Method for determining a real barrier with a barrier property

Abstract

This application discloses a method for determining a true interlayer with sealing properties. The method includes: dividing the target layer containing the core well into multiple high-order sequences and determining the maximum flooding surface corresponding to each high-order sequence; dividing the sedimentary facies in the core well into high-energy sedimentary facies and low-energy sedimentary facies; determining a theoretical interlayer based on the sedimentary facies types of each maximum flooding surface and the sedimentary facies types on both sides of the sequence interface between each high-order sequence, wherein the sedimentary facies types include high-energy sedimentary facies and low-energy sedimentary facies; determining the theoretical interlayer based on the cement content, the mud content, and the pore throat diameter; obtaining the formation pressure of the target layer and the production logging data of the core well, and determining whether the theoretical interlayer is a true interlayer based on the formation pressure and the production logging data. The technical solution provided by this application can improve the accuracy of determining true interlayers.

Description

Technical Field

[0001] This application belongs to the technical field of reservoir stratigraphic properties research, and in particular relates to a method for identifying real interlayers with sealing properties. Background Technology

[0002] Interlayers are a collective term for both barrier layers and interlayers. Barrier layers control or prevent vertical fluid movement, thus aiding in the delineation of reservoir development layers and stratified oil production. During well production, barrier layers act as natural barriers to prevent interference caused by fluid cross-flow between different reservoir development layers. While interlayers do not completely prevent fluid movement, they significantly influence fluid seepage velocity and seepage efficiency. For example, interlayers can block the rise of bottom water, thus slowing the rate of water cut increase in the well and extending its production life. However, current technologies for detecting barrier layers are incomplete due to their diverse geological origins and complex lithology. Detected barrier layers may still exhibit significant permeability and offer little barrier effect against pressure transmission and fluid flow, while detected non-barrier layers may effectively impede pressure transmission and fluid flow. Therefore, improving the accuracy of identifying true barrier layers is a pressing technical challenge. Summary of the Invention

[0003] The embodiments of this application provide a method for determining a real interlayer with sealing properties, thereby improving the accuracy of determining a real interlayer.

[0004] Other features and advantages of this application will become apparent from the following detailed description, or may be learned in part from practice of this application.

[0005] According to a first aspect of the embodiments of this application, a method for determining a real interlayer with sealing properties is provided, characterized in that the method includes: dividing the target layer where the core well is located into multiple high-level sequences in a core well, and determining the maximum flooding surface corresponding to each high-level sequence, wherein the core well is an oil well for obtaining core samples; dividing each sedimentary facies in the core well into high-energy sedimentary facies and low-energy sedimentary facies; and determining the rock strata of each maximum flooding surface and the sequence interface between each high-level sequence based on the sedimentary facies types of each maximum flooding surface and the sedimentary facies types on both sides of the sequence interface between each high-level sequence. Whether it is a theoretical interlayer, the sedimentary facies include high-energy sedimentary facies and low-energy sedimentary facies; based on the core samples obtained from the core well, obtain the cement content, sedimentary facies type, mud content and pore throat diameter of the strata at the non-maximum flooding surface and non-sequence boundary in the core well, and determine whether the strata at the non-maximum flooding surface and the non-sequence boundary are theoretical interlayers based on the cement content, the mud content and the pore throat diameter; obtain the formation pressure of the target layer and the production logging data of the core well, and determine whether the theoretical interlayer is a real interlayer based on the formation pressure and the production logging data.

[0006] In some embodiments of this application, based on the foregoing scheme, the advanced sequence includes a first-order sequence, a second-order sequence, and a third-order sequence. Dividing the target layer where the core well is located into multiple advanced sequences includes: dividing the target layer into multiple first-order sequences according to the deposition time of the first-order sequence; or, dividing the target layer into multiple second-order sequences according to the deposition time of the second-order sequence; or, dividing the target layer into multiple third-order sequences according to the deposition time of the third-order sequence.

[0007] In some embodiments of this application, based on the foregoing scheme, the step of dividing the various sedimentary phases in the core well into high-energy sedimentary phases and low-energy sedimentary phases includes: obtaining the mud content of each sedimentary phase in the core well; classifying the sedimentary phases with mud content less than a preset mud content as high-energy sedimentary phases, and classifying the sedimentary phases with mud content greater than or equal to the preset mud content as low-energy sedimentary phases.

