Material source comprehensive discrimination method suitable for complex clastic rock system

Abstract

The invention discloses a comprehensive source discrimination method suitable for a complex clastic rock system, and relates to the technical field of petroleum and natural gas exploration and development. According to the method, the space imaging advantage of three-dimensional seismic data of a research work area on an underground geologic body is fully utilized, and the material source of a complex clastic rock system is comprehensively judged by recognizing the carrying process of sedimentary substances and combining the datum plane cycle, logging facies and rock facies achievements. According to the method, the carrying process of the sediment can be more effectively highlighted, and interpretation personnel can be helped to more effectively clarify a material source system. The method disclosed by the invention is suitable for comprehensive distinguishing research on the material sources of the complex clastic rock system, and is expected to be applied to lithofacies paleogeography recovery and mineral resource development of a multi-material-source system basin.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas exploration and development, and more particularly to a comprehensive source identification method suitable for complex clastic rock systems. Background Art

[0002] The distribution of sedimentary phases reflects the spatial combination of sedimentary rocks, records the filling process of the basin, is formed by physical, chemical and biological causes, accurately records paleoclimate and paleoenvironmental information, and can reflect the direction of sediment transportation to a certain extent.

[0003] The transportation of clastic sediments is controlled by mechanical differentiation. Coarse clastic materials will be deposited first, while silt and mud will be transported to longer distances. Therefore, the direction of decrease in sandstone percentage (sand / ground ratio) can also reflect the direction of sediment transportation.

[0004] The analysis of paleocurrent (paleoflow direction) mainly relies on the partial sedimentary structures of flow genesis and the spatial variation of river morphology to indicate the source. The characteristics of the clastic components such as quartz, feldspar, rock fragments and heavy minerals in sandstone are the ultimate reflection of the provenance area under the control of the tectonic background and transportation history. The sandstone clastic assemblage contains the parent rock properties of the provenance area and the tectonic background information of the provenance area. The changes in the light and heavy mineral assemblage in sandstone samples and the ZTR index of heavy minerals can be used to reflect the climate of the provenance area and the information of the transportation route and distance. The nature, scale and age of magmatic events can record the tectonic background of magmatic rocks, and the products of multi-stage intrusive rocks or volcanic rocks are transported and deposited and preserved in clastic rocks. Among them, zircon can preserve the multi-stage magmatic records of the provenance area due to its high closure temperature and stable properties. At the same time, the Hf isotope composition can provide constraints on the nature of the provenance area and the source of magma.

[0005] The above methods require the collection of a large number of rock samples, especially drilling cores. Only through detailed field investigations, core observations and a large number of indoor analysis tests can the provenance of the study area be studied and analyzed more accurately. However, when faced with a multi-provenance system, especially in the provenance intersection zone, conventional analysis methods often cannot effectively distinguish different provenance directions, so there is a certain degree of multi-solution. Provenance analysis is the basis for the restoration of lithofacies and paleogeography in sedimentary basins, which directly affects the understanding of the distribution law of sand bodies and thus affects the direction of oil and gas exploration. Taking the Xujiahe Formation of the Upper Triassic in the Sichuan Basin as an example, the Late Triassic is an important evolutionary stage of the Sichuan Basin. There are multiple paleo-continents or uplift areas around the basin. Its provenance area and provenance composition are extremely complex, especially in the transition zone between western Sichuan and central Sichuan. There may be multiple provenance intersections, which brings huge challenges to provenance analysis. Summary of the invention

[0006] In order to overcome the defects and shortcomings in the above-mentioned prior art, the present invention provides a comprehensive provenance identification method suitable for complex clastic rock systems. The purpose of the present invention is to solve the problem that when facing a multi-provenance system, especially in the provenance intersection zone, the existing conventional analysis methods cannot effectively distinguish different provenance directions and have certain multi-solutions. The present invention makes full use of the spatial imaging advantages of the three-dimensional seismic data of the research area for underground geological bodies, and comprehensively judges the provenance of complex clastic rock systems by identifying the transportation process of sedimentary materials and combining the base level cycle, logging phase and rock phase results. The present invention can more effectively highlight the sediment transportation process and help interpreters to clarify the provenance system more effectively. The present invention is suitable for the comprehensive identification of the provenance of complex clastic rock systems, and is expected to be used in the restoration of lithofacies paleogeography and mineral resource development in basins with multiple provenance systems.

[0007] In order to solve the above problems existing in the prior art, the present invention is implemented through the following technical solutions.

