Method for establishing electrical property standard of tight sandstone combined test oil layer

Abstract

The application provides a method for establishing an electrical property standard of a tight sandstone combined test oil layer, and the method comprises the following steps: step 1, collecting oil and gas show data of a test oil layer section; step 2, extracting characteristic values of logging curves of each small layer in the test oil layer section, and using the characteristic values to draw an electrical property standard chart; step 3, making a PICKETT electrical property chart of all small layers with oil and gas shows in the test oil layer section; step 4, determining the lower limit of lithology and oiliness in the block; and step 5, determining whether all data points in the chart can reach the lower limit of physical properties of the oil layer in the block. The method optimizes the original electrical property standard establishment process, and makes the lithology, physical property and oiliness standards in the four-property relationship directly used for guiding the determination of the electrical property standard, the whole method has strong operability, and simultaneously provides a thought for accurately establishing the electrical property standard of the same type of reservoir.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of oil reservoir electrical property standard in reservoir evaluation, in particular to a method for establishing the electrical property standard of tight sandstone combined oil production layer. BACKGROUND

[0002] The determination of oil reservoir electrical property standard in reservoir evaluation is very important for the geological research, geological reserve calculation and oilfield development. The oil reservoir electrical property standard is mainly based on coring, single layer oil testing and logging data, and is based on the research of reservoir lithology-oiliness-physical property-electric property, i.e. the "four property relationship", combined with the understanding of oil reservoir geology and fluid property, to determine the oil production lower limit of reservoir. However, in the shallow lake tight sandstone, the reservoir thickness is thin, the physical property is poor, and the development mode is mainly multi-layer combined production and combined testing. The single layer oil testing data is less, and the oil reservoir standard established by the electrical property data of combined production and combined testing layer has a large error. How to establish a reliable electrical property standard to accurately identify the oil reservoir has become one of the key points and difficulties of the evaluation of this type of reservoir.

[0003] In the research of the electrical property standard of tight sandstone reservoir, according to the past experience, the main process of establishing the oil reservoir electrical property standard is as follows: 1. Combining the coring, logging and oil testing data, drawing the lithology and oiliness histogram to determine the effective thickness lithology and oiliness standard of oil reservoir. 2. Through the effective thickness lithology and oiliness standard, using the positive and reverse cumulative method to determine the effective thickness physical property standard of oil reservoir. 3. Combining the logging data, oil testing and production, and effective thickness physical property standard, selecting the better layer in single layer oil testing and combined testing layer to establish the effective thickness electrical property standard chart of oil reservoir. Through the above method, the electrical property standard of oil reservoir can be determined. However, this method has two disadvantages. One is that the lithology and oiliness in the "four property" is not directly used for the establishment of the electrical property standard, and the electrical property standard is highly dependent on the oil testing data. When the single layer oil testing data is less, the error of the established standard will inevitably occur. The second is that there is no basis for selecting the data for establishing the standard in the multi-layer combined testing layer, and the best layer is often selected according to experience. At this time, a part of the oil reservoir will be missed, resulting in the situation that the effective thickness electrical property standard is high. Therefore, a new method is needed to establish the oil reservoir electrical property standard to improve the accuracy of the electrical property standard of multi-layer combined testing oil layer.

[0004] In the Chinese patent application No. CN201410724999.4, a method for identifying oil layer based on compact reservoir conductive factor experiment is disclosed. The method comprises the following steps: S1, obtaining horizontal cores at different depths of the reservoir; S2, obtaining the porosity and permeability of the horizontal cores, and calculating the quality index; S3, measuring the core resistivity and the resistivity of saturated brine to obtain the formation factor; S4, performing nuclear magnetic resonance measurement to obtain T2 spectrum, total porosity, effective porosity and irreducible water saturation; S5, performing X-ray diffraction and casting thin section experiment; S6, establishing the correlation between the formation factor and the related factors including the total porosity, effective porosity, pore throat size and distribution, and connectivity according to the measurement and experimental results; and S7, determining the oil layer identification algorithm based on the established correlation to identify the oil layer of the reservoir.

