River boundary identification method based on geological mode and seismic response characteristics

Abstract

The invention discloses a riverway boundary identification method based on a geological mode and seismic response characteristics, and the method comprises the steps: building a riverway sand body boundary geological model, building a seismic section, seismic attribute characteristics, a geological forward modeling model and a forward modeling result which are matched with the model, and deepening the recognition of the deposition characteristics of different types of sand bodies and the seismic corresponding characteristics; the river channel sand body boundary analysis disclosed by the invention accords with geological mode cognition and is also matched with earthquake corresponding characteristics, so that the identification method disclosed by the invention has a relatively high professional identification degree, the analysis and recognition of the river channel boundary are closer to underground reality, the identification precision of the river channel sand body in a development area can be effectively improved, and the development area is more accurate. And the problems of high multiplicity of solutions and high characterization difficulty of the inter-well sand body are effectively solved.

Description

Technical Field

[0001] This disclosure relates to the field of oilfield reservoir prediction, specifically to fine reservoir description, and particularly to a method for identifying river boundaries based on geological models and seismic response characteristics. Background Technology

[0002] The statements in this section provide only background information in connection with this disclosure and do not constitute prior art.

[0003] Accurate identification of channel sandbody boundaries is crucial for predicting fluvial-deltaic facies reservoirs. According to statistics from drilled wells, the channel sandbody in the fluvial-deltaic facies reservoir in the study area exhibits vertical superposition and overlapping of multiple channels. The width of the channel sandbody varies from a few meters to several kilometers in planar dimensions, and its diverse developmental morphologies, scattered distribution, and difficulty in tracing its boundaries pose significant challenges to the identification of channel sandbody boundaries.

[0004] For channel boundary identification, two common methods are used. One method predicts and delineates channel boundaries based solely on the planar distribution and profile characteristics of channel sand bodies encountered in drilling data. Specifically, it uses drilling and logging data to infer and delineate channel boundaries based on the sedimentary model and well logging profile characteristics of the study area. This method lacks sufficient inter-well discrimination criteria, requires a large amount of manual work to draw channel boundaries, and the discrimination results are greatly affected by human factors. The other method predicts channel sand bodies using drilling and seismic data, through seismic attribute extraction and seismic inversion. However, this process lacks geological model guidance, leading to multiple interpretations in the application of results. Therefore, a channel boundary analysis and identification method that incorporates geological model cognition and seismic response characteristics is needed. That is, a seismic response characteristic analysis method that can reflect the geological characteristics of channel sandstone reservoirs is required to improve the accuracy of fluvial-deltaic facies channel sand body boundary identification.

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

[0006] In view of this, this disclosure provides a method for river channel boundary identification based on geological models and seismic response characteristics, which solves the problems of existing methods lacking geological model guidance in the prediction process of river channel sand bodies, having multiple solutions in the application of results, and having low accuracy in identifying river-deltaic facies river channel sand body boundaries.

[0007] To achieve the above-mentioned objectives, the method for river boundary identification based on geological models and seismic response characteristics includes: Based on the sedimentary pattern of the target work area, establish a geological model of the channel sand body boundary; Establish seismic profiles, amplitude attribute characteristics, and geological forward modeling models that match the geological model of the river channel sand body boundary; Based on the geological forward model, model forward modeling and seismic forward modeling were performed to obtain forward modeling simulation results; By analyzing the seismic profiles, amplitude attribute characteristics, geological forward modeling models, and forward modeling simulation results, the sedimentary characteristics and seismic response characteristics of different types of sand bodies are identified, thus revealing the boundaries of channel sand bodies.

[0008] In this disclosure and possible embodiments, the method for establishing a geological model of the channel sand body boundary includes: Based on the well logging data of the target work area, the thickness and depth of the channel sand body were interpreted to determine the geological strata. Typical wells were selected using the interpreted channel sand body thickness and the spontaneous potential curve, microelectrode curve, and micropotential logging curve from the well logging data. A geological model of the river channel sand body boundary was established using the typical wells described above.

[0009] In this disclosure and possible embodiments, the method for establishing a seismic profile matching the geological model of the channel sand body boundary includes: The well point longitudinal wave impedance curve is obtained by dividing the density curve and the sonic transit time curve in the well logging data. By matching the wave impedance curves of the well points with the P-wave impedance of the seismic data, a correspondence between depth and time is established. Based on the aforementioned correspondence, seismic profile features at typical well points are extracted, and a seismic profile matching the geological model of the river channel sand body boundary is established.

