Small layer comparison method and device for deposition combination type control

Abstract

The invention relates to the technical field of reservoir fine description, in particular to a small layer comparison method and device for deposition combination type control. The method comprises the steps that a logging standard layer is determined according to logging data, and a seismic standard layer is determined according to a three-dimensional seismic data body; oil layer group level stratigraphic comparison is completed on the established stratigraphic comparison skeleton profile of the research area by tracking a seismic standard layer and a logging standard layer; completing sandstone group level stratigraphic comparison on a seismic section by tracking a logging standard layer and comparing curve characteristics of the logging standard layer; and small-layer stratigraphic comparison controlled by a river delta deposition combination type is adopted to obtain a small-layer stratigraphic boundary at the well point. The method solves the problems that an existing small layer comparison method is narrow in application range and large in limitation, and particularly for a river-delta phase 2-5 m small layer stratum division process which is large in area, large in well number, thin in stratum and fast in phase change, the division process is difficult and tedious, the comparison precision is low, and the division result is not fine enough.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of reservoir fine description, and particularly relates to a small layer correlation method and device controlled by sedimentary combination type. BACKGROUND

[0002] The research on the distribution characteristics and sedimentary rules of subsurface geological bodies is largely the stratigraphic division and correlation work. The stratigraphic division and correlation work is the most basic and important work, and is also the most difficult and tedious work. It is directly related to the correct or incorrect understanding of the stratigraphic development mode, the distribution of planar microfacies, the distribution of single sand body, the reservoir structure and the like of the research area, and is the bottleneck of controlling the accuracy and reliability of the understanding of subsurface sedimentary bodies. In the fluvial-delta distributary channel sedimentary strata, the sedimentary environment changes greatly laterally, the channel cutting and filling effect is strong, the lithology and thickness of the strata change dramatically, the marker beds are few, and the self-cycle caused by the sedimentation easily covers the different cycles formed by the tectonic and climate effects, so the stratigraphic correlation is very difficult.

[0003] There are many methods for stratigraphic correlation, including chronological stratigraphic correlation, lithologic correlation, lithofacies correlation, paleontological assemblage correlation, heavy mineral assemblage correlation and structural correlation. At present, the main fine stratigraphic correlation methods are: (1) combined logging curve feature correlation method, the main problems of which are: ① the correlation range is small, which can only be applied to the correlation between development wells in close proximity. With the passage of time or distance, the sedimentary environment will inevitably change, and the combined curve features will also change. ② The lateral change of stratigraphic facies is limited. In lateral correlation, the curve is mainly gradual. If there are factors such as faults, denudation, facies change and the like in close proximity, the combined logging curve features will change greatly, which is difficult to grasp and has poor operability. (2) facies-controlled correlation method, the main problems of which are: ① It is suitable for the correlation of sediments that change quickly, such as alluvial fan, subaqueous fan or turbidite fan, or sediments that have directionality, such as prograding layers of delta, zonally distributed fluvial facies and shoreface sandbar. ② Facies mutations caused by faults, unconformities, sedimentary discontinuities and the like can easily cause difficulties in correlation work. ③ It generally requires thick strata and complete data, so that the sedimentary facies can be identified through seismic facies, core facies and logging facies, so as to control the distribution and correlation of microfacies, and to subdivide each stratigraphic unit according to the distribution and mutual relationship of microfacies. (3) cycle correlation method, the main problems of which are: ① It is suitable for areas without denudation or sedimentary discontinuity and with complete cycles. ② It cannot be used to subdivide too finely for sediments that change quickly locally, such as fluvial facies. (4) trend correlation method, the main problems of which are: ① It is only suitable for continuous deposition without tectonic changes in between. ② It is not suitable for areas with strong differential compaction. ③ Large faults can easily disrupt the original trend, causing difficulties in trend correlation. (5) seismic-controlled logging correlation, the main problems of which are: ① It is greatly affected by the quality of seismic data. ② The minimum stratigraphic unit that can be controlled depends on the vertical resolution of seismic data. ③ The seismic data calibration work is large and cumbersome.

[0004] In summary, it is necessary to find a method for fine re-correlation of strata in a study area using seismic data and dense well network data, and to improve the correlation accuracy of 2-5 meter thin strata. SUMMARY

[0005] The present application provides a small layer correlation method and device controlled by sedimentary assemblage type, so as to solve the problems of narrow application range and great limitation of existing small layer correlation methods, especially the difficulty and complexity in the process of dividing 2-5 meter small layer strata of river-delta facies with large area, large number of wells, thin strata and fast facies change, low correlation accuracy and insufficient fineness of division results.

[0006] According to an aspect of the present application, a small layer correlation method controlled by sedimentary assemblage type is provided, comprising:

[0007] obtaining logging data and three-dimensional seismic data volume of a target study area;

[0008] determining a logging standard layer according to the logging data, and determining a seismic standard layer according to the three-dimensional seismic data volume;

[0009] establishing a stratum correlation framework profile of the study area according to the logging data and the three-dimensional seismic data volume, and completing stratum correlation at the oil reservoir group level by tracking the seismic standard layer and the logging standard layer on the framework profile;

[0010] completing stratum correlation at the sandstone group level by tracking the logging standard layer and the correlation logging standard layer curve feature on the seismic profile according to the oil reservoir group level stratum correlation result;

[0011] controlling the small layer level stratum correlation inside the river delta sedimentary assemblage type according to the sandstone group level stratum correlation result, and obtaining the small layer division limit at the well point.

[0012] Preferably, the method for determining a logging standard layer according to the logging data comprises:

[0013] obtaining the thickness of each type of sand body by interpretation using the logging data;

[0014] establishing a logging interpretation column chart using the logging data and the thickness of each type of sand body obtained by interpretation;

[0015] establishing a well-to-well logging interpretation profile using the logging interpretation column chart;

[0016] identifying a logging standard layer using the well-to-well logging interpretation profile.

[0017] Preferably, the method for identifying a logging standard layer using the well-to-well logging interpretation profile comprises:

[0018] performing single logging standard layer correlation, the method of which is: determining a logging standard layer according to the sedimentary characteristics of the correlation interval of a single well, and tracking the logging standard layer to adjacent wells according to its characteristics until the logging standard layer feature is not obvious or disappears completely;

[0019] if the single logging standard layer correlation cannot identify a logging standard layer, performing alternate connection correlation, the method of which is: finding a new logging standard layer in the upper part or lower part adjacent to the existing logging standard layer in a certain area, determining the well at the connection place of the adjacent well group that has the new logging standard layer, and continuously correlating to the surrounding wells to complete logging standard layer identification;

[0020] if the alternate connection correlation cannot identify a logging standard layer, performing combined correlation, the method of which is: performing stratum division correlation and identifying a logging standard layer by using the vertical combination relationship of multiple adjacent logging standard layers according to the vertical multi-layer feature of multiple logging standard layers.

[0021] Preferably, the method for determining seismic standard layers according to the three-dimensional seismic data volume comprises:

[0022] extracting the seismic reflection horizon of the top and bottom and the internal important interface of the oil-bearing formation in the target interval as the seismic standard layer according to the three-dimensional seismic data volume.