[0008] The present invention discloses a comprehensive source identification method applicable to a complex clastic rock system, the method comprising the following steps: S1. Obtain 3D seismic data of the study area, complete horizon calibration on the 3D seismic data of the study area, and implement the chronostratigraphic significance of the seismic horizon; S2. Searching for seismic reflection structures that can indicate the source of sediments on the seismic profile according to the sediment filling process; S3. Combine well logging and lithological characteristics of the research area to analyze the material composition of different provenance areas, and identify the logging response characteristics of different provenances through calibration of well logging and cores; S4. Use seismic reflection characteristics to determine the macroscopic distribution characteristics of the source system and the sediment intersection area in the research area; S5. Combine logging phase and lithofacies results to make a detailed identification of multiple provenance systems and their control ranges in the study area.

[0009] Further preferably, step S1 implements the chronostratigraphic significance of the seismic layer, specifically refers to tracking and comparing all seismic phase axes in the target layer through full-layer tracking technology, identifying the stratigraphic interface and dividing the seismic sequence in combination with logging and lithological data; on the basis of the divided seismic sequence, determining the time stratigraphic unit of the sedimentary layer by utilizing seismic detection methods; wherein the seismic sequence corresponds to the sedimentary sequence and is the reflection of the sedimentary sequence on the seismic profile.

[0010] More preferably, dividing the seismic sequence specifically means finding two adjacent unconformity surfaces on the seismic section and tracing them to the conformity surfaces respectively, then the whole set of strata between the two conformity surfaces is a complete seismic sequence.

[0011] More preferably, the top boundary relationship of the seismic sequence includes three types: erosion, onlap and conformity, and the bottom boundary relationship of the seismic sequence includes three types: onlap, onlap and conformity.

[0012] More preferably, the seismic detection method is a seismic detection method that integrates seismic wave group characteristics.

[0013] Further preferably, in step S2, the seismic reflection structure capable of indicating the provenance includes a progradational / lateral depositional structure, an incised channel structure and a provenance intersection structure.

[0014] More preferably, the progradational / lateral accretionary structures mainly develop two types of progradational / lateral accretionary structures, namely, S-type and imbricate progradational / lateral accretionary structures; wherein, the S-type progradational / lateral accretionary structure means relatively low sediment supply, relatively rapid basin subsidence or rapid sea level rise, which enables the top accumulation layer to be deposited and preserved, and is interpreted as a relatively low-energy depositional mechanism; Imbricate progradational / lateral accretionary structures, indicating relatively high sediment supply rates, slow or no basin subsidence, and a quiescent sea level that combined to some extent to rapidly fill the basin and allow subsequent sedimentary currents to pass over or scour the upper sedimentary surface, indicate a relatively high-energy sedimentary structure; The downlap direction of the S-type and imbricate progradational / lateral accretionary structures indicates the sediment collection area, while the uplap direction indicates the location of the provenance area.

[0015] More preferably, the incised channel structure is characterized by a concave bottom event axis in the shape of a "U" or "V", and some incised channels have filling features with overhangs at both ends; the width of the river gradually increases from the provenance area to the confluence area; the spatial change pattern of the channel can indicate the location of the provenance area.

[0016] More preferably, the provenance intersection structure means that in a basin with multiple provenances, multiple provenance systems converge simultaneously in a certain area, which is the provenance intersection area; it appears as discontinuity of event axes on the seismic profile, with one or more groups of event axes overlapping downward or oppositely; a group of event axes in the same direction represents the same provenance, and event axes in different directions represent different provenance systems; the downward overlapping direction of the event axes indicates the direction of the basin, and the upward overlapping direction of the event axes indicates the direction of the provenance area.

[0017] More preferably, during the period of base level rise, the sediments retrograded toward the provenance, and their seismic reflections showed the characteristics of onlapping toward the provenance area, while during the period of base level drop, the sediments prograded toward the basin, and their seismic reflections showed the characteristics of onlapping toward the basin; near the provenance intersection area, during the period of base level rise, the event axes on the seismic profile near the provenance intersection area mainly showed the characteristics of anti-onlapping, while during the period of base level drop, the event axes on the seismic profile near the provenance intersection area mainly showed the characteristics of opposite onlapping.

[0018] Compared with the prior art, the beneficial technical effects brought by the present invention are as follows: 1. The present invention adopts the provenance analysis technology based on sequence stratigraphy theory and seismic information, describes the distribution direction of the ancient river channel according to the information such as seismic reflection structure and filling characteristics, adopts the full-layer tracing method to identify the stratigraphic overlap points, and identifies the different provenance systems in the basin.