[0010] In this disclosure and possible embodiments, the method for establishing amplitude property characteristics that match the geological model of the channel sand body boundary includes: By analyzing the layer properties along the target layer on the seismic profile of the channel sand body, the variation curve of amplitude properties with seismic traces on the profile is obtained. The variation curve of amplitude properties with seismic traces at typical well points is extracted to obtain amplitude property characteristics that match the geological model of the channel sand body boundary.

[0011] In this disclosure and possible embodiments, the method for establishing a geological forward model that matches the geological model of the channel sand body boundary includes: Using the sonic transit time curve and density curve in the well logging data, the petrophysical parameters of the channel sand body, mudstone and surrounding rock at typical well points are calculated; Using the aforementioned rock physical parameters, a geological forward model matching the geological model of the channel sand body boundary is established.

[0012] In this disclosure and possible embodiments, the method for performing model forward modeling based on the geological forward model includes: The forward modeling results were obtained by applying the ray tracing method and using the Ricker wavelet based on the aforementioned forward model.

[0013] In this disclosure and possible embodiments, the method for performing seismic forward modeling based on the geological forward model includes: Based on the forward modeling results, wellpoint seismic trace wavelets are extracted using seismic data, and seismic forward modeling is performed using the sonic transit time curves and density curves in the well logging data to obtain model-based curve forward modeling results.

[0014] In this disclosure and possible embodiments, the method for extracting wellpoint seismic trace wavelets from seismic data is the Weiner-Levinson method.

[0015] In this disclosure and possible embodiments, the river boundary identification method further includes an optimal matching step based on the forward simulation results, wherein the optimal matching method includes: The model-based curve forward modeling results are used to perform interactive analysis with the seismic profile. The interactive analysis method involves comparing the model-based curve forward modeling results with the seismic profile. By adjusting the rock physics parameters and the frequency and length of the wellpoint seismic trace wavelets in the forward modeling model, the model-based curve forward modeling results and the seismic profile achieve the best match.

[0016] In this disclosure and possible embodiments, the geological model of the river sand body boundary is divided into three combinations: river channel-riverplain, river channel-bank, and river channel-river.

[0017] This disclosure has the following beneficial effects: The method for identifying river channel boundaries based on geological models and seismic response characteristics, as proposed in this invention, establishes a geological model of the river channel sand body boundary and develops matching seismic profiles, seismic attribute characteristic analysis, geological forward modeling, and forward simulation results. This deepens the understanding of the sedimentary characteristics and seismic response characteristics of different types of sand bodies. The analysis of river channel sand body boundaries conforms to geological model cognition and matches seismic response characteristics, exhibiting strong professional identification capabilities. The analysis and understanding of river channel boundaries are closer to the actual underground conditions, effectively improving the identification accuracy of river channel sand bodies in development areas and solving the problems of strong ambiguity and high characterization difficulty of inter-well sand bodies. This is of great significance for expanding the potential of oilfields. Attached Figure Description

[0018] The above and other objects, features, and advantages of this disclosure will become clearer from the following description of embodiments with reference to the accompanying drawings, in which: Figure 1 This is a flowchart of a river boundary identification method based on geological models and seismic response characteristics according to an embodiment of this disclosure; Figure 2 a, 2b, and 2c are geological models of river sand body boundaries in three different application examples; Figure 3 a, 3b, and 3c are the seismic profile characteristics of river sand bodies in three different combinations of application examples; Figure 4 a, 4b, and 4c represent the seismic attribute characteristics of river sand bodies in three different combinations of application examples. Figure 5 a, 5b, and 5c are the three combined geological forward modeling forms of river sand bodies in the application examples; Figure 6 a, 6b, and 6c are the forward modeling results of the three combined forms of the application example, respectively. Figure 7 a, 7b, and 7c are respectively the curve simulation results based on the model for the three combinations of application examples; Figure 8 a, 8b, and 8c represent the boundary positions of the channel sand bodies in the three combined profiles of the application example. Figure 9 a, 9b, and 9c represent the boundary positions of the planar river channel sand bodies in the three combined forms of the application example. Detailed Implementation

[0019] The present disclosure is described below based on embodiments; however, it is worth noting that the present disclosure is not limited to these embodiments. In the detailed description of the present disclosure below, certain specific details are described in detail. However, those skilled in the art will fully understand the present disclosure for the parts not described in detail.