[0023] Preferably, before the step of extracting the seismic reflection horizon of the top and bottom and the internal important interface of the oil-bearing formation in the target interval, an important interface is determined by a method comprising:

[0024] determining the reflection coefficient of each interval, and the horizon where the reflection coefficient exceeds a predetermined value is the internal important interface of the oil-bearing formation; wherein the reflection coefficient is calculated by formula (1);

[0025] R = [(v1 x p1) - (v2 x p2)] / [(v1 x p1) + (v2 x p2)] (1);

[0026] wherein v1 is the average velocity of the overlying stratum of the interface, p1 is the average density of the overlying stratum of the interface, v2 is the average velocity of the underlying stratum of the interface, and p2 is the average density of the underlying stratum of the interface.

[0027] Preferably, when the continuity of the same axis, the amplitude reflection, and the waveform feature clarity cannot meet the tracking requirements exist during the step of extracting the seismic reflection horizon of the top and bottom and the internal important interface of the oil-bearing formation in the target interval, then:

[0028] performing well-by-well well array and perpendicular-to-well array direction measuring line interpretation on the seismic profile of the three-dimensional seismic data volume to establish a horizon interpretation skeleton;

[0029] according to the horizon interpretation skeleton, interpreting according to the reflection waveform feature of the same axis at the continuous tracking part of the local same axis, and picking up the maximum wave crest or wave trough of the seismic reflection wave;

[0030] according to the maximum wave crest or wave trough, referring to the top and bottom interpretation horizon, interpreting the horizon according to the principle of equal thickness of strata, and extracting the seismic standard layer.

[0031] Preferably, the method for establishing a stratum correlation skeleton profile of a study area according to the logging data and the three-dimensional seismic data volume comprises:

[0032] determining the acoustic impedance of the well point by using the acoustic travel time and density logging curve in the logging data, and comparing and calibrating the acoustic impedance with the seismic profile to obtain the corresponding relationship between time and depth;

[0033] converting the three-dimensional seismic data volume from the time domain to the depth domain according to the corresponding relationship between time and depth;

[0034] The three-dimensional seismic data body and the well logging data in the depth domain are used to establish a stratum correlation skeleton profile of the study area.

[0035] Preferably, the method further comprises verifying and adjusting the small layer boundary to obtain a final determined small layer horizon.

[0036] The method for verifying and adjusting the small layer boundary to obtain a final determined small layer horizon comprises:

[0037] An interpreted profile of well logging in the study area is obtained.

[0038] The small layer boundary is interpolated according to the seismic standard layer by using a simple Kriging interpolation method to obtain a seismic controlled small layer horizon.

[0039] The small layer boundary is verified and adjusted by using the interpreted profile of well logging and the seismic controlled small layer horizon to obtain a final determined small layer horizon.

[0040] Preferably, before the small layer level stratum correlation controlled by the sedimentary assemblage type is performed, a river delta sedimentary assemblage type is determined, and the method comprises:

[0041] An interpreted profile of well logging in the study area is obtained.

[0042] According to the interpreted profile of well logging, a channel and channel combination, a channel and floodplain combination, a channel and levee combination, and a levee and floodplain combination are determined.

[0043] Preferably, the method for performing the small layer level stratum correlation controlled by the channel and channel combination type to obtain a small layer boundary at a well point comprises:

[0044] According to a sand body cut-and-fold relationship, a small layer boundary at a well point is determined on an interpreted profile of well logging, wherein the sand body cut-and-fold relationship comprises a first type, a second type, and a third type cut-and-fold.

[0045] According to the first type cut-and-fold, a method for determining a small layer boundary at a well point is that if a channel sand body box type or a bell type morphology is complete on a profile in which a later channel undercuts an upper part of an earlier distributary channel, a position of a mudstone at a top and a bottom of a sandstone is a small layer boundary.

[0046] According to the second type cut-and-fold, a method for determining a small layer boundary at a well point is that if a channel sand body box type or a bell type morphology is basically complete on a profile in which a later channel undercuts an earlier channel sand body, a position of a mudstone at a top and a bottom of a sandstone or a maximum position of a curve fluctuation drop is a small layer boundary.

[0047] If the late-stage channel has deeply cut the early-stage channel sand body on the profile, the channel sand body box type and bell type form are completely destroyed, the maximum curve fluctuation and drop or the similar thickness of adjacent wells are used to determine the small layer division limit.

[0048] Preferably, the method for obtaining the small layer division limit at the well point by taking the channel and floodplain combination type control includes:

[0049] On the well-to-well logging interpretation profile, if there is a direct contact between thick channel sandstone and floodplain mudstone, muddy siltstone and silty mudstone, there is a predetermined change in the thickness of the channel boundary sandstone, the top and bottom mudstone reaches a predetermined thickness of the sedimentary combination, and the logging curve characteristics are converted from smooth box type and bell type to smooth near straight line type curve, which is a sudden contact relationship, then the sudden contact point and the maximum curve fluctuation and drop are the small layer division limit.

[0050] Preferably, the method for obtaining the small layer division limit at the well point by taking the channel and floodplain combination type control includes:

[0051] On the well-to-well logging interpretation profile, if there is a direct contact between thick channel sandstone and predetermined quality thin layer, dike sandstone, the logging curve characteristics are converted from smooth box type and bell type to sawtooth bell type, and the sandstone thickness gradually thins; then the sudden contact point, the maximum curve fluctuation and drop, and the similar thickness of adjacent wells are the small layer division limit.

[0052] Preferably, the method for obtaining the small layer division limit at the well point by taking the channel and floodplain combination type control includes:

[0053] On the well-to-well logging interpretation profile, if there is a direct contact between thick channel sandstone and predetermined quality thin layer, dike sandstone, the logging curve characteristics are converted from smooth box type and bell type to sawtooth bell type, and the sandstone thickness gradually thins; then the sudden contact point, the maximum curve fluctuation and drop, and the similar thickness of adjacent wells are the small layer division limit.

[0054] According to an aspect of the present disclosure, a small layer comparison device controlled by a sedimentary combination type is provided, comprising:

[0055] An acquisition unit is configured to acquire well logging data and a three-dimensional seismic data body of a target study area;

[0056] A standard layer determination unit is configured to determine a logging standard layer according to the well logging data, and determine a seismic standard layer according to the three-dimensional seismic data body;

[0057] An oil layer group level comparison unit is configured to establish a stratum comparison framework profile of the study area according to the well logging data and the three-dimensional seismic data body, and complete oil layer group level stratum comparison by tracking the seismic standard layer and the logging standard layer on the framework profile;

[0058] The sandstone group level contrast unit is used for completing the sandstone group level stratum contrast by tracking the logging standard layer and contrasting the logging standard layer curve features on the seismic profile according to the oil layer group level stratum contrast result.

[0059] The sublayer level contrast unit is used for completing the sublayer level stratum contrast controlled by the river delta sedimentary combination type in the sandstone group level stratum contrast result to obtain the sublayer division limit at the well point.