[0019] 2. The present invention will provide a new method for the provenance analysis of complex clastic rock systems. Compared with traditional provenance analysis methods based on sedimentary rock component characteristics, phase belt distribution patterns, and sandstone percentage change trends, this method can more effectively highlight the sediment transportation process and help interpreters to more effectively clarify the provenance system. The present invention is suitable for comprehensive provenance identification research of complex clastic rock systems, and can also be used in areas where coring data and geochemical analysis data are scarce. It is expected to be used in lithofacies paleogeographic restoration and mineral resource development in basins with multiple provenance systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The result map of seismic sequence division; Figure 2 This is the TS1 well-seismic comparison diagram; Figure 3 This is the XS1-well-seismic comparison chart; Figure 4 This is the well-seismic comparison diagram of FS1 and Q1; Figure 5 Well-seismic comparison of the fourth segment is required for the QL2 well Figure 1 ; Figure 6 Well-seismic comparison of the fourth segment is required for the QL2 well Figure 2 ; Figure 7 This is the well-seismic comparison diagram of the Xujiahe Formation in Well QL2; Figure 8 Well-seismic comparison diagram of Xujiahe Formation in Well TN102 and Well TN6; Fig. 9 This is the well-seismic comparison diagram of Xujiahe Formation in Well GA12; Fig.10 Reflection characteristics of the seismic section in the source intersection zone Figure 1 ; Fig.11 Reflection characteristics of the seismic section of the source intersection zone Figure 2 ; Fig.12 Reflection characteristics of the seismic section in the source intersection zone Figure 3 ; Fig.13 Reflection characteristics of the seismic section in the source intersection zone Figure 4 ; Fig.14 Reflection characteristics of the seismic section in the source intersection zone Figure 5 ; Fig.15 Reflection characteristics of the seismic section in the source intersection zone Figure 6 ; Fig.16 This is a thin section characteristic map of the Xujiahe Formation rock at the Gongnongzhen section in Guangyuan; Fig.17 This is a thin section characteristic map of the Xujiahe Formation rock at the Shishan section in Pengzhou; Fig.18 This is the characteristic diagram of the thin section of Xujiahe rock in Jinhe section of Shifang; Fig.19 This is the thin section characteristic map of Xujiahe Formation in Pingxi, Tongjiang; Fig. 20 This is a thin section characteristic map of the Jiahe Formation in Guojiaba, Zigui; Fig.21 This is the characteristic map of the rock thin section of Xujiahe Formation in Luojiachang, Changshou; Fig. 22 This is the thin section characteristic map of the Xujiahe Formation in the Shaping section of Dianjiang; Fig.23 This is the characteristic map of the rock thin section of Xujiahe Formation in Shizhu Lengshui and Moudao sections; Fig.24 This is the characteristic map of the rock thin section of Xujiahe Formation in Yangcunpu, Emei; Fig.25 This is the characteristic map of the rock thin section of the Xujiahe Formation in Qiqiu, Bijie; Fig.26 This is the characteristic diagram of the well logging curve of the coring section of the Xujiahe Formation in Well QL7; Fig. 27 The well logging curve characteristics of the coring section of the Xujiahe Formation in Well PL7; Fig.28 This is a comparison of the sand bodies of the second section of Xuzhou Well QL13-JH8 Well; Fig.29 It is a full-layer tracing section of the seismic data volume; Fig.30 It is the characteristic map of S-shaped foreset / lateral settling structure of seismic data volume; Fig.31 It is the characteristic map of the imbricate progradational / lateral gradational structure of the seismic data volume; Fig.32 It is a "U"-shaped reflection feature and spatial evolution morphology diagram; Fig.33 This is the characteristic diagram of seismic event axes in the source intersection area; Fig.34 Direction of material transport indicated for progradational / lateral gradational structures; Fig.35It is the result of comprehensive judgment on the provenance of the complex clastic rock system. DETAILED DESCRIPTION

[0021] The following is an exemplary embodiment of the present invention that helps to fully understand the claims and their equivalents in conjunction with the accompanying drawings, wherein the specific details will be considered as exemplary only, and do not limit the scope of the present invention. Therefore, those of ordinary skill in the art can make various changes and modifications to the embodiments without departing from the scope and spirit of the present invention.

[0022] Example 1 As a preferred embodiment of the present invention, this embodiment discloses a comprehensive provenance identification method applicable to a complex clastic rock system, the method comprising the following steps: S1. Obtain 3D seismic data of the study area, complete horizon calibration on the 3D seismic data of the study area, and implement the chronostratigraphic significance of the seismic horizon; S2. Searching for seismic reflection structures that can indicate the source of sediments on the seismic profile according to the sediment filling process; S3. Combine well logging and lithological characteristics of the research area to analyze the material composition of different provenance areas, and identify the logging response characteristics of different provenances through calibration of well logging and cores; S4. Use seismic reflection characteristics to determine the macroscopic distribution characteristics of the source system and the sediment intersection area in the research area; S5. Combine logging phase and lithofacies results to make a detailed identification of multiple provenance systems and their control ranges in the study area.