[0020] Furthermore, unless the context explicitly requires it, the words "comprising," "including," and similar terms throughout the specification and claims should be interpreted as including rather than exclusive or exhaustive; that is, meaning "including but not limited to."

[0021] To address the challenges of identifying and predicting the boundaries of river sand bodies, the river boundary identification method disclosed herein is based on the following core technical concept: establishing a geological model of the river sand body boundary, along with matching seismic profiles, seismic attribute characteristics, and a geological forward model. Further forward modeling of the geological model is then performed, along with seismic forward modeling, to obtain model-based forward simulation results. This deepens the understanding of the sedimentary characteristics and seismic responses of different types of sand bodies. Ultimately, based on this deepened understanding of the sedimentary characteristics and seismic responses of different types of sand bodies, the method achieves accurate identification of river sand body boundaries.

[0022] Based on the above technical concept, the embodiments of this disclosure provide corresponding technical solutions, specifically: First, a geological model is established according to the sedimentary pattern of the target work area, and forward modeling is performed under the control of the geological model. Then, well point seismic trace wavelets of seismic data are extracted, and model-based curve forward modeling is performed. Second, the amplitude attribute variation curve with seismic trace is extracted using seismic data to obtain the seismic attribute boundary characteristics of the channel sand body. Finally, the geological model, seismic profile, seismic amplitude attribute, and model-based curve forward modeling results are comprehensively analyzed to determine the boundary of the channel sand body.

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the following detailed description of the river boundary identification method based on geological models and seismic response characteristics is provided using specific embodiments and application examples, combined with some conventional technical means in the field involved in this technical solution.

[0024] Figure 1 This is a flowchart of a river boundary identification method based on geological models and seismic response characteristics according to an embodiment of this disclosure; Figure 1 As shown, the river boundary identification method based on geological models and seismic response characteristics includes the following steps: 1. Drilling and logging are carried out in the target work area of ​​river-delta deposition to obtain logging data, and seismic acquisition is carried out in this target work area to obtain three-dimensional seismic data volume (seismic data).

[0025] 2. Using the above logging data, interpret the sandstone thickness and geological strata of the river sand body in this target work area, and obtain logging curves such as spontaneous potential curve, microelectrode curve, micropotential logging curve, density curve and sonic transit time curve from the above logging data; obtain the seismic strata from the above three-dimensional seismic data volume.

[0026] 3. Using the sandstone thickness, spontaneous potential curve, microelectrode curve, and micropotential logging curve of the channel sand body interpreted in the above steps, select typical wells and establish a boundary geological model of the channel sand body.

[0027] In this field, geological models of river channel sand body boundaries are classified into three combinations: channel-floodplain, channel-bank, and channel-channel. Channel-floodplain assemblage: This is a sedimentary assemblage in which thick channel sandstone is in direct contact with floodplain mudstone, silty mudstone and silty mudstone. The thickness of the sandstone varies greatly at the channel boundary and the thickness of the mudstone at the top and bottom is large. The logging curves change from smooth box-shaped and bell-shaped curves to smooth near-linear curves. The differences are obvious and the boundaries are clear, indicating an abrupt contact relationship.

[0028] River channel-bank combination: This is characterized by the contact between thick river channel sandstone and thin, poor-quality bank sandstone. The logging curves change from smooth box-shaped and bell-shaped to serrated bell-shaped, and the sandstone thickness gradually decreases.

[0029] Channel-channel combination: This is characterized by multiple phases of channel overlap and contact, with the morphological changes of channel sand bodies closely related to their overlap relationship. Well logging curves show a combination of smooth box and bell shapes, with irregular variations in sandstone thickness.

[0030] 4. Using geological and seismic horizons, extract seismic profile features and amplitude attribute features, as detailed below: The P-wave impedance curve of the well point is obtained by dividing the density curve and the sonic transit time curve in the well logging data. The P-wave impedance curve of the well point is then matched with the P-wave impedance of the seismic data volume to establish a depth-time correspondence. Based on this correspondence, the seismic profile characteristics of typical channel sand bodies at the well location are extracted, and the channel sand body outline is drawn. The layer-by-layer properties are analyzed along the target layer on the seismic profile, and the amplitude attribute characteristics of the seismic amplitude with the upper channel sand body are statistically analyzed. The variation curve of amplitude attributes with the seismic trace on the profile is obtained, and the channel-floodplain at the well point is extracted. Figure 2 c) River channel-embankment ( Figure 3 c) River channel - river channel ( Figure 4 c) Curves showing the variation of amplitude properties with seismic traces for the three combined forms.