[0005] In the Chinese patent application No. CN201910577644.X, a comprehensive identification method for low-porosity, low-permeability and low-resistivity sandstone oil layer is disclosed, which comprises the following steps: step 1, establishing several effective fluid identification charts; step 2, calculating the discrimination coincidence rate of each fluid identification chart; step 3, bringing the logging data of the well to be evaluated into the several fluid identification charts established in step 1, and calculating the fluid identification factor of the horizontal axis and the vertical axis in each chart; step 4, determining the fluid identification result of each depth point, and obtaining the fluid identification curve of each fluid identification chart according to the fluid identification result; and step 5, comprehensively identifying the well to be evaluated.

[0006] In the Chinese patent application No. CN201811595133.2, a method for identifying high salinity and low resistivity oil layer is disclosed, which comprises the following steps: step one, calculating the mud resistivity under the temperature condition of the formation; step two, calculating the ratio of the relative spontaneous potential to the mud resistivity; step three, constructing the apparent resistivity of the oil layer; step four, calculating the ratio of the apparent resistivity of the oil layer to the resistivity of the reservoir; step five, constructing the apparent resistivity of the water layer; step six, calculating the ratio of the apparent resistivity of the water layer to the resistivity of the reservoir; step seven, determining the identification standard of the high salinity and low resistivity oil layer; and step eight, identifying the high salinity and low resistivity oil layer.

[0007] The above prior art has great difference from the present application, and cannot solve the technical problems we want to solve. Therefore, we have invented a new method for establishing the electrical property standard of the combined test oil layer of compact sandstone. SUMMARY

[0008] The purpose of the present application is to provide a method for establishing the electrical property standard of the combined test oil layer of compact sandstone, which formulates a more reasonable establishment process of the electrical property standard of the combined test layer of multiple layers, and solves the technical problems of difficult determination and large error of the electrical property standard of the combined test oil layer of multiple layers.

[0009] The purpose of the present application can be achieved by the following technical measures: the method for establishing the electrical property standard of the tight sandstone combined test oil layer, the method for establishing the electrical property standard of the tight sandstone combined test oil layer comprises:

[0010] Step 1, collecting the logging oil and gas show data in the test oil layer section;

[0011] Step 2, extracting the characteristic values of the logging curve of each small layer in the test oil layer section, for drawing the electrical property standard chart;

[0012] Step 3, making the PICKETT electrical property chart of all small layers with oil and gas show in the test oil layer section;

[0013] Step 4, determining the lower limit of the lithology and oiliness in the block;

[0014] Step 5, determining whether all the data points in the chart can reach the lower limit of the physical property of the oil layer in the block.

[0015] The purpose of the present application can also be achieved by the following technical measures:

[0016] In step 1, the logging oil and gas show data in the test oil layer section is collected, mainly the logging lithology description data, and five types of oil and gas show data including oil saturation, oil immersion, oil spot, oil trace and fluorescence are sorted out.

[0017] In step 1, each small layer in the test oil layer section is corresponded to the logging oil and gas show description, when the small layer only corresponds to one type of logging core description record, the oil and gas show of the small layer is unique.

[0018] In step 1, when the small layer corresponds to multiple logging core description records, the type with the largest thickness ratio is selected as the oil and gas show type of the small layer; it is ensured that each small layer in the combined test layer section has a logging oil and gas show data corresponding thereto.

[0019] In step 2, for the small layers with logging oil and gas show in the test oil layer section, including the small layers with oil and gas show such as oil saturation, oil immersion, oil spot, oil trace and fluorescence; the characteristic values of the logging curves such as acoustic travel time and resistivity corresponding to these small layers are extracted as the basic data for establishing the electrical property standard chart in the next step.

[0020] In step 3, the logging oil and gas show is taken as the classification label to establish the acoustic wave-resistivity, porosity-resistivity and other electrical property charts of different oil content levels.

[0021] In step 4, the lower limit of the output industrial oil flow of different blocks is different, the lower limit of the lithology and oiliness in the block is determined, the lowest lithology and oiliness standard of the output industrial oil flow is determined through the statistical analysis of the lithology, oil content level and production situation of the coring well, and the data points with oil content level lower than the oil output lower limit of the block and some lithology data points with high argillaceous and calcareous content are removed from the chart.