[0023] In this embodiment, the spatial imaging advantage of the three-dimensional seismic data in the basin for underground geological bodies is fully utilized, and the provenance of the complex clastic rock system is comprehensively judged by identifying the transportation process of sedimentary materials and combining the base level cycle, logging phase and rock phase results.

[0024] Example 2 As another preferred embodiment of the present invention, this embodiment further elaborates and supplements the technical solution of the present invention on the basis of the above-mentioned embodiment 1. In this embodiment, the chronostratigraphic significance of the seismic layer is implemented, specifically, all seismic phase axes in the target layer are tracked and compared through the full-layer tracking technology, and the sequence interface is identified and the seismic sequence is divided by combining the logging and lithological data; on the basis of the divided seismic sequence, the time stratigraphic unit of the sedimentary layer is determined by using the seismic detection method; wherein the seismic sequence corresponds to the sedimentary sequence and is the reflection of the sedimentary sequence on the seismic profile.

[0025] To divide the seismic sequence specifically means to find two adjacent unconformity surfaces on the seismic section and trace them to the conformity surfaces respectively. The whole set of strata between the two conformity surfaces is a complete seismic sequence.

[0026] The top boundary relationship of the seismic sequence includes three types: erosion, onlap and conformity, and the bottom boundary relationship of the seismic sequence includes three types: onlap, onlap and conformity.

[0027] The above-mentioned earthquake detection method is an earthquake detection method that integrates the characteristics of seismic wave groups.

[0028] Example 3 As another preferred embodiment of the present invention, this embodiment further elaborates and supplements the technical solution of the present invention on the basis of the above-mentioned embodiment 1 or embodiment 2. In this embodiment, in the above-mentioned step S2, the seismic reflection structure capable of indicating the source includes the progradational / lateral accretionary structure, the incised channel structure and the source confluence structure.

[0029] Among them, the progradational / lateral accumulation structures mainly develop two types of progradational / lateral accumulation structures, namely S-type and imbricate. Among them, the S-type progradational / lateral accumulation structure means relatively low sediment supply, relatively rapid basin subsidence or rapid sea level rise, which allows the top accumulation layer to be deposited and preserved, and is interpreted as a relatively low-energy depositional mechanism; the imbricate progradational / lateral accumulation structure indicates a relatively high sediment supply rate, slow or no basin subsidence and a stationary sea level that, to some extent, combined to rapidly fill the basin and allow subsequent sedimentary water flows to pass by or scour the upper sedimentary surface, indicating a relatively high-energy depositional structure; the downlap direction of the S-type and imbricate progradational / lateral accumulation structures indicates the sediment collection area, while the uplap direction indicates the location of the provenance area.

[0030] The structure of the incised channel is characterized by a concave bottom event axis in the shape of a "U" or "V". In some incised channels, filling features with overhangs at both ends can be seen. From the provenance area to the confluence area, the width of the river gradually increases. The spatial change pattern of the channel can indicate the location of the provenance area.

[0031] The provenance intersection structure means that in a basin with multiple provenances, multiple provenance systems converge simultaneously in a certain area, which is the provenance intersection area. It is manifested as the discontinuity of event axes on the seismic profile, with one or more groups of event axes overlapping downward or oppositely. A group of event axes in the same direction represent the same provenance, while event axes in different directions represent different provenance systems. The downward overlapping direction of the event axes indicates the direction of the basin, and the upward overlapping direction of the event axes indicates the direction of the provenance area.

[0032] During the period of base level rise, sediments retrograded toward the provenance, and their seismic reflections showed the characteristics of onlapping toward the provenance area, while during the period of base level drop, sediments prograded toward the basin, and their seismic reflections showed the characteristics of onlapping toward the basin area; near the provenance intersection area, during the period of base level rise, the event axes on the seismic profile near the provenance intersection area mainly showed the characteristics of anti-onlapping, while during the period of base level drop, the event axes on the seismic profile near the provenance intersection area mainly showed the characteristics of anti-onlapping.

[0033] Example 4 As another preferred embodiment of the present invention, the comprehensive provenance identification method applicable to complex clastic rock systems disclosed in the present invention is described in detail below in combination with specific examples and drawings of the specification.

[0034] This embodiment makes full use of the spatial imaging advantage of the three-dimensional seismic data in the basin for underground geological bodies, and comprehensively judges the source of the complex clastic rock system by identifying the transportation process of sedimentary materials and combining the results of base level cycles, logging phases and rock phases.