[0060] The present application has at least the following beneficial effects:

[0061] The present application provides a sublayer contrast method and device controlled by the sedimentary combination type, which is matched by using the logging data and the seismic data, and the stratum division method of the oil layer group level stratum is formed by mainly tracking the seismic standard layer, the sandstone group level stratum division method of the logging curve features and the seismic profile reflection features combination, and the sedimentary combination type controlled sedimentary type combination feature sublayer level stratum division method is established, so that the stratum of the research area is finely re-contrasted, the contrast precision of the 2-5m thin stratum is improved, and the important foundation for further improving the reservoir description precision is laid. BRIEF DESCRIPTION OF DRAWINGS

[0062] The drawings incorporated into the specification and forming a part of the specification, show embodiments consistent with the present application, and together with the specification, serve to explain the technical solutions of the present application.

[0063] Figure 1 A flow chart of the sublayer contrast method controlled by the sedimentary combination type according to the embodiment of the present application is shown.

[0064] Figure 2 A seismic standard layer reflection coefficient chart according to the embodiment of the present application is shown.

[0065] Figure 3 A logging standard layer seismic reflection feature profile chart according to the embodiment of the present application is shown.

[0066] Figure 4 A logging standard layer logging curve feature and seismic reflection feature contrast chart according to the embodiment of the present application is shown.

[0067] Figure 5 A sedimentary combination type chart according to the embodiment of the present application is shown.

[0068] Figure 6 A seismic control sublayer horizon sublayer limit checking profile chart according to the embodiment of the present application is shown.

[0069] Figure 7 A fault position checking profile chart according to the embodiment of the present application is shown.

[0070] Figure 8 A small layer level stratigraphic framework system diagram is shown according to an embodiment of the present application. DETAILED DESCRIPTION

[0071] Various exemplary embodiments, features, and aspects of the present application will be described in detail below with reference to the accompanying drawings. The same reference numbers in different drawings denote the same or similar elements. Although various aspects of embodiments are illustrated in the drawings, the drawings are not necessarily drawn to scale unless specifically noted.

[0072] The term "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

[0073] The term "and / or" used herein only means an association relationship of associated objects, and means that there can be three relationships, for example, A and / or B can mean that A exists alone, A and B exist together, and B exists alone. In addition, the term "at least one" herein means any one of a plurality or any combination of at least two of a plurality, for example, at least one of A, B, and C can mean any one or more elements selected from the set consisting of A, B, and C.

[0074] In addition, in order to better illustrate the present application, numerous specific details are given in the following detailed description. Those skilled in the art will understand that the present application can be implemented without certain specific details. In some examples, methods, means, elements and circuits well known to those skilled in the art are not described in detail in order to highlight the main idea of the present application.

[0075] Figure 1 A flow chart of a small layer contrast method according to an embodiment of the present application is shown. Figure 2 A seismic standard layer reflection coefficient map according to an embodiment of the present application is shown. Figure 3 A well logging standard layer seismic reflection feature profile map according to an embodiment of the present application is shown. Figure 4 A well logging standard layer logging curve feature and seismic reflection feature contrast map according to an embodiment of the present application is shown. Figure 5 A sedimentary combination type map according to an embodiment of the present application is shown. Figure 6 A seismic control small layer horizon small layer limit verification profile map according to an embodiment of the present application is shown. Figure 7 A fault position verification profile map according to an embodiment of the present application is shown. Figure 8 A small layer level stratigraphic framework system diagram according to an embodiment of the present application is shown. As Figures 1-8As shown, a small layer contrast method controlled by sedimentary assemblage type is characterized by comprising the following steps: S01, acquiring well logging data and a three-dimensional seismic data volume of a target study area; S02, determining a well logging standard layer according to the well logging data, and determining a seismic standard layer according to the three-dimensional seismic data volume; S03, establishing a stratum contrast skeleton profile of the study area according to the well logging data and the three-dimensional seismic data volume, and completing stratum contrast at the oil group level by tracking the seismic standard layer and the well logging standard layer on the skeleton profile; S04, completing stratum contrast at the sandstone group level by tracking the well logging standard layer and contrast well logging standard layer curve characteristics on a seismic profile according to the stratum contrast result at the oil group level; and S05, obtaining a small layer delimitation at a well point by taking small layer stratum contrast controlled by river delta sedimentary assemblage type inside the sandstone group according to the stratum contrast result at the sandstone group level.

[0076] The small layer contrast method controlled by sedimentary assemblage type provided by the embodiment of the present application specifically comprises the following steps:

[0077] S01, acquiring well logging data and a three-dimensional seismic data volume of a target study area.

[0078] In the embodiment of the present application, drilling and well logging are performed in a target study area of river-delta deposition to obtain well logging data, and seismic acquisition is performed in the target study area to obtain a three-dimensional seismic data volume.

[0079] S02, determining a well logging standard layer according to the well logging data, and determining a seismic standard layer according to the three-dimensional seismic data volume.

[0080] In the present application, the method for determining a well logging standard layer according to the well logging data comprises the following steps: interpreting thicknesses of various types of sand bodies by using the well logging data; establishing a well logging interpretation column chart by using the well logging data and the interpreted thicknesses of various types of sand bodies; establishing a well-to-well well logging interpretation profile by using the well logging interpretation column chart; and identifying a well logging standard layer by using the well-to-well well logging interpretation profile.

[0081] In the embodiment of the present application, thicknesses of various types of sand bodies are interpreted by using the well logging data; a single-well well logging interpretation column chart is established by using spontaneous potential, natural gamma and micro-electrode, micro-potential well logging curves in the well logging data and the interpreted thicknesses of various types of sand bodies; a well-to-well well logging interpretation profile chart of adjacent wells is established by using the single-well well logging interpretation column chart; and a well logging standard layer is identified by using the well-to-well well logging interpretation profile chart.

[0082] In the present application, the method for identifying the logging standard layer by using the well tie logging interpretation profile comprises: single logging standard layer correlation, which is performed according to the sedimentary characteristics of the single well correlation layer section to determine the logging standard layer, and the logging standard layer is tracked to the adjacent well according to its characteristics until the logging standard layer feature is not obvious or disappears completely; if the single logging standard layer correlation cannot identify the logging standard layer, then alternate connection correlation is performed, which is performed by finding a new logging standard layer in the upper or lower part adjacent to the logging standard layer existing in a certain region, determining the well at the connection place of the adjacent well group, and continuously correlating to the surrounding to complete the identification of the logging standard layer; if the alternate connection correlation cannot identify the logging standard layer, then combined correlation is performed, which is performed by using the vertical combination relationship of multiple adjacent logging standard layers to divide and correlate the strata according to the vertical multi-layer characteristics of multiple logging standard layers to identify the logging standard layer.

[0083] In the embodiment of the present application, the logging standard layer refers to a thin layer of sediment having unique electrical characteristics, being obviously different from the upper and lower adjacent strata, being easy to identify and correlate on the plane, and being continuously traceable in a small range (within a few square kilometers or a few tens of square kilometers), the bottom interface of which is an isochronal surface, and is formed by local small range geological action in a very short geological period, and the stability degree is 50% to 90%. In the river-delta depositional system, the overflow deposition, the crevasse splay deposition, the interdistributary lake or depression deposition, the interdistributary special thin layer deposition, the top surface of the wide contemporaneous river channel cycle, and the thin layer sand bottom surface between the underwater distributary channels in the delta front subfacies are all good logging standard layers.