[0022] In step 5, the physical property lower limit of the block is determined first; the physical property lower limit is determined by core analysis data, and the effective sample and the ineffective sample in the core are respectively subjected to positive and inverse accumulation, and the intersection value is taken as the physical property lower limit of the block; then the determined physical property lower limit is put into the established electrical property standard chart, and the data point reaching the physical property lower limit is the data finally determining the electrical property standard of the oil layer.

[0023] The method for establishing the electrical property standard of the combined tight sandstone oil testing layer in the application relates to the establishment process of the electrical property standard of the combined tight sandstone multi-layer oil testing layer and the application of the oil-bearing occurrence in mud logging in the establishment of the electrical property standard, and combines the oil-bearing occurrence in mud logging with the oil testing data to select the layer with oil and gas display in the combined multi-layer testing layer to participate in the establishment of the effective thickness electrical property standard, solves the problem that the electrical property standard is difficult to establish due to the lack of single-layer oil testing data, optimizes the original electrical property standard establishment process, and makes the lithology, physical property and oil-bearing property standards in the four-property relationship directly used for guiding the determination of the electrical property standard, so that the whole method has strong operability and provides a thought for accurately establishing the electrical property standard of the same type of reservoir. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 It is a process comparison chart before and after the establishment method of the oil layer electrical property standard is improved;

[0025] Figure 2 It is an electrical property chart based on the oil-bearing occurrence in a specific embodiment 1 of the application;

[0026] Figure 3 It is an oil-bearing occurrence electrical property standard chart before and after the oil-bearing property standard guidance in a specific embodiment 1 of the application;

[0027] Figure 4 It is an oil-bearing occurrence electrical property standard chart before and after the lithology standard guidance in a specific embodiment 1 of the application;

[0028] Figure 5 It is an oil-bearing occurrence electrical property standard chart before and after the physical property standard guidance in a specific embodiment 1 of the application.

[0029] Figure 6 It is an electrical property chart based on the oil-bearing occurrence in a specific embodiment 2 of the application;

[0030] Figure 7 It is an electrical property chart before and after the removal of the influence of the thin layer in a specific embodiment 2 of the application;

[0031] Figure 8 It is an oil-bearing occurrence electrical property standard chart before and after the guidance of the lithology, oil-bearing property and physical property standards in a specific embodiment 2 of the application;

[0032] Figure 9The oil-bearing occurrence-based electrical profile in a specific embodiment 3 of the present application;

[0033] Figure 10 The oil-bearing occurrence-based electrical profile in a specific embodiment 3 of the present application;

[0034] Figure 11 The oil-bearing occurrence-based electrical profile in a specific embodiment 3 of the present application;

[0035] Figure 12 The flow chart of a specific embodiment of the method for establishing the electrical standard of the tight sand combined testing and oil production layer. DETAILED DESCRIPTION

[0036] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0037] It should be noted that the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise, and it should also be understood that when the terms "comprise" and / or "include" are used in the specification, there is a reference to the presence of a feature, step, operation, and / or combinations thereof.

[0038] As shown in Figure 12 The method for establishing the electrical standard of the tight sand combined testing and oil production layer according to the present application establishes the oil-bearing occurrence-based electrical standard through five steps.

[0039] Step 101, collecting oil and gas show data in the testing and oil production layer section, mainly based on lithology description data, and sorting out five types of oil and gas show data including oil saturation, oil immersion, oil stain, oil trace, and fluorescence. Then, each sublayer in the testing and oil production layer section is corresponded to the oil and gas show description, and when the sublayer only corresponds to one type of core description record, the oil and gas show of the sublayer is unique. When the sublayer corresponds to multiple core description records, the type with the largest thickness ratio is selected as the oil and gas show type of the sublayer. It is ensured that each sublayer in the combined testing layer section has an oil and gas show data corresponding thereto.

[0040] Step 102, extracting characteristic values of the logging curves of each sublayer in the testing and oil production layer section for drawing the electrical standard profile. It is mainly for the sublayers with oil and gas show in the testing and oil production layer section, including the sublayers with oil and gas show such as oil saturation, oil immersion, oil stain, oil trace, and fluorescence. The characteristic values of the acoustic travel time and resistivity logging curves of these sublayers are extracted as the basic data for establishing the electrical standard profile in the next step.