[0035] The first step is to complete the layer calibration on the 3D seismic data and implement the chronostratigraphic significance of the seismic layer. Through the full layer tracking technology, all seismic phase axes in the target layer are tracked and compared. Combined with logging and lithology data, the sequence interface is identified and the seismic sequence is divided (see the attached manual). Figure 1 as shown).

[0036] Seismic sequences determine the time stratigraphic units of sedimentary layers by using seismic detection methods such as integrated seismic wave group characteristics. Seismic sequences correspond to sedimentary sequences and are the reflection of sedimentary sequences on seismic sections. On a seismic section, find two adjacent unconformities and trace them to the conformity surfaces. The complete set of strata between the two conformity surfaces is a complete seismic sequence. The top boundary relationships of seismic sequences include erosion, onlap and conformity. The bottom boundary relationships of seismic sequences include onlap, onlap and conformity.

[0037] The second step is that the seismic phase is the sum of the manifestations of the sedimentary phase on the seismic section. It is a seismic feature formed by the sedimentary environment (such as marine or continental phase). It refers to a seismic reflection unit within a certain area. The seismic attribute parameters within this unit are different from those of the adjacent units. It represents the lithological combination, bedding and sedimentary characteristics of the sediments that produce its reflection. Therefore, the shape, internal structure, top and bottom contact relationship, amplitude, continuity, apparent period, layer velocity and lateral changes of reflection characteristics of the seismic phase can be used to identify the lithology of the geological body and its internal structural characteristics, and then infer the sedimentary environment and sedimentary transportation direction.

[0038] According to the sediment filling process, the seismic reflection structure that can indicate the source is searched on the seismic profile, such as the progradational / lateral accretionary structural characteristics, "U"-shaped reflection characteristics and cross-type filling characteristics. The specific steps are as follows: Identification of seismic response characteristics of sand bodies: Identify the seismic response characteristics of sand bodies through calibration of seismic synthetic records. Take the Xujiahe Formation in the western Sichuan-central Sichuan region of the Sichuan Basin as an example. It was found that in the western Sichuan region, the seismic reflection characteristics of thick sandstone (single layer thickness is generally >20m) are mainly strong troughs, and the continuous troughs show the characteristics of "transparent phase", which are generally the reflection of relatively continuous sandstone sections. This feature is most obvious in the Xujiahe Formation. The stably distributed strong peaks are usually the reflection of continuous and relatively pure mudstone sections (as shown in the attached manual). Figure 2 and attached Figure 3 as shown).

[0039] In the central Sichuan area, sandstone also mainly presents the seismic reflection characteristics of troughs, especially in the Xu 2nd and Xu 4th members. Strong troughs are usually the reflection of continuous thick sand bodies, and strong troughs sandwiched with weak peaks are usually the reflection of thick continuous sand bodies sandwiched with thin mudstones (see Appendix Figure 4 , Attachment Figure 5 and attached Figure 6 The pure mudstone section also shows a stable strong peak reflection (see the attached manual). Figure 7 , Attachment Figure 8 and attached Fig. 9 as shown).

[0040] Characteristics of progradational / lateral accumulation structures: There are two main progradational / lateral accumulation structures: S-shaped and imbricate. S-shaped progradational / lateral accumulation structure: It means relatively low sediment supply, relatively rapid basin subsidence or rapid sea level rise, which allows the top accumulation layer to be deposited and preserved, and is interpreted as a relatively low-energy depositional mechanism. Imbricate progradational / lateral accumulation structure: Relatively high sediment supply rate, slow or no basin subsidence and a stationary sea level are combined to a certain extent to quickly fill the basin, and make the subsequent sedimentary water flow pass by or wash the upper sedimentary surface, indicating a relatively high-energy depositional structure. These two progradational / lateral accumulation structures are the gathering areas of sediments in the downlap direction, while the uplap direction indicates the location of the source area.

[0041] Downcut channels are characterized by a concave bottom phase axis, in the shape of a "U" or "V". Some downcut channels have filling features with both ends on top. From the source area to the confluence area, the width of the river gradually increases. The spatial change pattern of the river channel can indicate the location of the source area.

[0042] During the period of base level rise, sediments are retrograded toward the source, and their seismic reflections show the characteristics of onlapping toward the source area; while during the period of base level decline, sediments are prograded toward the basin, and their seismic reflections show the characteristics of onlapping toward the basin. Therefore, near the source intersection area, during the period of base level rise, the phase axis on the seismic section near the source intersection zone mainly shows the characteristics of anti-onlap, while during the period of base level decline, the phase axis on the seismic section near the source intersection zone mainly shows the characteristics of anti-onlap.