[0031] Based on the three types of geological models mentioned above, the seismic profile characteristics of channel sand bodies can also be divided into three categories: River channel to river floodplain: The seismic profile reflection characteristics change significantly. The seismic waveform is a complex wave in the sand body of the river channel, and transitions to a single wave towards the mud in the river floodplain on both sides. The change in waveform is the boundary of the river channel.

[0032] River channel-bank: The changes in seismic profile reflection characteristics are not obvious, with only a slight increase in waveform amplitude during the transition from river sand body to boundary.

[0033] River channel to river channel: The changes in seismic profile reflection characteristics are not obvious.

[0034] Correspondingly, the amplitude characteristics of channel sand bodies are also divided into three categories: Channel-floodplain: On the amplitude attribute variation curve of the seismic trace, the seismic amplitude attribute values ​​of the channel sand body and the floodplain mud change significantly, making it easy to identify the channel sand boundary.

[0035] River channel-bank: On the amplitude attribute variation curve with seismic trace, there is a slight abrupt change in amplitude energy at the boundary of the river channel sand body, which can reflect part of the river channel sand boundary.

[0036] Channel-to-channel: On the amplitude attribute variation curve of the seismic channel, the seismic amplitude attribute can only reflect the relative change of the channel thickness, and the boundary identification of a single channel is difficult.

[0037] 5. Using the sonic transit time curve and density curve in the above logging curves, calculate the petrophysical parameters of channel sand bodies, mudstone and surrounding rocks at typical well points, such as velocity and density; using the petrophysical parameters of channel sand bodies, mudstone and surrounding rocks at the above typical well points, establish a forward model of the geological model of the channel sand body boundary. Correspondingly, the forward modeling models of channel sand body geological models are also divided into three categories: River channel-floodplain: The forward model can be simplified to the river channel, floodplain, and surrounding rock, with the river channel sand body having a velocity of 2800 m / s and a density of 2.0 g / cm³. 3 The overflow velocity is 3200 m / s and the density is 2.40 g / cm³. 3 The surrounding rock velocity is 3000 m / s and the density is 2.35 g / cm³. 3 .

[0038] River channel-bank: The forward model can be simplified to the river channel, bank, and surrounding rock, with the river sand body having a velocity of 2800 m / s and a density of 2.0 g / cm³. 3 The embankment velocity is 2900 m / s and the density is 2.2 g / cm³. 3 The surrounding rock velocity is 3000 m / s and the density is 2.35 g / cm³. 3 .

[0039] River channel to river channel: The forward model can be simplified to the river channel and surrounding rock, with the river channel sand body having a velocity of 2800 m / s and a density of 2.0 g / cm³. 3 The surrounding rock velocity is 3000 m / s and the density is 2.35 g / cm³. 3 .

[0040] 6. Using the ray tracing method and the Ricker wavelet, forward modeling was performed to obtain the forward modeling results. Correspondingly, the forward modeling results of the channel sand body forward model are also divided into three categories: River channel – floodplain: The location where the seismic waveform transitions from trough to crest at the river channel boundary is easily identifiable.

[0041] River channel-bank: The weak transition point of the seismic waveform from one trough to another at the river channel boundary is relatively easy to identify, with only slight changes in waveform amplitude.

[0042] River channel to river channel: The seismic waveform changes at the river channel boundary are not obvious and are difficult to identify.

[0043] 7. Based on the model forward modeling results, the Weiner-Levinson method is used to extract the wavelet at the well point, and the sonic transit time curve and density curve in the well point logging data are used to perform seismic forward modeling to obtain the model-based curve forward modeling results. Correspondingly, the model-based forward modeling results of channel sand bodies are also divided into three categories: River channel to river floodplain: The changes in seismic waveform characteristics at the river channel boundary from complex waves to single waves are relatively easy to identify.

[0044] River channel-bank: The amplitude of the seismic waveform at the river channel boundary shows slight changes, which are not obvious and are difficult to identify.

[0045] River channel to river channel: In the forward modeling results, the seismic waveform changes at the river channel boundary are not obvious, but the amplitude of the seismic waveform at the bottom of the river channel boundary changes from strong to weak, and the change characteristics are obvious, which can be used to identify the boundary.