[0084] The specific operation of the correlation method of the logging standard layer comprises the following three levels:

[0085] ① Single logging standard layer correlation: first, the possible logging standard layer is determined based on the understanding of the sedimentary characteristics of the single well correlation layer section, and the logging standard layer is tracked to the adjacent well according to its characteristics until the logging standard layer feature becomes not obvious or disappears completely.

[0086] ② Logging standard layer alternate connection correlation: multiple logging standard layers are often developed in the same set of sedimentary strata, so when a logging standard layer exists in a small area and becomes not obvious or not easy to identify or does not exist in the surrounding, another new logging standard layer exists in the upper or lower part adjacent to the logging standard layer, and the new logging standard layer is obvious and stable in distribution in the adjacent area of the target well. Moreover, the two logging standard layers exist in one or several wells at the connection place of the two adjacent well groups (the target well and the adjacent well), so as to determine the corresponding relationship of the two logging standard layers and play a connection role. Thus, the logging standard layer alternate connection correlation is continuously correlated to the surrounding.

[0087] 3. The combination correlation of the "logging standard layer": Because the curve characteristics and distribution stability of the single "logging standard layer" are not obvious, the vertical combination relationship of the multiple adjacent "logging standard layers" is used to determine the standard layer by the vertical multi-layer characteristics of the multiple "logging standard layers", so that the correlation reliability is improved.

[0088] In the application, the method for determining the seismic standard layer according to the three-dimensional seismic data volume comprises: extracting the seismic reflection horizon of the top and bottom and the internal important interface of the oil reservoir group of the target layer as the seismic standard layer according to the three-dimensional seismic data volume.

[0089] In the embodiment of the application, the seismic marker layer (standard layer) is the seismic reflection horizon of the top and bottom and the internal important interface of the oil reservoir group of the target layer, and the internal important horizon (important interface) refers to the maximum flooding surface, which is stable and widespread and is the most important regional isochronous stratigraphic correlation marker; in the surface outcrop and core profile, the maximum flooding surface is often the top surface of the mudstone section of the upward deepening and thinning sedimentary sequence; on the seismic profile, the reflection interface representing the larger level correlation limit has the high-amplitude continuous reflection characteristics on the seismic reflection profile, and is easy to identify and track.

[0090] In the application, before the extraction of the seismic reflection horizon of the top and bottom and the internal important interface of the oil reservoir group of the target layer, the important interface is determined, and the method comprises: determining the reflection coefficient of each layer, and the horizon with the reflection coefficient exceeding a predetermined value is the internal important interface of the oil reservoir group.

[0091] The reflection coefficient is calculated by using formula (1).

[0092] R = [(v1 x p1) - (v2 x p2)] / [(v1 x p1) + (v2 x p2)] (1).

[0093] In the formula, v1 is the average velocity of the overlying stratum of the interface, p1 is the average density of the overlying stratum of the interface, v2 is the average velocity of the underlying stratum of the interface, and p2 is the average density of the underlying stratum of the interface.

[0094] In the embodiment of the application, the calculation formula of the reflection coefficient is shown in formula (1). The reflection coefficient of each layer is calculated by using formula (1), and the horizon with the high reflection coefficient is the internal important interface of the oil reservoir group.

[0095] For the seismic marker layer with the strong continuity of the phase axis, the obvious amplitude reflection, the stable and clear waveform characteristics and the easy tracking, the horizon automatic tracking technology is mainly used. The automatic tracking can be realized by using the software, and the modification can be performed by the manual intervention in the local unreasonable or unclear places.

[0096] In the present application, when the seismic reflection horizon of the top and bottom and the internal important interface of the oil reservoir group of the extraction target layer section exists the situation that the continuity of the same axis, the amplitude reflection and the waveform feature clarity cannot meet the tracking requirements, then: the seismic profile of the three-dimensional seismic data body is interpreted by over-well well array and the direction perpendicular to the well array direction, the horizon interpretation skeleton is established; according to the horizon interpretation skeleton, the local same axis continuous tracking part is interpreted according to the same axis reflection waveform feature, the maximum wave crest or trough of the seismic reflection wave is picked up; according to the maximum wave crest or trough, the top and bottom interpretation horizon is referred to, the horizon is interpreted according to the stratum equal thickness principle, and the seismic standard layer is extracted.

[0097] In the embodiment of the present application, for the seismic marker layer which is difficult to track locally although the seismic phase axis shows a certain continuity as a whole, such as unclear amplitude reflection and waveform feature, the following method is used for tracking:

[0098] ①Using the advantage of dense well network in the research area, the seismic profile of the three-dimensional seismic data body is interpreted by over-well well array and the direction perpendicular to the well array direction, starting from the geological horizon calibrated by the well point, and the horizon interpretation skeleton is established.

[0099] ②The line direction profile of the interpretation skeleton is closed interpreted: in the local phase axis continuous tracking part, the phase of each same axis is tracked as accurately as possible, and the interpretation line fluctuation amplitude is reduced by strictly interpreting according to the waveform feature of the same axis reflection wave.

[0100] The enlarged monitoring window method is used to accurately pick up the maximum wave crest or trough of the seismic reflection wave, so that the small structure can be effectively interpreted;

[0101] ③When the phase axis is poor and lacks well point control, the horizon is interpreted according to the top and bottom interpretation horizon and the stratum equal thickness principle, and the seismic standard layer is obtained.

[0102] The complete seismic standard layer is obtained by combining the seismic standard layer obtained by automatic tracking with the above-mentioned phase axis continuity which is very strong and the amplitude reflection is obvious.

[0103] Step S03: According to the well logging data and the three-dimensional seismic data body, the stratum correlation skeleton profile of the research area is established, and the oil reservoir group level stratum correlation is completed by tracking the seismic standard layer and the well logging standard layer on the skeleton profile.

[0104] In the present application, the method for establishing a formation correlation framework profile in a study area according to the logging data and a three-dimensional seismic data volume comprises the following steps: determining acoustic impedance at a well point by using acoustic travel time and density logging curves in the logging data, and correlating the acoustic impedance with a seismic profile to obtain a time-depth correspondence; converting the three-dimensional seismic data volume from a time domain to a depth domain according to the time-depth correspondence; and establishing a formation correlation framework profile in the study area by using the three-dimensional seismic data volume in the depth domain and the logging data.

[0105] In the embodiment of the present application, the acoustic impedance at the well point is calculated by using the acoustic travel time curve and the density curve in the logging data, and the acoustic impedance is correlated with the seismic profile to obtain the time-depth correspondence; the time-domain seismic data (three-dimensional seismic data volume) is converted into a depth-domain seismic data volume by using the time-depth correspondence; and the formation correlation framework profile in the study area is established by using the depth-domain three-dimensional seismic volume and the well data (logging data and drilling data).

[0106] On the framework profile, the formation correlation at the oil reservoir group level is completed by tracking the seismic standard layer and the logging standard layer.

[0107] Step S04: According to the formation correlation results at the oil reservoir group level, the formation correlation at the sandstone group level is completed on the seismic profile by tracking the logging standard layer and correlating the curve characteristics of the logging standard layer.

[0108] In the embodiment of the present application, the formation correlation at the sandstone group level is completed by tracking the logging standard layer and correlating the curve characteristics of the logging standard layer according to the waveform characteristics on the seismic profile within each formation at the oil reservoir group level.