[0008] In some embodiments of this application, based on the foregoing scheme, determining whether the strata of each maximum flooding surface and the sequence interface between each high-level sequence is a theoretical interlayer based on the sedimentary facies types of each maximum flooding surface and the sedimentary facies types on both sides of the sequence interface between each high-level sequence includes: determining the sedimentary facies type of each maximum flooding surface; if the sedimentary facies type of each maximum flooding surface is a low-energy sedimentary facies, then the strata of each maximum flooding surface is a theoretical interlayer; determining the sedimentary facies types on both sides of each sequence interface; if each sequence interface is a transition surface between high-energy sedimentary facies and low-energy sedimentary facies, then the strata of each sequence interface is a theoretical interlayer.

[0009] In some embodiments of this application, based on the foregoing scheme, determining whether the rock strata of the non-maximum flooding surface and the non-sequence boundary are theoretical interlayers based on the cement content, the mud content, and the pore throat diameter includes: determining the rock strata of the non-maximum flooding surface and the non-sequence boundary corresponding to core samples with cement content greater than or equal to a preset cement content as theoretical interlayers; and determining the rock strata of the non-maximum flooding surface and the non-sequence boundary corresponding to core samples with cement content less than a preset cement content, sedimentary facies of low-energy sedimentary facies, mud content greater than or equal to a preset mud content, and pore throat diameter less than a preset pore throat diameter as theoretical interlayers.

[0010] In some embodiments of this application, based on the foregoing scheme, determining whether the theoretical interlayer is a real interlayer based on the formation pressure and the production logging data includes: determining whether there is a sudden change in formation pressure between the formations above and below the theoretical interlayer; if there is a sudden change in formation pressure, then the theoretical interlayer is a real interlayer; and determining whether there is no oil or gas production in the theoretical interlayer based on the production testing data, and whether there is oil and gas production in all formations surrounding the theoretical interlayer; if there is no oil or gas production in the theoretical interlayer... If the formations surrounding the theoretical interlayer produce oil and gas, then the theoretical interlayer is a real interlayer. Based on the formation pressure and the production test data, it is determined whether the pressure gradient of the formation pressure above and below the theoretical interlayer is normal, and whether the permeability difference between the formations above and below the theoretical interlayer is greater than a preset multiple. If the pressure gradient of the formation pressure above and below the theoretical interlayer is normal, and the permeability difference between the formations above and below the theoretical interlayer is greater than a preset multiple, then the theoretical interlayer is a real interlayer.

[0011] In some embodiments of this application, based on the foregoing scheme, the method further includes: acquiring the gamma logging curve, resistivity logging curve, and sonic transit time logging curve of the cored well; determining the true interlayer; and identifying the curve identification criteria in the gamma logging curve, the resistivity logging curve, and the sonic transit time logging curve, wherein the logging identification criteria include curve jump amplitude, logging value range, and curve toothing degree.

[0012] In some embodiments of this application, based on the foregoing scheme, the method further includes: acquiring gamma ray logging curves, resistivity logging curves, and sonic transit-time logging curves of non-cored wells, wherein the non-cored wells are other oil wells in the target layer besides the cored well; determining the theoretical interlayer in the non-cored well based on the gamma ray logging curves, resistivity logging curves, and sonic transit-time logging curves of the non-cored wells, and the curve identification criteria; and determining whether the theoretical interlayer in the non-cored well is a real interlayer based on the formation pressure of the target layer and the production logging data of the non-cored well.

[0013] In some embodiments of this application, based on the foregoing scheme, the method further includes: acquiring seismic data of the target layer, and determining characteristic seismic data corresponding to the actual interlayer based on the seismic data of the target layer; and determining the distribution of the actual interlayer in the non-oil well area of ​​the target layer based on the characteristic seismic data, wherein the non-oil well area is the area in the target layer excluding core wells and non-core wells.

[0014] In some embodiments of this application, based on the foregoing scheme, the seismic data is the wave impedance of the target layer.

[0015] Based on the technical solution proposed in this application, by dividing the target layer into multiple high-level sequences and determining the maximum flooding surface of each high-level sequence, a systematic framework is provided for the subsequent identification of theoretical interlayers. Simultaneously, the sedimentary facies in the target layer are divided into high-energy and low-energy sedimentary facies, which helps to more accurately determine the sedimentary environment and sedimentary process, providing an important basis for the identification of theoretical interlayers. This improves the accuracy of identifying theoretical interlayers, and consequently, the accuracy of identifying actual interlayers with sealing properties. Furthermore, by comprehensively considering factors such as cement content, clay content, and pore throat diameter, the criteria for identifying theoretical interlayers are further improved, enhancing the accuracy of the identification. Moreover, by verifying the theoretical interlayers using formation pressure of the target layer and production logging data from core wells, a more comprehensive basis is provided for determining whether a theoretical interlayer is a true interlayer, improving the accuracy of identifying true interlayers.