[0043] In a basin with multiple provenances, multiple provenance systems converge in a certain area at the same time, that is, the provenance intersection area. On the seismic profile, it is manifested as discontinuity of event axes, one or more groups of event axes overlap downward (during the period of base level decline) or overlap inversely (during the period of base level rise). A group of events in the same direction represents the same provenance, while events in different directions represent different provenance systems. The downlap direction of the event axis indicates the direction of the lake basin, and the uplap direction of the event axis indicates the direction of the provenance area.

[0044] In the central and western Sichuan regions, on the northwest-southeast seismic profile, obvious upthrust from northwest to southeast and upthrust from southeast to northwest can be seen (anti-upthrust, as shown in the attached manual). Fig.10 ~Attached Fig.14 ), reflecting that the two major delta sedimentary systems in the east and west regressed towards the source during the period of base level rise; or they were downlapping from northwest to southeast and downlapping from southeast to northwest (for uplapping, see the attached manual Fig.15 (as shown in the figure), reflecting that the eastern and western delta sedimentary systems prograded towards the basin during the period of base level decline.

[0045] Step 3: Combine logging and lithology characteristics to analyze the material composition of different provenance areas, and identify the logging response characteristics of different provenances through logging and core calibration. For example, in the Xujiahe Formation in the Sichuan Basin, different provenance systems have different rock fragment combination characteristics. Western provenance is usually rich in calcareous components, which appear as high resistance on the logging curve. Therefore, logging curve characteristics, such as resistivity curves, can be used as an auxiliary basis for dividing the western provenance system.

[0046] A large number of drilling core data show that there are significant differences in sedimentary components between the western provenance and the eastern, northern and southern provenances of the Xujiahe Formation, mainly in the content of carbonate rock debris. Taking the Pengzhou Shishan section, Shifang Jinhe section and Guangyuan Gongnongzhen section in Longmen Mountain as examples, starting from the Xujiahe Formation 1, the sandstone and conglomerate contain a large amount of carbonate rock debris (see the attached manual). Fig.16 ~Attached Fig.18 ), indicating that the western provenance system was characterized by rich carbonate rock debris throughout the Xujiahe Formation deposition period. Fig.19 ), the eastern edge (Zigui Guojiaba, Fig. 20 ; Changshou Luojiachang, Fig.21 ; Shaping, Dianjiang, Fig. 22 ; Shizhumoudao and Lengshui section, Fig.23 ) and the southern edge (Emei Yangcunpu, Fig.24 ; Seven Hills of Bijie, Fig.25 ; Bijie Mazongling section, Fig.26 ; Yibin Laifudu, Fig. 27 ; Bijie built a new river, Fig.28 ) The content of carbonate rock fragments in the sandstone and conglomerate of the Xujiahe Formation is extremely low.

[0047] From the analysis results of thin sections of sandstone and conglomerate rocks of the Xujiahe Formation in the outcrop sections around the Sichuan Basin, it is not difficult to see that the Xujiahe Formation in western Sichuan generally has a high content of carbonate rock debris, which means that the provenance system in the western Sichuan Basin (including the Pengguan complex and the Motianling paleoland in the Longmenshan area) is characterized by a high content of "calcium debris", and the southwestern Emei-Kangdian paleoland can also provide a small amount of carbonate rock debris, while the Yunnan-Guizhou paleouplift on the southern edge of the Sichuan Basin, the Fanjingshan paleoland, the Xuefengshan paleoland and the eastern Sichuan-Western Hubei paleoland in the southeastern Sichuan, and the Micangshan-Dabashan paleoland on the northern edge did not provide enough carbonate rock debris in the Late Triassic. Generally, only a small amount of "calcium debris" that may come from the paleokarst surface of the Leikoupo Formation is contained in the sandstone at the bottom of the Xujiahe Formation. The carbonate rock debris content in most sandstones of the Xujiahe Formation in central, northern, southern and eastern Sichuan is extremely low. Therefore, considering that the Longmenshan and Motianling paleoland are the main sources of "calcic debris" in the sand and conglomerate of the Xujiahe Formation, the source direction can be traced based on the relative changes in the "calcic debris" content in the sand and conglomerate of the Xujiahe Formation.

[0048] Since the "calcium-clast" sandstone has the characteristics of low GR value, low AC value, low CNL value, high density, and extremely high resistivity value on the well logging curve, the well logging curve characteristics of non-calcium cemented sandstone that almost does not contain carbonate rock cuttings are obviously different, especially characterized by low resistivity ( Fig.26 , Fig. 27 It should be noted that some Xujiahe Formation sandstones have high calcareous cement content, and their logging characteristics are similar to those of "calcareous" sandstones ( Fig. 27 ), so when using logging curves to interpret "calciclastic" sandstone, it is necessary to combine other data for comprehensive analysis.