[0109] Step S05: According to the formation correlation results at the sandstone group level, the formation correlation at a small layer level controlled by a river delta sedimentary combination type is performed within the sandstone group, and small layer division limits at the well point are obtained.

[0110] In the present application, before the formation correlation at the small layer level controlled by the sedimentary combination type is performed, the river delta sedimentary combination type is determined, and the method comprises the following steps: obtaining a connecting well logging interpretation profile in the study area; and respectively determining the river channel and channel combination, the river channel and floodplain combination, the river channel and bank combination, and the bank and floodplain combination types according to the connecting well logging interpretation profile.

[0111] In the embodiment of the present application, the river-delta sedimentary combination type is established by using the connecting well logging interpretation profile. The formation correlation at the small layer level controlled by the river-delta sedimentary combination type, i.e., the river channel and channel combination, the river channel and floodplain combination, the river channel and bank combination, and the bank and floodplain combination type, is performed within the sandstone group, and small layer division limits at the well point are obtained according to the correlation.

[0112] In the present application, the method for controlling small layer stratigraphic correlation of river channel and river channel combination type, and obtaining small layer stratigraphic boundary at well point, comprises: determining small layer stratigraphic boundary at well point on well-to-well logging interpretation profile according to sand body cut-and-fold relationship, wherein the sand body cut-and-fold relationship comprises three types: type I, type II and type III; wherein, according to the type I cut-and-fold, the method for determining small layer stratigraphic boundary at well point is that, if the upper part of the former distributary channel is cut by the later channel, and the channel sand body is box-shaped or bell-shaped, the position of mudstone at the top and bottom of sandstone is the small layer stratigraphic boundary; wherein, according to the type II cut-and-fold, the method for determining small layer stratigraphic boundary at well point is that, if the later channel cuts the former channel sand body, and the channel sand body is basically box-shaped or bell-shaped, the position of mudstone at the top and bottom of sandstone or the maximum fluctuation of the curve is the small layer stratigraphic boundary; wherein, according to the type III cut-and-fold, the method for determining small layer stratigraphic boundary at well point is that, if the later channel has deeply cut the former channel sand body, and the channel sand body is completely destroyed, the maximum fluctuation of the curve or the thickness of the adjacent well is the small layer stratigraphic boundary.

[0113] In the embodiment of the present application, the river channel-river channel combination is manifested as multi-stage channel cut-and-fold, and the shape change of the channel sand body is closely related to the cut-and-fold relationship of the sand body. The cut-and-fold relationship of the sand body is divided into three types:

[0114] Type I cut-and-fold is that the later channel only cuts the upper part of the former distributary channel, and the lower part of the sand body is completely separable, the channel sand body is box-shaped or bell-shaped, and the position of mudstone at the top and bottom of sandstone is the small layer stratigraphic boundary;

[0115] Type II cut-and-fold is that the later channel cuts the former channel sand body, and the channel sand body is basically separable, the channel sand body is basically box-shaped or bell-shaped, and the position of mudstone at the top and bottom of sandstone or the maximum fluctuation of the corresponding logging curve is the small layer stratigraphic boundary;

[0116] Type III cut-and-fold is that the later channel has deeply cut the former channel sand body, and the channel sand body is completely separable, the channel sand body is completely destroyed, and the maximum fluctuation of the curve or the thickness of the adjacent well is the small layer stratigraphic boundary.

[0117] In the present application, the method for controlling small layer stratigraphic correlation of river channel and river channel combination type, and obtaining small layer stratigraphic boundary at well point, comprises: on well-to-well logging interpretation profile, if there is direct contact between thick channel sandstone and river flood mudstone, muddy siltstone and silty mudstone, the sedimentary combination of the thickness of the channel boundary sandstone has a predetermined change, and the top and bottom mudstone reaches a predetermined thickness, and the logging curve characteristics are converted from smooth box-shaped, bell-shaped to smooth nearly straight line-shaped curve, which is a sudden contact relationship, then the sudden contact point and the maximum fluctuation of the logging curve are the small layer stratigraphic boundary.

[0118] In the embodiment of the present application, the river channel-floodplain combination is manifested as direct contact of thick-layer channel sandstone and floodplain mudstone, argillaceous siltstone and silty mudstone, and the sedimentary combination of large thickness variation of sandstone at the boundary of the channel and large thickness of mudstone at the top and bottom, the corresponding logging curve characteristics are converted from smooth box type and bell type to smooth nearly straight line type curve, the difference is obvious, the boundary is clear, and the contact is abrupt. The stratigraphic correlation mainly follows the principles of equal elevation, equal thickness and equal proportion, and the abrupt contact point and the maximum curve fluctuation and decline are the small layer division boundaries.

[0119] In the present application, the small layer level stratigraphic correlation controlled by the river channel and bank combination type, the method for obtaining the small layer division boundaries at the well point comprises the following steps: on the well-to-well logging interpretation profile, if there is contact between thick-layer channel sandstone and predetermined quality thin layer and bank sandstone, the logging curve characteristics are converted from smooth box type and bell type to sawtooth bell type, and the sandstone thickness gradually thins; the abrupt contact point, the maximum curve fluctuation and decline, and the adjacent well thickness are the small layer division boundaries.

[0120] In the embodiment of the present application, the river channel-bank combination is manifested as contact between thick-layer channel sandstone and thin layer and poor quality bank sandstone, the logging curve characteristics are converted from smooth box type and bell type to sawtooth bell type, and the sandstone thickness gradually thins. When stratigraphic correlation is performed, the relative thickness variation and the curve quality difference are mainly considered, and the abrupt contact point, the maximum curve fluctuation and decline, or the adjacent well thickness are the small layer division boundaries.

[0121] In the present application, the small layer level stratigraphic correlation controlled by the bank and floodplain combination type, the method for obtaining the small layer division boundaries at the well point comprises the following steps: on the well-to-well logging interpretation profile, if there is contact between thin-layer sandstone and mudstone, the rock-electricity characteristics are transitioned from sawtooth bell type to needle type and flat type, and the adjacent well thickness and the equal elevation point are the small layer division boundaries.

[0122] In the embodiment of the present application, the bank-floodplain combination is manifested as contact between thin-layer sandstone and mudstone, the rock-electricity characteristics are transitioned from sawtooth bell type to needle type and flat type, and for river-delta deposition, the adjacent well thickness and the equal elevation point are the small layer division boundaries.

[0123] In the present application, it also comprises checking and adjusting the small layer division boundaries to obtain the finally determined small layer position, wherein the method for checking and adjusting the small layer division boundaries to obtain the finally determined small layer position comprises the following steps: obtaining the well-to-well logging interpretation profile in the study area; using the simple Kriging interpolation method, the small layer division boundaries are interpolated according to the seismic standard layer to obtain the seismic control small layer position; using the well-to-well logging interpretation profile and the seismic control small layer position, the small layer division boundaries are checked and adjusted to obtain the finally determined small layer position.

[0124] In the embodiment of the present application, the well point small layer layer position is obtained by using the well point small layer data obtained in step S05 as the scatter point data, using the adjacent seismic interpretation layer position (seismic standard layer) as the trend control, using the simple Kriging interpolation method to interpolate the well point small layer data, and controlling the interwell according to the seismic trend to obtain the seismic control small layer layer position which can meet the characteristics of the seismic standard layer and the small layer limit. The seismic control small layer layer position is consistent with the well at the well point and meets the trend characteristics of the seismic between wells.