[0016] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. In the drawings:

[0018] Figure 1 A flowchart illustrating a method for determining a real, sealing interlayer in one embodiment of this application is shown.

[0019] Figure 2 This illustration shows a schematic diagram of the distribution of sedimentary facies and high-order sequence in the target layer according to one embodiment of this application;

[0020] Figure 3 A schematic diagram showing the cement content of a core sample in one embodiment of this application is illustrated;

[0021] Figure 4 This paper illustrates a schematic diagram of the porosity and pore throat diameter of a core sample in one embodiment of this application.

[0022] Figure 5 This illustration shows a schematic diagram of the actual interlayer distribution in a coring well according to one embodiment of this application;

[0023] Figure 6 A curve identification standard comparison diagram of the actual interlayer is shown in one embodiment of this application;

[0024] Figure 7 This diagram illustrates the actual interlayer distribution in the target layer according to one embodiment of this application. Detailed Implementation

[0025] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0026] Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a thorough understanding of embodiments of this application. However, those skilled in the art will recognize that the technical solutions of this application can be practiced without one or more of the specific details, or other methods, components, apparatuses, steps, etc., can be employed. In other instances, well-known methods, apparatuses, implementations, or operations are not shown or described in detail to avoid obscuring various aspects of this application.

[0027] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities can be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices.

[0028] The flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be broken down, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0029] It should also be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such uses of these terms can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described.

[0030] To enable those skilled in the art to better understand this application, the actual interlayer proposed in this application will first be briefly described.

[0031] Interlayers are a collective term for both barrier layers and interlayers. Barrier layers control or prevent the vertical movement of fluids, thus aiding in the delineation of reservoir development layers and stratified oil production. During well production, barrier layers act as natural barriers to prevent interference caused by fluid cross-flow between different reservoir development layers. While interlayers cannot completely prevent fluid movement, they significantly influence fluid seepage velocity and seepage effect. For example, interlayers can block the rise of bottom water, thereby slowing the rate of water cut increase in the well and extending its production life. However, in existing technologies, due to the diverse geological origins and complex lithology of barrier layers, detection techniques are not yet perfect. Detected barrier layers may still exhibit significant permeability and lack effective pressure transmission and fluid barrier properties, while detected non-barrier layers may have better pressure transmission and fluid flow barrier performance. Based on this, the inventors of this application propose a method for identifying true barrier layers with sealing properties to improve the accuracy of true barrier layer identification.

[0032] Next, we will combine Figure 1 The method for determining the sealing properties of a real interlayer proposed in this application is described in detail.

[0033] See Figure 1 The flowchart illustrates a method for determining a real, sealing interlayer in one embodiment of this application. This method can be executed by a device with computational processing capabilities, such as... Figure 1 As shown, the method may include at least steps 110 to 150:

[0034] Step 110: In the core well, the target layer where the core well is located is divided into multiple high-order sequences, and the maximum flooding surface corresponding to each high-order sequence is determined. The core well is an oil well for obtaining core samples.

[0035] Step 120: Divide the sedimentary facies in the core well into high-energy sedimentary facies and low-energy sedimentary facies.

[0036] Step 130: Based on the sedimentary facies types of each maximum flooding surface and the sedimentary facies types on both sides of the sequence interface between each high-level sequence, determine whether the strata of each maximum flooding surface and the sequence interface between each high-level sequence are theoretical interlayers. The sedimentary facies types include high-energy sedimentary facies and low-energy sedimentary facies.

[0037] Step 140: Based on the core samples obtained from the core well, obtain the cement content, sedimentary facies type, mud content, and pore throat diameter of the rock strata at the non-maximum flooding surface and non-sequence boundary in the core well, and determine whether the rock strata at the non-maximum flooding surface and the non-sequence boundary are theoretical interlayers based on the cement content, the mud content, and the pore throat diameter.

[0038] Step 150: Obtain the formation pressure of the target layer and the production logging data of the core well, and determine whether the theoretical interlayer is a real interlayer based on the formation pressure and the production logging data.

[0039] In this application, the theoretical interlayer is an interlayer that may have sealing properties as determined by geological theory, and the actual interlayer is an interlayer that has been verified to have sealing properties in practice.

[0040] In this application, please refer to Figure 2 This illustration shows a schematic diagram of the distribution of sedimentary facies and high-order sequence in a target layer according to one embodiment of this application. In a specific embodiment of this application, the sedimentary facies in the target layer may specifically include open shelf, slope foot, foreshore, bioclastic shoal, lagoon, tidal channel, hill shoal, and tidal flat. In some other embodiments, the target layer may also include other sedimentary facies, which are not specifically limited in this application.