[0049] According to the well logging interpretation results and the comparison of the well sections, the intersection of the two major provenance systems in the east and west is clearly reflected: the Jinhua-Qiulin area is one of the provenance intersection zones, where the "calcareous sandstone" from the western provenance and the sandstone without calcareous clastics from the eastern provenance meet ( Fig.28 ). It is worth noting that: from the well comparison profile, the intersection of the second section of Xuzhou in the Jinhua-Qiulin area is characterized by the eastern provenance covering the western provenance ( Fig.28), which is completely consistent with the reflection characteristics on the seismic profile, that is, the delta from the western provenance in this area was formed in the early Xu-II period, and then the delta from the eastern provenance system overlapped it.

[0050] Step 4: Use seismic reflection characteristics to determine the macroscopic distribution characteristics of the basin's provenance system and the sediment intersection area. Finally, combine the results of logging phases, lithofacies, etc. to make a detailed identification of the multiple provenance systems in the basin and their control range.

[0051] Example 5 As another preferred embodiment of the present invention, this embodiment takes the provenance analysis of the Xujiahe Formation in the Upper Triassic in Sichuan Basin as an example to illustrate the specific scheme of the present invention.

[0052] First, the layer calibration is completed on the 3D seismic data to implement the chronostratigraphic significance of the seismic layer. Through the full-layer tracking technology, all seismic phase axes in the target layer are tracked and compared. Combined with logging and lithology data, the sequence interface is identified and the seismic sequence is divided ( Fig.29 ).

[0053] Secondly, according to the sediment filling process, search for seismic reflection structures that can indicate the source on the seismic profile, such as progradational / lateral accretionary structural features, "U"-shaped reflection features, and cross-type filling features. The specific steps are as follows: (1) Characteristics of foreset / lateral deposit structure There are mainly two types of foreset / lateral accretion structures: S-shaped and imbricate. Fig.30 and Fig.31 ). S-shaped progradational / lateral accretionary structures: imply relatively low sediment supply, relatively rapid basin subsidence or rapid sea level rise, allowing the top accumulation layers to be deposited and preserved, interpreted as a relatively low-energy depositional mechanism. Imbricate progradational / lateral accretionary structures: relatively high sediment supply rates, slow or no basin subsidence and a stationary sea level combined to some extent to rapidly fill the basin and allow subsequent sedimentary flows to pass over or wash over the upper depositional surface, indicating a relatively high-energy depositional structure. The downlap direction of these two progradational / lateral accretionary structures indicates the sediment collection area, while the uplap direction indicates the location of the source area.

[0054] (2) Downcut channels, characterized by a concave bottom phase axis, in the shape of a "U" or "V". Some downcut channels have filling features with both ends on top. From the source area to the confluence area, the width of the river gradually increases ( Fig.32 ). The spatial variation of the river channel can indicate the location of the provenance area.

[0055] (3) In a basin with multiple provenances, multiple provenance systems converge in a certain area, which is called the provenance intersection area. On the seismic profile, this is manifested as discontinuity of event axes, with one or more groups of event axes overlapping downward (during the period of base level decline) or overlapping backward (during the period of base level rise) ( Fig.33 ). A group of events with the same direction represent the same source, while events with different directions represent different source systems. The downthrust direction of the event indicates the direction of the lake basin, and the upthrust direction of the event indicates the direction of the source area ( Fig.34 ).

[0056] Secondly, the material composition of different provenance areas is analyzed by combining logging and lithological characteristics, and the logging response characteristics of different provenances are identified through the calibration of logging and cores. For example, in the Xujiahe Formation in the Sichuan Basin, different provenance systems have different rock fragment combination characteristics. Western provenance is usually rich in calcareous components, which are shown as high resistivity on the logging curve. Therefore, logging curve characteristics, such as resistivity curves, can be used as an auxiliary basis for dividing the western provenance system.

[0057] The seismic reflection characteristics are used to determine the macroscopic distribution characteristics of the basin's provenance system and the location of the intersection zone. Finally, the multiple provenance systems in the basin and their control ranges are finely identified by combining the results of well logging phases, rock and mineral components, etc. ( Fig.35 ).

[0058] While the inventive concept has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the claims.