[0046] 8. Interactive analysis is performed using model-based curve forward modeling results and seismic profiles. By adjusting the rock physics parameters in the forward modeling model and the frequency and length of the wavelet used at the well points, the forward modeling results and seismic profiles are optimized to achieve the best match. 9. Using the above geological models, seismic profiles, amplitude attribute characteristics, and model-based forward modeling results, a comprehensive analysis and comparison are conducted to determine the boundary locations of various types of channel sand bodies.

[0047] In this embodiment of the disclosure, the method for determining the boundary locations of various types of river sand bodies through comprehensive analysis and comparison is as follows: River channel – floodplain: River channel boundaries can be determined simply by using geological models and amplitude attribute characteristics.

[0048] River channel-bank: River channel boundaries can be determined using geological models, seismic profiles, and amplitude characteristics.

[0049] River channel to river channel: The river channel boundary needs to be determined by combining geological models, seismic profiles, amplitude attribute characteristics and model-based forward modeling results.

[0050] The following uses the SII oil reservoir group in the BY block of Daqing Oilfield as an example to illustrate the specific implementation process and results of the channel sand body boundary identification method of the present invention: 1. Research Background The low accuracy of inter-well sand body prediction in the BY Block SII oil reservoir group's Class II oil reservoirs fails to meet the requirements for precise delineation of sand body boundaries during tertiary oil recovery. Therefore, the method of this invention is applied to identify the channel sand body boundaries of the inter-well sand bodies in the BY Block SII oil reservoir group's Class II oil reservoirs.

[0051] 2. Implementation Content (1) Based on the BY block depositional model, a geological model of the channel sand body was established. Well logging data and 3D seismic data of the BY block were acquired. The well logging data was used to interpret the thickness and depth of the channel sand body's geological stratigraphy. Spontaneous potential (SP) and microelectrode / micropotential logging curves were obtained from the well logging data. Based on the interpreted channel sand body thickness, SP curves, and microelectrode / micropotential curves, a geological model of the channel sand body boundary was established, specifically divided into the channel-floodplain (…). Figure 2a) River channel-embankment ( Figure 2 b) River channel - river channel ( Figure 2 c) Three combination forms.

[0052] Seismic profile characteristics analysis of river channel sand bodies The wellpoint P-wave impedance curve is obtained by dividing the density curve and sonic transit time curve in the well logging data. The wellpoint P-wave impedance curve is then matched with the P-wave impedance of the seismic data volume to establish a depth-time correlation. Based on this correlation, the river channel-riverplain at the wellpoint is extracted. Figure 3 a) River channel-embankment ( Figure 3 b) River channel - river channel ( Figure 3 c) Seismic profile characteristics of three combined forms.

[0053] Seismic attribute feature extraction of river channel sand bodies Analyzing the layer-by-layer properties along the target layer on the seismic profile yields the amplitude attribute variation curve with the seismic trace on the profile, and extracting the channel-floodway at the well point. Figure 4 a) River channel-embankment ( Figure 4 b) River channel - river channel ( Figure 4 c) Curves showing the variation of amplitude properties with seismic traces for the three combined forms.

[0054] Establishment of forward model for river channel sand bodies Using sonic transit time and density curves from well logging data, velocity and density values ​​of channel sand bodies and surrounding lithology at typical well points were extracted. Based on an established geological model, velocity and density values ​​for different lithologies were given (channel sand body velocity 2800 m / s and density 2.0 g / cm³). 3 The overflow velocity is 3200 m / s and the density is 2.40 g / cm³. 3 The embankment velocity is 2900 m / s and the density is 2.2 g / cm³. 3 The surrounding rock velocity is 3000 m / s and the density is 2.35 g / cm³. 3 ), and establish forward modeling models of geological models for three contact modes at river boundaries ( Figure 5 a, 5b, 5c).

[0055] Forward modeling of channel sand bodies The forward modeling model was simulated using the ray tracing method and the Ricker wavelet, and the forward modeling results were obtained. Figure 6 a, 6b, 6c); Based on the model forward modeling results, the Weiner-Levinson method was used to extract the wavelet at the well point, and seismic forward modeling was performed using the sonic transit time curve and density curve in the well point logging data to obtain the model-based curve forward modeling results (a, 6b, 6c). Figure 7 a, 7b, 7c).