[0041] In this application, by dividing the target layer into multiple high-level sequences and determining the maximum flooding surface of each high-level sequence, a systematic framework is provided for the subsequent identification of theoretical interlayers. Simultaneously, the sedimentary facies in the target layer are divided into high-energy and low-energy sedimentary facies, which helps to more accurately determine the sedimentary environment and sedimentary processes, providing important evidence for the identification of theoretical interlayers. This improves the accuracy of theoretical interlayer identification, and consequently, the accuracy of identifying actual interlayers with sealing properties. Furthermore, by comprehensively considering factors such as cement content, clay content, and pore throat diameter, the criteria for identifying theoretical interlayers are further refined, improving the accuracy of the identification. Moreover, by verifying the theoretical interlayers using formation pressure of the target layer and production logging data from core wells, a more comprehensive basis is provided for determining whether a theoretical interlayer is an actual interlayer, which can improve the accuracy of identifying actual interlayers.

[0042] In step 110 above, the higher-level sequence includes a first-level sequence, a second-level sequence, and a third-level sequence. The division of the target layer where the coring well is located into multiple higher-level sequences can be performed according to any one of the following steps 111 to 113:

[0043] Step 111: Divide the target layer into multiple first-order sequences according to the first-order sequence deposition time.

[0044] Step 112: Divide the target layer into multiple second-order sequences according to the second-order sequence deposition time.

[0045] Step 113: Divide the target layer into multiple third-order sequences according to the third-order sequence deposition time.

[0046] In this application, it should be noted that dividing the target layer containing the coring well into multiple higher-level sequences requires that the target layer be divided into sequences of the same level. For details, please refer to [link / reference needed]. Figure 2 The target layer where the core well was located was divided into four third-order sequences according to the deposition time of the third-order sequence, such as... Figure 2 As shown, the four third-level sequences are SQ1, SQ2, SQ3 and SQ4.

[0047] In this application, by dividing the target layer into multiple high-level sequences, a systematic framework can be provided for the identification of subsequent theoretical interlayers, and a basis can be provided for the determination of the maximum flooding surface, thereby improving the accuracy of the judgment of real interlayers with sealing properties to a certain extent.

[0048] In step 120 above, the division of the sedimentary facies in the core well into high-energy sedimentary facies and low-energy sedimentary facies can be specifically performed according to the following steps 121 to 122:

[0049] Step 121: Obtain the mud content of each sedimentary phase in the core well.

[0050] Step 122: The sedimentary phases with a mud content less than the preset mud content are classified as high-energy sedimentary phases, and the sedimentary phases with a mud content greater than or equal to the preset mud content are classified as low-energy sedimentary phases.

[0051] In this application, the preset mortar content can be 60%, but depending on actual needs, the mortar content can also be other values. This application does not impose any further restrictions on this.

[0052] In this application, the mud content of each sedimentary facies can be determined by obtaining core samples of each sedimentary facies from the core well. Depending on actual needs, it can also be obtained by other means, and this application does not make specific limitations on this.

[0053] In this application, reference continues to be made to Figure 2 The foreshore, bioclastic shoals, tidal channels, and hill shoals in the sedimentary facies are high-energy sedimentary facies, while the open shelf, slope foot, lagoon, and tidal flat in the sedimentary facies are low-energy sedimentary facies.

[0054] In this application, the sedimentary facies are divided into two categories, high-energy sedimentary facies and low-energy sedimentary facies, based on the content of the silt. The advantage is that the sediments in the low-energy sedimentary facies have a higher mud content, so the permeability of the sedimentary facies is also lower, making it easier to form sealing interlayers. In this way, the accuracy of judging the true interlayers can be improved.

[0055] In step 130 above, the determination of whether the strata at each maximum flooding surface and the sequence interface between each higher sequence layer are theoretical interlayers based on the sedimentary facies types of each maximum flooding surface and the sedimentary facies types on both sides of each higher sequence layer can be performed according to steps 131 to 132 below:

[0056] Step 131: Determine the sedimentary facies type of each maximum flooding surface. If the sedimentary facies type of each maximum flooding surface is a low-energy sedimentary facies, then the rock strata of each maximum flooding surface are theoretical interlayers.

[0057] Step 132: Determine the sedimentary facies types on both sides of each sequence boundary. If each sequence boundary is a transition surface between high-energy and low-energy sedimentary facies, then the strata at each sequence boundary are theoretical interlayers.