Claims

1. A comprehensive provenance identification method applicable to complex clastic rock systems, characterized by: The method comprises the following steps, S1. Obtain 3D seismic data of the study area, complete horizon calibration on the 3D seismic data of the study area, and implement the chronostratigraphic significance of the seismic horizon; S2. Searching for seismic reflection structures that can indicate the source of sediments on the seismic profile according to the sediment filling process; S3. Combine well logging and lithological characteristics of the research area to analyze the material composition of different provenance areas, and identify the logging response characteristics of different provenances through calibration of well logging and cores; S4. Use seismic reflection characteristics to determine the macroscopic distribution characteristics of the source system and the sediment intersection area in the research area; S5. Combine logging phase and lithofacies results to make a detailed identification of multiple provenance systems and their control ranges in the study area.

2. A comprehensive provenance identification method applicable to a complex clastic rock system as claimed in claim 1, characterized in that: Step S1, implement the chronostratigraphic significance of the seismic horizon, specifically, through full-horizon tracing technology, track and compare all seismic phase axes in the target layer, combine well logging and lithology data, identify the sequence interface, and divide the seismic sequence; on the basis of the divided seismic sequence, determine the time stratigraphic unit of the sedimentary layer by using seismic detection methods; Among them, the seismic sequence corresponds to the sedimentary sequence and is the reflection of the sedimentary sequence on the seismic section.

3. A comprehensive provenance identification method applicable to a complex clastic rock system as claimed in claim 2, characterized in that: To divide the seismic sequence specifically means to find two adjacent unconformity surfaces on the seismic section and trace them to the conformity surfaces respectively. The whole set of strata between the two conformity surfaces is a complete seismic sequence.

4. A comprehensive provenance identification method applicable to a complex clastic rock system as claimed in claim 3, characterized in that: The top boundary relationship of the seismic sequence includes three types: erosion, onlap and conformity, and the bottom boundary relationship of the seismic sequence includes three types: onlap, onlap and conformity.

5. A comprehensive provenance identification method applicable to a complex clastic rock system as claimed in claim 2, characterized in that: The seismic detection method is a seismic detection method that integrates the characteristics of seismic wave groups.

6. A comprehensive provenance identification method applicable to a complex clastic rock system according to any one of claims 1 to 5, characterized in that: In step S2, the seismic reflection structures capable of indicating material sources include progradational / lateral accretionary structures, incised channel structures and material source intersection structures.

7. A comprehensive provenance identification method applicable to a complex clastic rock system as claimed in claim 6, characterized in that: The progradational / lateral accretionary structures mainly include two types of progradational / lateral accretionary structures: S-type and imbricate; the S-type progradational / lateral accretionary structure means relatively low sediment supply, relatively rapid basin subsidence or rapid sea level rise, which allows the top accumulation layer to be deposited and preserved, and is interpreted as a relatively low-energy depositional mechanism; Imbricate progradational / lateral accretionary structures, indicating relatively high sediment supply rates, slow or no basin subsidence, and a quiescent sea level that combined to some extent to rapidly fill the basin and allow subsequent sedimentary currents to pass over or scour the upper sedimentary surface, indicate a relatively high-energy sedimentary structure; The downlap direction of the S-type and imbricate progradational / lateral accretionary structures indicates the sediment collection area, while the uplap direction indicates the location of the provenance area.

8. A comprehensive provenance identification method applicable to a complex clastic rock system as claimed in claim 6, characterized in that: The structure of the incised channel is characterized by a concave bottom event axis in the shape of a "U" or "V". In some incised channels, filling features with both ends on top can be seen. From the provenance area to the confluence area, the width of the river gradually increases. The spatial change pattern of the channel can indicate the location of the provenance area.

9. A comprehensive provenance identification method applicable to a complex clastic rock system as claimed in claim 6, characterized in that: The provenance intersection structure refers to a basin with multiple provenances where multiple provenance systems converge simultaneously in a certain area, which is called a provenance intersection area. On the seismic section, it appears as discontinuity of event axes, with one or more groups of event axes overlapping downward or oppositely. A group of events in the same direction represents the same source, while events in different directions represent different source systems. The downward overlapping direction of the event axes indicates the direction of the basin, and the upward overlapping direction of the event axes indicates the direction of the source area.

10. A comprehensive provenance identification method applicable to a complex clastic rock system as claimed in claim 9, characterized in that: During the period of base level rise, sediments retrograded toward the provenance, and their seismic reflections showed the characteristics of onlapping toward the provenance area, while during the period of base level drop, sediments prograded toward the basin, and their seismic reflections showed the characteristics of onlapping toward the basin area; near the provenance intersection area, during the period of base level rise, the event axes on the seismic profile near the provenance intersection area mainly showed the characteristics of anti-onlapping, while during the period of base level drop, the event axes on the seismic profile near the provenance intersection area mainly showed the characteristics of anti-onlapping.

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