[0056] By comparing the model-based curve forward modeling results with the seismic profile, and by adjusting the velocity and density values ​​of different lithologies in the forward modeling model, as well as the frequency and length of the wavelets used in the two forward modeling results, the model-based curve forward modeling results and the seismic profile are optimized to achieve the best match.

[0057] Comprehensive analysis of channel sandbody boundaries to identify channel sandbody boundaries. For channel-floodplain assemblage: that is, a sedimentary assemblage in which thick channel sand is in direct contact with floodplain mudstone, silty mudstone or silty mudstone, with large variations in sandstone thickness at the channel boundary and large thickness of mudstone at the top and bottom. Figure 2 a); The reflection characteristics on the seismic profile show no significant changes, only slight variations. Figure 3 a); The amplitude attribute variation curve with the seismic trace shows that ( Figure 4 a) Track 1 shows developed alluvial mudstone with an attribute value of 75; Tracks 2 and 3 show a sudden change in seismic attribute value from 50 to -70, indicating the left boundary of the channel; Track 5 has a seismic attribute value of -170, a minimum value, indicating the thickest part of the channel; Tracks 6 and 7 show a sudden change in seismic attribute value from -140 to 50, indicating the existence of a right boundary of the channel between the two tracks; Track 10 shows developed alluvial mudstone with a seismic attribute value of 195. In summary, seismic amplitude attributes can accurately reflect the boundaries of isolated channel sand bodies ( Figure 8 a, 9a).

[0058] For the river channel-bank combination: it is a gradual contact relationship between thick sand layers and thinner, lower-quality sandstone. Figure 2 b); The magnitude of the seismic waveform varies at the boundary of the channel sand body on the seismic profile ( Figure 3 b); On the amplitude attribute variation curve with seismic trace, there is a slight abrupt change in amplitude energy at the boundary of the channel sand body, which can reflect part of the channel sand boundary to a certain extent ( Figure 4 b). The boundaries of channel sand bodies can be determined comprehensively based on geological models, seismic profile characteristics, and seismic attributes. Figure 8 b, 9b).

[0059] For channel-channel assemblages: these are formed by the superposition of channel sand bodies from different phases. Figure 2 c); Due to limitations in seismic resolution, it is difficult to distinguish the boundaries of a single river channel on a seismic profile ( Figure 3 c); On the curve of amplitude attribute variation with seismic trace, seismic amplitude attribute can reflect the relative change of channel thickness, and the boundary identification of a single channel is relatively difficult. Figure 4 c); Forward model ( Figure 7 c) The seismic waveform changes at the bottom of the river channel boundary are obvious and can be used to identify the boundary; it is recommended to combine multiple data to determine the boundary of a single channel in a composite river. Figure 8 c, 9c).

[0060] 3. Application Effect This method was applied to adjust and identify the river channel sand body boundary. Verification and analysis were performed using over 100 post-well tests, comparing the results with the original river channel boundary. Figure 9 (as shown by the dashed lines in a, 9b, and 9c), new boundary ( Figure 9 The compliance rate (shown by the solid lines in a, 9b, and 9c) increased by 5.4% to 91.4%.

[0061] The results of the identification using the method of this invention were applied to the fine characterization of 28 typical reservoir layers in the SII oil formation of the BY block, proving the feasibility of the method, realizing the remaining potential, and guiding the formulation of development measures for different types of sand bodies. A total of 41 wells were fractured, 73 wells were perforated, and 8 wells were shut off, resulting in a cumulative increase in oil production of 90,500 tons, showing very good development and application effects.

[0062] As can be seen from the above embodiments and comparative examples, the channel boundary analysis method based on geological models and seismic response characteristics provided by this invention can deepen the understanding of the sedimentary characteristics and seismic response characteristics of different types of sand bodies by establishing geological models of three types of channel sand body boundaries and establishing matching seismic profiles, seismic attribute characteristic analysis, geological forward modeling models and forward modeling results. This makes the analysis and understanding of channel boundaries closer to the underground reality. Therefore, the identification method of this invention can effectively improve the identification accuracy of channel sand bodies in development blocks, solve the problem of strong ambiguity and high characterization difficulty of inter-well sand bodies, and has great significance for expanding the potential tapping effect of oil fields.