[0058] In this application, the maximum flooding surface is the highest rock layer at sea level in a high-level sequence. At the maximum flooding surface, the sedimentary hydrodynamics are weakest, and the sediments of the corresponding low-energy sedimentary facies have a high mud content and low permeability, making it easy to form sealing interlayers. Therefore, the rock layer corresponding to the low-energy sediments at the maximum flooding surface can be identified as the theoretical interlayer. In this way, determining the theoretical interlayer through geological theory can improve the accuracy of judging the actual interlayer.

[0059] In this application, the sequence interface is the interface between different high-level sequences. At the sequence interface, the permeability of high-energy sedimentary phases is generally higher, while the permeability of low-energy sedimentary phases is generally lower. At the transition surface between the high-energy and low-energy sedimentary phases, there is a large permeability difference, which can lead to a situation where fluids have difficulty flowing due to the large difference in permeability. Therefore, at the transition surface between the high-energy and low-energy sedimentary phases at the sequence interface, a sealing interlayer can also be formed. Thus, the transition surface between the high-energy and low-energy sedimentary phases at the sequence interface can be identified as a theoretical interlayer, thereby further improving the accuracy of identifying actual interlayers.

[0060] In step 140 above, determining whether the rock strata at the non-maximum flooding surface and the non-sequence boundary are theoretical interlayers based on the cement content, the clay content, and the pore throat diameter can be performed according to steps 141 to 142 below:

[0061] Step 141: The rock strata corresponding to the non-maximum flooding surface and the non-sequence boundary of the core sample with a cement content greater than or equal to the preset cement content are identified as theoretical interlayers.

[0062] Step 142: The rock strata corresponding to the non-maximum flooding surface and the non-sequence boundary of the core sample with the cement content less than the preset cement content, the sedimentary facies type being low-energy sedimentary facies, the mud content being greater than or equal to the preset mud content, and the pore throat diameter being less than the preset pore throat diameter are identified as theoretical interlayers.

[0063] In this application, the preset cementitious content can be 85%, the preset clay content can be 75%, and the preset pore throat diameter can be 0.5 μm. Depending on actual needs, the preset cementitious content, the preset clay content, and the preset pore throat diameter can also be other parameter values, and this application does not impose specific limitations on them.

[0064] In this application, the cement content, the mud content, and the pore throat diameter can be specifically obtained through experiments using core samples from the core well.

[0065] In this application, for rock strata that are not at the maximum flood level or at the sequence bedding plane, whether they are theoretical interlayers can be determined first by the cement content. This is because cement is a substance that can block pores in rock strata. When the cement content in the rock strata is too high, most of the pores in the rock strata will be blocked by the cement, resulting in the rock strata losing its fluidity. Specifically, as shown below... Figure 3 As shown, a schematic diagram of the cement content of a core sample in one embodiment of this application is illustrated. Therefore, rock strata with higher cement content will have lower permeability, which is conducive to the formation of sealing interlayers. In this way, by identifying rock strata with higher cement content as theoretical interlayers, the accuracy of judging actual interlayers can be further improved.

[0066] In this application, the cement content in the rock strata is low, but the clay content in some low-energy sedimentary facies is high, and most of the pore throat diameters in the low-energy sedimentary facies are less than 0.5 μm, which also leads to low permeability of the rock strata. Specifically, as shown in the example... Figure 4 The diagram shows the porosity and pore throat diameter of a core sample in one embodiment of this application. Therefore, the rock strata corresponding to the non-maximum flooding surface and the non-sequence boundary of a core sample with a cement content less than a preset cement content, a sedimentary facies of low energy sedimentary facies, a mud content greater than or equal to a preset mud content, and a pore throat diameter less than a preset pore throat diameter can be identified as theoretical interlayers. In this way, the accuracy of judging real interlayers can be effectively improved.

[0067] In step 150 above, determining whether the theoretical interlayer is a real interlayer based on the formation pressure and the production logging data can be performed according to steps 151 to 153 as follows:

[0068] Step 151: Based on the formation pressure, determine whether there is a sudden change in the formation pressure of the upper and lower formations of the theoretical interlayer. If there is a sudden change in the formation pressure, then the theoretical interlayer is a real interlayer.

[0069] Step 152: Based on the production test data, determine whether the theoretical interlayer has no oil and gas production and whether the formations surrounding the theoretical interlayer have oil and gas production. If the theoretical interlayer has no oil and gas production and the formations surrounding the theoretical interlayer have oil and gas production, then the theoretical interlayer is a real interlayer.

