scheme is the 5 - facies and 15 - sub - facies classification. Four types of facies belts (volcanic sedimentary facies, effusion facies, explosive facies, and volcanic conduit facies) are developed in the Changde area.

[0225] There are many methods for dividing volcanic rock facies. For different geological backgrounds and research purposes, the criteria for facies division are also different. The core of this application is to predict the development location of favorable volcanic rock reservoirs. For volcanic rock facies, more attention is paid to the facies belts where volcanic rock reservoirs develop. The volcanic rocks in the deep fault depression of Changde area show fissure-center type eruptions. The facies belts with better reservoir physical properties are mostly located in the positive construction positions of volcanic bodies. The volcanic crater and proximal facies belts are the facies belts where the facies development of reservoir prediction focuses on. Therefore, the plane prediction of volcanic rock facies in this project adopts the division scheme of crater facies, proximal facies and distal facies, and combines the single-well gas test results and seismic prediction results to further divide the explosion facies class I, class II and overflow facies class I, class II within the proximal facies. This division scheme is more conducive to showing the distribution law of volcanic bodies on the plane and facilitating the prediction and summary of the distribution and development law of volcanic rock reservoirs. The division process of volcanic rock facies is as follows:

[0226] First, use multi-channel coherent average energy slices to depict the volcanic conduit facies. In the study of strata in this application, it is found that the volcanic crater shows a chaotic circular display on multi-channel coherent average energy slices, and its development range is depicted using this to depict the volcanic conduit facies.

[0227] Second, use multi-channel coherent reflection intensity slope slices to clarify the main development positions of volcanic bodies. There are similar seismic responses of the same volcanic body on the plane, and there are obvious differences between different volcanic bodies.

[0228] Third, combine the volcanic body depiction results and effective reservoir prediction results to conduct proximal facies depiction. The proximal facies is located within the development range of volcanic bodies and effective volcanic rock reservoirs.

[0229] Fourth, taking the single-well facies division results as the main basis and combining multi-channel coherent reflection slope intensity slices, depict the distribution areas of explosion facies and overflow facies within the proximal facies. The same facies has similar seismic responses on the plane.

[0230] Fifth, use the well-point volcanic rock facies sensitive attributes to guide the optimization of plane attributes. First, use the attribute waveform clustering method to divide the volcanic rock plane facies (explosion facies, overflow facies, volcanic conduit facies and volcanic sedimentary facies) corresponding to each target layer and single well. On the basis of the above division results, carry out targeted optimization of plane Seino waveform clustering parameters and extraction of clustering attributes. Combine well-seismic and plane-profile to optimize the Seino plane facies sensitive attributes. Therefore, this application conducts "lithology - fabric - genesis" facies depiction (explosion facies, overflow facies, volcanic conduit facies and volcanic sedimentary facies) based on the Seino waveform clustering plane sensitive attributes, and depicts the "lithology - fabric - genesis" facies of each small layer of the first member of the Yingcheng Formation respectively. Using the Seino waveform clustering plane sensitive attributes and combining with the single-well gas test productivity, depict class I and class II facies belts within the explosion facies and overflow facies.

[0231] Through the integration of multiple types of information, the "volcanic rock facies" conversion is carried out for each small layer of the first member of the Yingcheng Formation respectively. The gas-producing wells and wells with good shows in each layer are all located in the development ranges of the volcanic conduit facies, explosive facies type I, and overflow facies type I. These facies belts are favorable facies belts for gas-bearing, that is, the final planar facies belts of the volcanic rocks.

[0232] The above-described embodiments are only for expressing the implementation manners of the present disclosure. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on the patent scope of the present disclosure. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present disclosure, several deformations, equivalent substitutions, improvements, etc. can be made, and these all belong to the protection scope of the present disclosure. Therefore, the protection scope of the patent of the present disclosure shall be subject to the appended claims.

Claims

1. A method for depicting volcanic bodies based on the slope attribute of multi-channel coherent reflection intensity, characterized in that Comprising: Obtaining the seismic-geological profile characteristics corresponding to each geological layer of the volcanic body in the study area; Based on the seismic-geological profile characteristics and the multi-channel coherent average energy slice of the volcanic body in the study area, depicting the volcanic conduit facies of the volcanic body in the study area and determining the development range of the volcanic conduit facies.

2. The method for depicting a volcanic body according to claim 1, wherein: The method for determining each geological layer of the volcanic body in the study area includes: Using the logging data, well logging data and 3D seismic data of the volcanic rocks in the study area, based on the lithological combination characteristics of the regional standard well, taking the electrical cycle characteristics as the basis, dividing the gas layer groups in the volcanic body by the combined well logging curve characteristic comparison method, constructing an isochronous stratigraphic correlation framework combining well and seismic in the study area according to the division results, and determining each geological layer of the volcanic body in the study area through the isochronous stratigraphic correlation framework; and / or, The method for obtaining the seismic-geological profile characteristics corresponding to each geological layer of the volcanic body in the study area includes: Performing well-seismic layer adjustment on each geological layer of the volcanic body in the study area, calibrating the seismic layers after adjustment, and determining the seismic-geological profile characteristics corresponding to each geological layer of the volcanic body in the study area.