[0063] The embodiments described above are merely illustrative of implementation methods of this disclosure, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent disclosure. It should be noted that those skilled in the art can make various modifications, equivalent substitutions, and improvements without departing from the concept of this disclosure, and these all fall within the protection scope of this disclosure. Therefore, the protection scope of this patent disclosure should be determined by the appended claims.

Claims

1. A method for identifying river channel boundaries based on geological models and seismic response characteristics, characterized in that, include: Based on the sedimentary pattern of the target work area, establish a geological model of the channel sand body boundary; Establish seismic profiles, amplitude attribute characteristics, and geological forward modeling models that match the geological model of the river channel sand body boundary; Based on the geological forward model, model forward modeling and seismic forward modeling were performed to obtain forward modeling simulation results; By analyzing the seismic profiles, amplitude attribute characteristics, geological forward modeling models, and forward modeling simulation results, the sedimentary characteristics and seismic response characteristics of different types of sand bodies are identified, thus identifying the boundaries of channel sand bodies.

2. The method for river boundary identification based on geological models and seismic response characteristics according to claim 1, characterized in that, The method for establishing a geological model of the boundary of a river channel sand body includes: Based on the well logging data of the target work area, the thickness and depth of the channel sand body were interpreted to determine the geological strata. Typical wells were selected using the interpreted channel sand body thickness and the spontaneous potential curve, microelectrode curve, and micropotential logging curve from the well logging data. A geological model of the river channel sand body boundary was established using the typical wells described above.

3. The method for river boundary identification based on geological models and seismic response characteristics according to claim 2, characterized in that, The method for establishing a seismic profile that matches the geological model of the channel sand body boundary includes: The well point longitudinal wave impedance curve is obtained by dividing the density curve and the sonic transit time curve in the well logging data. By matching the wave impedance curves of the well points with the P-wave impedance of the seismic data, a correspondence between depth and time is established. Based on the aforementioned correspondence, seismic profile features at typical well points are extracted, and a seismic profile matching the geological model of the river channel sand body boundary is established.

4. The method for river boundary identification based on geological models and seismic response characteristics according to claim 3, characterized in that, The method for establishing amplitude attribute characteristics that match the geological model of the river channel sand body boundary includes: By analyzing the layer properties along the target layer on the seismic profile of the channel sand body, the variation curve of amplitude properties with seismic traces on the profile is obtained. The variation curve of amplitude properties with seismic traces at typical well points is extracted to obtain amplitude property characteristics that match the geological model of the channel sand body boundary.

5. The method for river boundary identification based on geological models and seismic response characteristics according to any one of claims 1-4, characterized in that, The method for establishing a geological forward model that matches the geological model of the river channel sand body boundary includes: Using the sonic transit time curve and density curve in the well logging data, the petrophysical parameters of the channel sand body, mudstone and surrounding rock at typical well points are calculated; Using the aforementioned rock physical parameters, a geological forward model matching the geological model of the channel sand body boundary is established.

6. The method for river boundary identification based on geological models and seismic response characteristics according to claim 5, characterized in that, The method for performing forward modeling based on the geological forward model includes: The forward modeling results were obtained by applying the ray tracing method and using the Ricker wavelet based on the aforementioned forward model.

7. The method for river boundary identification based on geological models and seismic response characteristics according to claim 6, characterized in that, The method for performing seismic forward modeling based on the geological forward model includes: Based on the forward modeling results, wellpoint seismic trace wavelets are extracted using seismic data, and seismic forward modeling is performed using the sonic transit time curves and density curves in the well logging data to obtain model-based curve forward modeling results.

8. The method for river boundary identification based on geological models and seismic response characteristics according to claim 7, characterized in that: The method used to extract wellpoint seismic trace wavelets from seismic data is the Weiner-Levinson method.

9. The method for river boundary identification based on geological models and seismic response characteristics according to claim 8, characterized in that, It also includes an optimal matching step for the forward simulation results, wherein the optimal matching method includes: The model-based curve forward modeling results are used to perform interactive analysis with the seismic profile. The interactive analysis method involves comparing the model-based curve forward modeling results with the seismic profile. By adjusting the rock physics parameters and the frequency and length of the wellpoint seismic trace wavelets in the forward modeling model, the model-based curve forward modeling results and the seismic profile achieve the best match.

10. The method for river boundary identification based on geological models and seismic response characteristics according to any one of claims 1-4 or 6-8, characterized in that: The geological model of the river sand body boundary is divided into three combinations: river channel-riverplain, river channel-bank, and river channel-river channel.

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