[0070] Step 153: Based on the formation pressure and the production test data, determine whether the pressure gradient of the formation pressure above and below the theoretical interlayer is normal, and whether the permeability difference between the formation above and below the theoretical interlayer is greater than a preset multiple. If the pressure gradient of the formation pressure above and below the theoretical interlayer is normal, and the permeability difference between the formation above and below the theoretical interlayer is greater than the preset multiple, then the theoretical interlayer is a real interlayer.

[0071] In this application, the preset multiple can specifically be 10 times. Depending on actual needs, the preset multiple can also be other multiples, and this application does not make specific limitations on this.

[0072] In this application, the formation pressure should, under normal circumstances, gradually increase with increasing formation depth. A sudden change in formation pressure can occur, either by a sudden decrease in formation pressure between the strata above and below the theoretical interlayer as formation depth increases, or by a sudden and significant increase in formation pressure between the strata above and below the theoretical interlayer as formation depth increases. If a sudden change in formation pressure occurs, then the theoretical interlayer is a real interlayer. Determining whether a theoretical interlayer is a real interlayer by observing sudden changes in formation pressure can improve the accuracy of identifying real interlayers.

[0073] In this application, because the permeability and pore throat diameter of the interlayer are relatively small, it generally does not store oil and gas. Based on this, it can be determined from the production test data whether the theoretical interlayer produces no oil and gas, and whether the formations surrounding the theoretical interlayer produce oil and gas. If the theoretical interlayer produces no oil and gas, and the formations surrounding the theoretical interlayer produce oil and gas, it means that the oil and gas layers surrounding the theoretical interlayer cannot seep into it. Therefore, the theoretical interlayer has sealing properties, and the theoretical interlayer can be identified as a real interlayer, further improving the accuracy of the identification of the real interlayer.

[0074] In this application, if the permeability difference between the upper and lower strata of the theoretical interlayer is large, exceeding a preset multiple, fluids will have difficulty permeating each other in strata with excessively large permeability differences. Therefore, if the permeability difference between the upper and lower strata of the theoretical interlayer is large, the theoretical interlayer has sealing properties, and the theoretical interlayer can be identified as a real interlayer, thereby improving the accuracy of the judgment of the real interlayer.

[0075] Please refer to the details. Figure 5 The diagram illustrates the actual interlayer distribution in a cored well according to one embodiment of this application. As can be seen from the diagram, the formation pressure of the strata above and below the theoretical interlayers corresponding to the sequence boundary of SQ1 and SQ2 and the maximum flooding level did not change abruptly. However, the formation pressure of the strata above and below the theoretical interlayer corresponding to the sequence boundary of SQ3 (CRII segment) changed abruptly, and the formation pressure of the strata above and below the theoretical interlayer corresponding to the sequence boundary of SQ4 (CRI segment) also changed abruptly. The cement content in the bioclastic shoal at the top of SQ2 and the hill shoal at the top of SQ4 is greater than the preset cement content. The theoretical interlayers with low-energy sedimentary facies and pore throat diameters less than 0.5 μm in the SQ1 to SQ3 sequences showed no oil and gas production in the theoretical interlayers, while the surrounding formations produced oil and gas. In the top of the SQ2 sequence (mB2 section), the formation pressure of the upper and lower formations of the theoretical interlayers did not change abruptly, but the permeability ratio difference between the upper and lower formations was greater than 10 times. Based on the above analysis, the actual interlayers with sealing properties are mainly located in the lower parts of the CRI, CRII, mB1, and mB2 sections and the lower part of the mC section.

[0076] In the method for determining a real, sealing interlayer proposed in this application, the method can be further performed according to the following steps 210 to 220:

[0077] Step 210: Obtain the gamma logging curve, resistivity logging curve, and sonic transit time logging curve of the core well.

[0078] Step 220: Determine the actual interlayer, and identify the curve identification criteria in the gamma logging curve, the resistivity logging curve, and the sonic transit time logging curve. The logging identification criteria include curve jump amplitude, logging value range, and curve toothing degree.

[0079] In this application, the curve identification criteria for determining the actual interlayer in the gamma logging curve, the resistivity logging curve, and the sonic transit time logging curve are specified. For details, please refer to [reference needed]. Figure 6This document shows a curve identification standard comparison diagram of real interlayers in one embodiment of this application. It can be used to identify theoretical interlayers in other oil wells by using curve identification marks on logging curves. In this way, the scope of judgment of real interlayers can be expanded, thereby improving the accuracy of judgment of real interlayers to a certain extent.

[0080] In the method for determining a real, sealing interlayer proposed in this application, the method can also be performed according to the following steps 230 to 250:

[0081] Step 230: Obtain the gamma logging curve, resistivity logging curve and sonic transit time logging curve of the non-cored well, wherein the non-cored well is any oil well in the target layer other than the cored well.