3. The method for depicting a volcanic body according to claim 2, wherein The method for determining the seismic-geological profile characteristics corresponding to each geological layer of the volcanic body in the study area includes: According to the well-seismic combined connecting well profile, adjusting the stratification depth between each geological layer according to a unified stratification standard among wells to obtain the adjusted geological layers; Based on the seismic-geological profile and the drilling stratification results, using well logging information to perform artificial synthetic record calibration on the target wells in the adjusted geological layers to obtain the seismic reflection wave group characteristics corresponding to each geological interface; and determining the seismic-geological profile characteristics corresponding to each geological layer of the volcanic body in the study area according to the seismic reflection wave group characteristics.

4. The method for depicting a volcanic body according to any one of claims 1 to 3, characterized in that, The method for depicting the volcanic conduit facies of the volcanic body in the study area and determining the development range of the volcanic conduit facies includes: Based on the geological layers of the volcanic body in the study area, using the volcanic crater profile interpretation technique to identify the volcanic crater profile, extracting the profile characteristics of the volcanic conduit on the seismic-geological profile, and determining the location of the volcanic crater; Obtaining the coherent data volume of the geological layers of the volcanic body, extracting the multi-channel coherent average energy slice from the coherent data volume, and obtaining the planar distribution characteristics of the volcanic crater and the volcanic conduit through the multi-channel coherent average energy slice; According to the planar distribution characteristics of the volcanic crater and the volcanic conduit, the profile characteristics of the volcanic conduit and the location of the volcanic crater, performing 3D visualization interpretation on the geological layers of the volcanic body to obtain the spatial distribution characteristics of the volcanic crater and the volcanic conduit, and determining the development range of the volcanic conduit facies according to the spatial distribution characteristics of the volcanic crater and the volcanic conduit.

5. The volcanic body characterization method according to claim 4, wherein Further comprising: Obtaining the multi-channel coherent reflection intensity slope attribute of the volcanic body, and combining the seismic-geological profile characteristics to determine the volcanic body profile characteristics, volcanic body planar characteristics and main development locations of the volcanic body in the study area.

6. The method for depicting a volcanic body according to claim 5, characterized in that, The method for determining the volcanic body profile characteristics includes: Based on the characteristic data of the volcanic rock mass encountered in the known wells in the study area, horizon calibration of the volcanic rock mass is carried out on the seismic geological section; based on the horizon calibration results of the volcanic rock mass, volcanic body profile interpretation is carried out, and the volcanic body profile is identified according to the reflection characteristic differences of the post-stack seismic profile, triple transient profile and pure wave profile, and the characteristics of the volcanic body profile are obtained.

7. The method for depicting a volcanic body according to claim 6, wherein, The method for determining the planar characteristics of the volcanic body and the main development positions of the volcanic body includes: Carrying out extrapolation interpretation of the volcanic body plane on the volcanic body profile to obtain the planar characteristics of the volcanic body; Based on the coherent data volume of the geological stratification of the volcanic body, multi-trace coherent reflection intensity slope slicing processing is carried out to obtain the multi-trace coherent reflection intensity slope attribute of the volcanic body; Combining the characteristics of the volcanic body profile and the planar characteristics of the volcanic body, volcanic body identification is carried out on the seismic geological section, and referring to the multi-trace coherent reflection intensity slope attribute and combining the seismic reflection characteristics of the profile, the main development positions of the volcanic body are determined.

8. The method for depicting a volcanic body according to any one of claims 5-7, characterized in that, It also includes: Carrying out effective reservoir prediction on the geological stratification of the volcanic body to obtain effective reservoir prediction results; Based on the development range of the volcanic conduit facies and the main development positions of the volcanic body, combined with the effective reservoir prediction results, the volcanic body is divided into crater-near crater facies, proximal facies and distal facies to determine the development range of the volcanic facies belt in the study area.

9. The method for depicting a volcanic body according to claim 8, wherein It also includes: Based on the single-well facies division results of the volcanic body in the study area, combined with the multi-trace coherent reflection slope intensity slice, the distribution areas of the explosive facies and the overflow facies are delineated within the proximal facies, and multi-attribute clustering analysis is carried out in combination with the sensitive attributes of the volcanic rock facies to delineate the planar facies belt of the volcanic rock in the study area.

10. The method for depicting a volcanic body according to claim 9, wherein The method for carrying out multi-attribute clustering analysis to delineate the planar facies belt of the volcanic rock in the study area includes: Using the attribute waveform clustering method to carry out the multi-attribute clustering analysis, and using the attribute waveform clustering method to divide the volcanic rock planar facies corresponding to each target layer and the single well of the volcanic body in the geological stratification; Based on the volcanic rock planar facies, plane Seino waveform clustering parameter optimization and clustering attribute extraction are carried out. Using the plane sensitive attribute of the Seino waveform clustering, combined with the single-well gas test productivity of the volcanic body, the facies belt starting with the explosive facies and the facies belt starting with the overflow facies are delineated inside the distribution areas of the explosive facies and the overflow facies; Based on the facies belt starting with the explosive facies and the facies belt starting with the overflow facies, well-seismic combination is carried out on the volcanic rock planar facies to delineate the planar facies belt of the volcanic rock in the study area.

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