[0125] Finally, the small layer layer limit position at the well point is checked by using the seismic well tie profile (well tie well logging interpretation profile) and the seismic control small layer layer position, and the rationality of the small layer limit position of the fault position is checked, including whether the small layer layer has the layer leakage and missing phenomenon, and the small layer layer position is adjusted according to the waveform on the seismic.

[0126] The rationality check of the small layer limit position of the fault position is to check the well point and the fault position on the seismic well tie profile according to the position and fault distance of the fault reflected by the seismic profile, adjust and modify the well point position and the small layer layer limit position which have contradictions or are not coordinated. Specifically, the peak position on the seismic well tie profile is matched with the top limit of the oil reservoir group; the waveform characteristics and the seismic layer position at the well point of the seismic control small layer layer position are compared with the small layer layer limit position, and the small layer layer limit position is adjusted.

[0127] In the embodiment of the present application, the SII oil reservoir group in the BYDD area of Daqing oil field is taken as an example to illustrate the implementation process of the method of the present application.

[0128] 1. Research background: The SII oil reservoir group in the research area is 20-60m thick, which can be further divided into 5 sandstone groups, and the 5 sandstone groups are further divided into 14 small layers, and the average small layer thickness is 2-5m. The SII oil reservoir group in the research area is gradually entering the tertiary oil recovery stage, and the reservoir description precision requirement is very high, and it is necessary to accurately divide the 2-5m thick small layer; and the previous stratigraphic division results of the region are still in the sparse well pattern stage, so it is urgent to improve the correlation precision of the 2-5m thin stratum, and further improve the reservoir description precision to lay an important foundation.

[0129] 2. The main research contents and process are as follows:

[0130] (1) Oil reservoir group stratigraphic correlation

[0131] The oil reservoir group stratigraphic correlation is mainly based on the identification of the seismic standard layer. The 3D three-component seismic data of the Lama Dian oil field in the research area is 100km 2 , collected in 2006 and processed in 2007; the high-density 3D seismic data of the Saertu oil field is 690km 2 , collected in 2008 and processed in 2009; the old 3D seismic data of the Xingshugang oil field is 1340km 2Acquired in 2000 and processed in 2007. Analysis shows that the processed seismic data has high energy, a high signal-to-noise ratio, and is uniform, with significant lateral waveform variations, accurately reflecting rich subsurface geological information and suitable for seismic standard layer studies. Larger-scale interfaces, such as..., were identified in the seismic profiles. Figure 2 As shown, this includes Sa II, Sa III, and the floodplain Sa II 9. Sa II 9 is a relatively stable mudstone layer in the entire area, with a reflection coefficient of 0.03, similar to that of the oil layer interface. Therefore, this floodplain can be used as a standard seismic layer, exhibiting high-amplitude continuous reflection characteristics on the seismic profile. The seismic reflections of Sa II exhibit very strong continuity of the same phase axis, making it easy to track. Therefore, automatic layer tracking technology is mainly used for it, with manual intervention used to modify areas where there are local inconsistencies. The seismic phase axes of the top surfaces of Sa II 9 and Sa III show a certain degree of overall continuity, but local tracking is difficult. Therefore, we used the following method for tracking them:

[0132] ① Taking advantage of the high density of well network in the study area, starting from the geological strata marked by well points, we first interpret the well rows and the survey lines perpendicular to the well rows to establish a strata interpretation framework, and then perform closure interpretation of the line direction profile.

[0133] ② In areas where local phase axes can be continuously tracked, strive to accurately track each phase and interpret the data strictly according to the characteristics of the reflected waves to reduce the fluctuation amplitude of the interpretation lines. Employ a magnified monitoring window method to accurately capture the maximum peak or trough of the seismic reflected waves, enabling the effective interpretation of minute structures;

[0134] ③ When there is a difference in the phase axis and there is a lack of well point control, the top and bottom interpretation layers should be used as a reference, and the principle of equal formation thickness should be adopted to interpret the layers.

[0135] (2) Stratigraphic correlation of sandstone group

[0136] The correlation of sandstone group-level stratigraphy mainly relies on the identification of well logging standard layers. The main well logging standard layers in the study area are Sa II 4, Sa II 7, and Sa II 13. These marker layers have a limited distribution range and unstable seismic profile reflection characteristics, such as... Figure 3 As shown, profile tracking and comparison are difficult, requiring the combination of well logging standard layer curve characteristics for tracking and identification, such as... Figure 4 As shown. The comparison method includes three levels of specific operations, namely ① comparison of single logging standard layers, ② comparison of alternating logging standard layers, and ③ comparison of combinations of "logging standard layers".

[0137] (3) Establishment of sedimentary assemblage types and comparison of sublayer division

[0138] According to different sedimentary combination types, the geological layering boundaries are checked by using different comparison principles. The river-delta deposition mainly has the following several sedimentary combination types on the profile:

[0139] The first type: river channel-river channel combination, including three kinds of sand body cut-and-fold relations: type I cut-and-fold, as shown in Fig. Figure 5 a; type II cut-and-fold, as shown in Fig. Figure 5 b; and type III cut-and-fold, as shown in Fig. Figure 5 c. The second type: river channel-river floodplain combination, as shown in Fig. Figure 5 d. The third type: river channel-bank combination, as shown in Fig. Figure 5 e. The fourth type: bank-river floodplain combination, as shown in Fig. Figure 5 f.

[0140] (4) Horizon checking and adjustment

[0141] The well point layering data are used as scatter data, the adjacent seismic interpretation horizon is used as trend control, the well point layering data are interpolated by using simple Kriging, and the well-to-well is controlled according to the seismic trend. The seismic control layering horizon of the seismic well-to-well profile is displayed, as shown in Fig. Figure 6 The layering boundaries of the small layer are checked, whether the layering boundaries of the small layer have the layering interpenetration and the missing phenomenon is checked; the rationality of the layering boundaries of the small layer at the fault position is checked, the well breakpoint and the missing horizon are checked according to the position and the fault throw of the fault reflected by the seismic profile, and the well breakpoint position and the layering boundary position of the small layer which have the contradiction or the incoordination are adjusted and modified.

[0142] As shown in Fig. Figure 7 , Fig. a is a seismic profile, and Fig. b is a small layering boundary graph. In the graph, the original interpretation breakpoint depth of B1-5-43 well is 909.8m, the missing horizon is Sa II4 lower-Sa II9, and the fault throw is 15m. It is found by the seismic profile analysis that the original breakpoint position is at the upper part of the fault, which is about 9m away from the fault, and there is a contradiction with the fault position. It is considered after analysis that the well layering is unreasonable and needs to be adjusted. After adjustment, it is considered that the well breakpoint depth is 918.9m, the missing horizon is Sa II8b-Sa II11, and the fault throw is 10.8m.