[0082] Step 240: Based on the gamma logging curve, resistivity logging curve, and sonic transit time logging curve of the non-cored well, and the curve identification criteria, determine the theoretical interlayer in the non-cored well.

[0083] Step 250: Based on the formation pressure of the target layer and the production logging data of the non-cored well, determine whether the theoretical interlayer of the non-cored well is a real interlayer.

[0084] In this application, by acquiring the gamma logging curve, resistivity logging curve, and sonic transit time logging curve of non-cored wells, and based on the curve identification standard corresponding to the actual interlayer, the theoretical interlayer in the non-cored well is determined, and the theoretical interlayer is verified. This provides a data basis for the judgment of the actual interlayer, which can effectively improve the range of judgment of the actual interlayer and improve the accuracy of the judgment of the actual interlayer in non-cored wells.

[0085] In the method for determining a real, sealing interlayer proposed in this application, the method may further include the following steps 260 to 270:

[0086] Step 260: Obtain the seismic data of the target layer, and based on the seismic data of the target layer, determine the characteristic seismic data corresponding to the actual interlayer.

[0087] Step 270: Based on the characteristic seismic data, determine the actual interlayer distribution in the non-oil well area of ​​the target layer, wherein the non-oil well area is the area in the target layer excluding the core wells and non-core wells.

[0088] In this application, the seismic data may specifically be the wave impedance of the target layer, and depending on actual needs, the seismic data may also be other parameters.

[0089] In this application, by acquiring seismic data of the target layer and determining characteristic seismic data corresponding to the actual interlayer based on the seismic data of the target layer, the actual interlayer can be correlated with the seismic data to obtain characteristic seismic data. Therefore, the distribution of actual interlayers in non-oil well areas of the target layer can be determined based on the characteristic seismic data. This further expands the scope of judgment of actual interlayers and improves the accuracy of judgment of actual interlayers in non-oil well areas. Furthermore, the distribution of actual interlayers in the target layer can also be obtained, specifically as follows: Figure 7 The diagram shows the distribution of real interlayers in the target layer in one embodiment of this application. The distribution of real interlayers in the target layer can provide sufficient real interlayer data support for the subsequent development of the reservoir in the target layer, which is beneficial to guiding the development of the reservoir.

[0090] Based on the technical solution proposed in this application, by dividing the target layer into multiple high-level sequences and determining the maximum flooding surface of each high-level sequence, a systematic framework is provided for the subsequent identification of theoretical interlayers. Simultaneously, the sedimentary facies in the target layer are divided into high-energy and low-energy sedimentary facies, which helps to more accurately determine the sedimentary environment and sedimentary process, providing an important basis for the identification of theoretical interlayers. This improves the accuracy of identifying theoretical interlayers, and consequently, the accuracy of identifying actual interlayers with sealing properties. Furthermore, by comprehensively considering factors such as cement content, clay content, and pore throat diameter, the criteria for identifying theoretical interlayers are further improved, enhancing the accuracy of the identification. Moreover, by verifying the theoretical interlayers using formation pressure of the target layer and production logging data from core wells, a more comprehensive basis is provided for determining whether a theoretical interlayer is a true interlayer, improving the accuracy of identifying true interlayers.

[0091] The above description is merely an embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A method for determining a real interlayer with sealing properties, characterized in that, The method includes: In the core well, the target layer where the core well is located is divided into multiple high-level sequences, and the maximum flooding surface corresponding to each high-level sequence is determined. The core well is an oil well for obtaining core samples. The sedimentary facies in the core well were divided into high-energy sedimentary facies and low-energy sedimentary facies. Based on the sedimentary facies types of each maximum flooding surface and the sedimentary facies types on both sides of the sequence interface between each high-level sequence, it is determined whether the strata of each maximum flooding surface and the sequence interface between each high-level sequence are theoretical interlayers. The sedimentary facies types include high-energy sedimentary facies and low-energy sedimentary facies. Based on the core samples obtained from the core well, the cement content, sedimentary facies type, mud content, and pore throat diameter of the rock strata at the non-maximum flooding surface and non-sequence boundary in the core well are obtained. Based on the cement content, mud content, and pore throat diameter, it is determined whether the rock strata at the non-maximum flooding surface and the non-sequence boundary are theoretical interlayers. Obtain the formation pressure of the target layer and the production logging data of the core well, and determine whether the theoretical interlayer is a real interlayer based on the formation pressure and the production logging data.