[0143] (5) Application effect

[0144] The method is applied to more than 20000 wells in the research area, and the stratum division and correlation of the river-delta facies 2-5m small layer are carried out. Compared with the original method, the division accuracy is improved by 8.2%, reaching 93.6%; the small layer level stratum framework system of the research area is established, as shown in Fig. Figure 8 , which guides the fine adjustment of 120 wells, 41 well fracturing, 70 well reperforation, 8 well water plugging are implemented, and the economic benefit of 1353.22 million yuan is obtained, and very good development and application effect is seen.

[0145] It can be understood that the above-mentioned various method embodiments of the present application can be combined with each other to form combined embodiments without deviating from the logical principles. Due to the limited space, the present application will not be described again.

[0146] The execution subject of the small layer correlation method controlled by the deposition combination type can be a small layer correlation device controlled by the deposition combination type, for example, the small layer correlation method controlled by the deposition combination type can be executed by a terminal device or a server or other processing device, wherein the terminal device can be a user equipment (User Equipment, UE), a mobile device, a user terminal, a terminal, a cellular phone, a cordless phone, a personal digital assistant (Personal Digital Assistant, PDA), a handheld device, a computing device, a vehicle-mounted device, a wearable device, etc. In some possible implementation manners, the small layer correlation method controlled by the deposition combination type can be realized by a processor calling computer readable instructions stored in a memory.

[0147] It can be understood by those skilled in the art that the writing order of each step in the above-mentioned method of the specific embodiment does not mean a strict execution order and does not constitute any limitation on the implementation process. The specific execution order of each step should be determined by its function and possible inherent logic.

[0148] In the present application, a small layer correlation device controlled by the deposition combination type is also proposed, comprising: an acquisition unit configured to acquire well logging data and a three-dimensional seismic data volume of a target study area; a standard layer determination unit configured to determine a well logging standard layer according to the well logging data, and determine a seismic standard layer according to the three-dimensional seismic data volume; a reservoir group level correlation unit configured to establish a stratum correlation framework profile of the study area according to the well logging data and the three-dimensional seismic data volume, and complete reservoir group level stratum correlation by tracking the seismic standard layer and the well logging standard layer on the framework profile; a sandstone group level correlation unit configured to complete sandstone group level stratum correlation by tracking the well logging standard layer and correlation well logging standard layer curve characteristics on a seismic profile according to the reservoir group level stratum correlation result; and a small layer level correlation unit configured to complete small layer level stratum correlation controlled by a river delta deposition combination type in the sandstone group according to the sandstone group level stratum correlation result, and obtain a small layer delimitation at a well point.

[0149] In some embodiments, the device provided by the embodiments of the present application has functions or includes modules and units which can be used to execute the methods described in the above method embodiments, and the specific implementation can refer to the description of the above method embodiments. For the sake of brevity, it will not be described here.

[0150] The present application takes the typical dense well pattern block river delta deposition in oil field as an example, utilizes well logging data and seismic data, carries out well seismic data fine matching, forms the oil reservoir group level stratum division method mainly taking seismic standard layer tracking as the main part, the sandstone group level stratum division method taking the combination of logging curve characteristics and seismic section reflection characteristics as the main part; establishes six kinds of sedimentary combination types of river channel-river channel, river channel-river flood, river channel-bank, bank-river flood, etc., forms the sedimentary type combination characteristic sublevel stratum division method matched with the six kinds of sedimentary combination types; utilizes the simple Kriging interpolation to generate the seismic control sublayer position, checks the accuracy of the sublayer limit position and fault breakpoint position, ensures that the sublayer limit division is more fine and reliable. The present application can effectively solve the problems of 2-5m sublayer stratum division difficulty and low comparison precision in river-delta facies, and has great significance for expanding the potential effect of oil field.

[0151] The present application has at least the following beneficial effects: (1) higher division precision: compared with the original method, the division precision is improved by 8.2% to 93.6% by applying the present application method to carry out stratum division and comparison of 2-5m sublayer; (2) stronger professional degree: the sublayer division result is consistent with the geological and sedimentary mode characteristics, and is matched with the seismic reflection characteristics, and has strong professional accuracy.

[0152] The above has described the embodiments of the present application, the above description is exemplary, is not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments. The selection of the terms used herein is intended to best explain the principles, practical application or technical improvement in the market of the embodiments, or to enable other ordinary skilled persons in the art to understand the embodiments disclosed herein.

Claims

1. A method for controlling layer correlation based on sedimentary assemblage type, characterized in that, include: Acquire well logging data and 3D seismic data volumes for the target study area; Based on the well logging data, the standard well logging layers are determined, and based on the three-dimensional seismic data volume, the standard seismic layers are determined. Based on the well logging data and the 3D seismic data volume, a stratigraphic correlation framework profile for the study area is established. On the framework profile, the stratigraphic correlation at the oil formation group level is completed by tracing the seismic standard layer and the well logging standard layer. Based on the stratigraphic correlation results of the oil-bearing group, the stratigraphic correlation of the sandstone group was completed on the seismic profile by tracing the standard logging layers and comparing the curve characteristics of the standard logging layers. Based on the stratigraphic correlation results of the sandstone group, a small-level stratigraphic correlation controlled by the river delta sedimentary assemblage type was adopted to obtain the small-level layer boundaries at the well point.

2. The method for controlling layer correlation based on depositional assemblage type according to claim 1, characterized in that, The method for determining the logging standard layer based on the logging data includes: The thickness of various sand bodies can be determined using the well logging data. Using the well logging data and the interpreted thicknesses of various sand bodies, a well logging interpretation columnar section is established; Using the aforementioned logging interpretation columnar section, a continuous well logging interpretation profile is established; The well logging interpretation profile was used to identify the standard logging layers.

3. The method for controlling layer correlation based on depositional assemblage type according to claim 2, characterized in that, The method for identifying standard logging layers using the well logging interpretation profile includes: The method for conducting single well logging standard layer comparison is as follows: based on the sedimentary characteristics of the comparison interval of a single well, determine the well logging standard layer, and trace it to adjacent wells according to its characteristics until the characteristics of the well logging standard layer are not obvious or completely disappear. If the single logging standard layer comparison cannot identify the logging standard layer, then an alternating connection comparison is performed. The method is as follows: find a new logging standard layer in the upper or lower part of the area adjacent to the existing logging standard layer in a certain region, determine the well where it connects with the adjacent well group, and at the same time have the new logging standard layer, and continuously compare with the surrounding area to complete the identification of the logging standard layer. If the alternating connection comparison cannot identify the well logging standard layer, a combined comparison is performed. The method is as follows: based on the vertical multi-layer characteristics of multiple well logging standard layers, the vertical combination relationship of multiple adjacent well logging standard layers is used to perform stratigraphic division comparison and identify the well logging standard layer.

4. The method for controlling layer correlation based on depositional assemblage type according to claim 1, characterized in that, The method for determining seismic standard layers based on the three-dimensional seismic data volume includes: Based on the three-dimensional seismic data volume, the seismic reflection horizons of the top and bottom of the target segment oil layer group and important internal interfaces are extracted as seismic standard horizons.