2. The method according to claim 1, characterized in that, The higher-level sequence includes first-level sequence, second-level sequence, and third-level sequence. The division of the target layer containing the coring well into multiple higher-level sequences includes: The target layer is divided into multiple first-order sequences according to the deposition time of the first-order sequence; or... The target layer is divided into multiple second-order sequences according to the deposition time of the second-order sequences; or... The target layer is divided into multiple third-order sequences according to the deposition time of the third-order sequence.

3. The method according to claim 1, characterized in that, The process of dividing the sedimentary facies in the core well into high-energy sedimentary facies and low-energy sedimentary facies includes: Obtain the mud content of each sedimentary phase in the core well; The sedimentary phases with a mud content less than a preset mud content are classified as high-energy sedimentary phases, and the sedimentary phases with a mud content greater than or equal to a preset mud content are classified as low-energy sedimentary phases.

4. The method according to claim 1, characterized in that, The determination of whether the strata at each maximum floodplain and the sequence boundaries between each higher-order sequence layer are theoretical interlayers, based on the sedimentary facies types at each maximum floodplain and the sedimentary facies types on both sides of the sequence boundaries between each higher-order sequence layer, includes: Determine the sedimentary facies type of each maximum flood surface. If the sedimentary facies type of each maximum flood surface is a low-energy sedimentary facies, then the strata of each maximum flood surface are theoretical interlayers. The sedimentary facies types on both sides of each sequence boundary are determined. If each sequence boundary is a transition surface between high-energy and low-energy sedimentary facies, then the strata at each sequence boundary are theoretical interlayers.

5. The method according to claim 1, characterized in that, The determination of whether the strata at the non-maximum flooding surface and the non-sequence boundary are theoretical interlayers based on the cement content, the clay content, and the pore throat diameter includes: The rock strata corresponding to the non-maximum flooding surface and the non-sequence boundary of the core sample with a cement content greater than or equal to the preset cement content are identified as theoretical interlayers. Core samples with cement content less than a preset cement content, sedimentary facies of low energy, mud content greater than or equal to a preset mud content, and pore throat diameter less than a preset pore throat diameter, corresponding to the non-maximum flooding surface and the non-sequence boundary, are identified as theoretical interlayers.

6. The method according to claim 1, characterized in that, The process of determining whether the theoretical interlayer is a real interlayer based on the formation pressure and the production logging data includes: Based on the formation pressure, it is determined whether there is a sudden change in the formation pressure of the formation above and below the theoretical interlayer. If there is a sudden change in the formation pressure, then the theoretical interlayer is a real interlayer. Based on the production test data, it is determined whether the theoretical interlayer has no oil and gas production, and whether the strata surrounding the theoretical interlayer have oil and gas production. If the theoretical interlayer has no oil and gas production, and the strata surrounding the theoretical interlayer have oil and gas production, then the theoretical interlayer is a real interlayer. Based on the formation pressure and the production test data, it is determined whether the pressure gradient of the formation pressure above and below the theoretical interlayer is normal, and whether the permeability difference between the formation above and below the theoretical interlayer is greater than a preset multiple. If the pressure gradient of the formation pressure above and below the theoretical interlayer is normal, and the permeability difference between the formation above and below the theoretical interlayer is greater than the preset multiple, then the theoretical interlayer is a real interlayer.

7. The method according to claim 1, characterized in that, The method further includes: Obtain the gamma logging curve, resistivity logging curve and sonic transit time logging curve of the core well; The true interlayer is determined by the curve identification criteria in the gamma logging curve, the resistivity logging curve, and the sonic transit time logging curve. The logging identification criteria include curve jump amplitude, logging value range, and curve toothing degree.

8. The method according to claim 7, characterized in that, The method further includes: Obtain gamma logging curves, resistivity logging curves, and sonic transit time logging curves from non-cored wells, wherein the non-cored wells are other oil wells in the target layer besides the cored wells. Based on the gamma logging curve, resistivity logging curve, and sonic transit time logging curve of the non-cored well, and the curve identification criteria, the theoretical interlayer in the non-cored well is determined. Based on the formation pressure of the target layer and the production logging data of the non-cored well, determine whether the theoretical interlayer of the non-cored well is a real interlayer.

9. The method according to claim 8, characterized in that, The method further includes: Seismic data of the target layer is acquired, and based on the seismic data of the target layer, characteristic seismic data corresponding to the actual interlayer is determined; Based on the characteristic seismic data, the actual interlayer distribution in the non-oil well area of ​​the target layer is determined. The non-oil well area is the area in the target layer excluding the core wells and non-core wells.

10. The method according to claim 9, characterized in that, The seismic data is the wave impedance of the target layer.

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