5. The method for controlling the depositional assemblage type through layer correlation according to claim 4, characterized in that, Before extracting the seismic reflection horizons of the top, bottom, and important internal interfaces of the target oil reservoir group, the method for determining the important interfaces includes: The reflection coefficient of each layer is determined. Layers with reflection coefficients exceeding a predetermined value are considered important interfaces within the oil reservoir group. The reflection coefficient is calculated using formula (1). R=[(v1×ρ1)-(v2×ρ2)]| / |[(v1×ρ1)+(v2×ρ2)] (1); In the formula: v1 is the average velocity of the overlying strata above the interface, ρ1 is the average density of the overlying strata above the interface, v2 is the average velocity of the underlying strata below the interface, and ρ2 is the average density of the underlying strata below the interface.

6. The method for controlling layer correlation based on depositional assemblage type according to claim 4, characterized in that: When extracting seismic reflection horizons of the top, bottom, and important internal interfaces of the target oil layer group, if there are cases where the continuity of the same axis, amplitude reflection, and waveform characteristic clarity do not meet the tracking requirements, then: Interpretation of seismic profiles of 3D seismic data volumes using well-row and perpendicular seismic lines is performed to establish a layer interpretation framework. Based on the stratigraphic interpretation framework, in the local areas where the same axis can be continuously tracked, the interpretation is based on the characteristics of the reflected waveform along the same axis, and the maximum peak or trough of the seismic reflected wave is picked out. Based on the maximum peak or trough, the top and bottom layers are interpreted, and the layers are interpreted using the principle of equal thickness to extract the seismic standard layer.

7. The method for controlling layer correlation based on depositional assemblage type according to claim 1, characterized in that, The method for establishing a stratigraphic correlation framework profile of the study area based on the well logging data and the 3D seismic data volume includes: Using the sonic transit time and density logging curves in the well logging data, the acoustic impedance at the well point is determined, and it is compared and calibrated with the seismic profile to obtain the time-depth correspondence. Based on the time-depth correspondence, the three-dimensional seismic data volume is converted from the time domain to the depth domain; Using the three-dimensional seismic data volume and well logging data in the depth domain, a stratigraphic correlation framework profile of the study area is established.

8. The method for controlling the depositional assemblage type of layer correlation according to claim 1, characterized in that, Also includes: The sub-layer boundaries are checked and adjusted to obtain the final determined sub-layer position; The method for checking and adjusting the sub-layer boundaries to obtain the final determined sub-layer position includes: Obtain well logging interpretation profiles of the study area; Using the simple Kriging interpolation method, the seismic control sub-layer boundaries are interpolated based on the seismic standard layer to obtain the seismic control sub-layer horizon. Using the well logging interpretation profile and seismic control sub-layer position, the sub-layer boundary is checked and adjusted to obtain the final determined sub-layer position.

9. The method for controlling layer correlation based on sedimentary assemblage type according to any one of claims 1-8, characterized in that, Determining the sedimentary assemblage type of a river delta before conducting small-scale stratigraphic correlation controlled by sedimentary assemblage type within it, the method includes: Obtain well logging interpretation profiles of the study area; Based on the well logging interpretation profile, the types of river channel and river channel combination, river channel and floodplain combination, river channel and embankment combination, and embankment and floodplain combination were determined respectively.

10. The method for controlling the depositional assemblage type of layer correlation according to claim 9, characterized in that, The method for obtaining the sub-layer boundaries at the well point by using small-level stratigraphic correlation controlled by river channels and river combination types includes: Based on the sand body overlapping relationship, the sub-layer boundaries at the well points are determined on the well logging interpretation profile. The sand body overlapping relationship includes Class I, Class II, and Class III overlapping relationships. The method for determining the sublayer boundary at the well point based on the aforementioned type of cutting and stacking is as follows: if the later channel cuts down the upper part of the earlier diversion channel on the cross-section diagram, and the channel sand body has a complete box-shaped or bell-shaped shape, then the mudstone position at the top and bottom of the sandstone is the sublayer boundary. The method for determining the sub-layer boundary at the well point based on the two types of cutting and stacking is as follows: if the later channel cuts down to the earlier channel sand body on the cross section, and the box-shaped and bell-shaped shape of the channel sand body is basically intact, then the mudstone position at the top and bottom of the sandstone or the place where the curve undulation falls to the maximum is the sub-layer boundary. The method for determining the sub-layer boundary at the well point based on the three types of overlapping is as follows: if the later channel on the profile has deeply cut into the earlier channel sand body, and the box-shaped and bell-shaped shape of the channel sand body is completely destroyed, then the point where the curve undulation falls the most or the sub-layer boundary is determined based on the similar thickness of the adjacent wells.

11. The method for controlling layer correlation based on depositional assemblage type according to claim 9, characterized in that, The method for obtaining the sub-layer boundaries at the well point by using small-level stratigraphic correlation controlled by river channel and floodplain combination types includes: On the well logging interpretation profile, if there is a thick layer of channel sandstone in direct contact with river mudstone, silty mudstone and silty mudstone, and a sedimentary combination in which the thickness of the sandstone at the channel boundary has a predetermined change and the top and bottom mudstones reach a predetermined thickness, and the logging curve characteristics change from a smooth box shape and bell shape to a smooth near-linear curve, indicating an abrupt contact relationship, then the abrupt contact point and the place where the logging curve fluctuates and falls the most are the boundaries of the sublayer.

12. The method for controlling the depositional assemblage type through layer correlation according to claim 9, characterized in that, The method for obtaining the sub-layer boundaries at the well point by using small-level stratigraphic correlation controlled by river channel and embankment combination types includes: On the well logging interpretation profile, if there is a thick layer of river sandstone in contact with a predetermined quality thin layer of embankment sandstone, the logging curve characteristics will change from a smooth box shape and bell shape to a sawtooth bell shape, and the sandstone thickness will gradually become thinner. The abrupt contact point, the maximum drop in curve undulation, and the point where the thickness of adjacent wells is similar are the boundaries of the sublayer.

13. The method for controlling the depositional assemblage type through layer correlation according to claim 9, characterized in that, The method for obtaining the sub-layer boundaries at the well point by using the combination of levee and floodplain stratigraphic types for small-level stratigraphic correlation includes: In the well logging interpretation profile, if there is a thin layer of sandstone and mudstone in contact, and the rock electrical characteristics transition from a serrated bell shape to a needle-like and straight shape, then the points with similar thickness in adjacent wells and the points with equal elevations serve as the boundaries of the sublayers.

14. A layer-by-layer contrast apparatus for controlling depositional assemblage type, characterized in that, include: The acquisition unit is used to acquire well logging data and 3D seismic data volumes for the target study area. The standard layer determination unit is used to determine the well logging standard layer based on the well logging data, and to determine the seismic standard layer based on the three-dimensional seismic data volume; The oil-reservoir group-level correlation unit is used to establish a stratigraphic correlation framework profile of the study area based on the well logging data and the three-dimensional seismic data volume. On the framework profile, the stratigraphic correlation at the oil-reservoir group level is completed by tracing the seismic standard layer and the well logging standard layer. The sandstone group-level correlation unit is used to complete the sandstone group-level stratigraphic correlation on the seismic profile by tracking the well logging standard layer and comparing the curve characteristics of the well logging standard layer, based on the oil layer group-level stratigraphic correlation results. Small-level correlation units are used to correlate small-level stratigraphy within the sandstone group based on the results of the sandstone group-level stratigraphy correlation, using the river delta sedimentary assemblage type control, to obtain the small-level stratigraphic boundaries at the well point.

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