[0041] Step 103, make PICKETT electrical chart of all small layers of oil and gas showing oil layer, in the conventional electrical chart, generally different fluids such as oil, gas, water are used as classification labels, and acoustic resistivity, porosity-resistivity electrical chart is established to determine the lower limit value of oil and water layer or oil dry layer. But due to the great uncertainty of fluid properties in the test layer, here the oil and gas show of logging is mainly used as classification label to establish acoustic resistivity, porosity-resistivity electrical chart of different oil content levels.

[0042] Step 104, not every small layer can reach the standard of oil layer in the chart obtained by the above process, and there are some small layers with poor lithology and low oil and gas show level that do not reach the standard of industrial oil flow output, these layers cannot be used to determine the oil layer standard, and the lower limit of industrial oil flow output exists differently for different blocks. At this time, the lower limit of lithology and oil content in the block needs to be determined first, and the lowest lithology and oil content standard of industrial oil flow output is generally determined by statistical analysis of coring well lithology, oil content level and production situation, for example, the lithology of small layers of industrial oil flow output in the block is: oil-soaked fine sandstone, oil spot medium sandstone, oil spot fine sandstone and several other types, and it can be determined that the lower limit of oil output in the block is oil spot fine sandstone, so the data points with oil content level lower than oil spot and some lithology data points with high mud content and ash content are removed from the chart.

[0043] Step 105, finally determine whether all data points in the chart can reach the lower limit of the physical property of the oil layer in the block. Since the electrical chart established based on the oil content of the logging appearance as the basis data cannot directly reflect the good and bad of the physical property of the reservoir, part of the data points in the chart cannot output oil, and these dry layers may also meet the lowest standard of lithology and oil content in the fourth step, but due to the poor physical property, the probability of oil output of these layers is very small, therefore, the physical property is also a necessary condition for determining whether a layer can output oil, so the lower limit of the physical property of the block needs to be determined first. The lower limit of the physical property can be determined by core analysis data, and the effective sample and invalid sample in the core are respectively made positive and inverse cumulative, and the intersection point value can be used as the lower limit of the physical property of the block. Then the determined lower limit of the physical property is put into the established electrical standard chart, and the data points that can reach the lower limit of the physical property are the final data for determining the electrical standard of the oil layer.

[0044] The following are several specific embodiments of the application.

[0045] Example 1:

[0046] Figure 1In the new process, the oiliness, lithology and physical property standards are determined according to the previous working method. The electrical property standard is first established based on the basic data of oil-bearing occurrence, and then verified by the other three standards in turn, and the unreasonable data is gradually removed to obtain the final electrical property standard chart.

[0047] The specific steps are as follows:

[0048] Figure 2 In the new process, the data of the small layer with oil and gas show in the oil testing interval are extracted, including the information of the small layer thickness, acoustic time difference, induced resistivity, lithology, oiliness, etc., as the basic data for establishing the electrical property standard, and the PICKETT electrical property standard chart is made.

[0049] Table 1: Statistical table of electrical property and oil-bearing grade of the combined test interval of beam 206 well

[0050]

[0051] Figure 3 In the new process, after the block determines the oiliness standard as oil spot, the standard is used to guide the PICKETT electrical property standard chart, and the oil trace and fluorescence data in the chart that do not reach the oil spot grade are removed.

[0052] Figure 4 In the new process, after the block determines the lithology standard as gray siltstone, the standard is used to guide the PICKETT electrical property standard chart, and the data in the chart that do not reach the minimum lithology standard such as argillaceous siltstone, gray mudstone and marl are removed.

[0053] Figure 5 In the new process, after the block determines the physical property standard as porosity of more than 10%, the standard is used to guide the PICKETT electrical property standard chart, and the minimum porosity lower limit of the oil layer is 10%, and the final electrical property standard of the block is determined by analyzing the low-yield layer and low-oil-saturation layer in combination with the actual production data.

[0054] Example 2:

[0055] In the specific example 2 of the application, first, the new process of Figure 1 the basic data table based on oil-bearing occurrence is established, as shown in Table 2. In the process of arranging the data table, it is found that there are some thin layers with thickness less than 0.5 in the basic data. The thinner layer cannot reach the longitudinal resolution of the logging curve, so that there is a certain error in the value of the logging curve characteristic value of the thin layer, which will cause error in the established electrical property standard. Therefore, when establishing the PICKETT electrical property standard chart, these thin layers are first removed, and then the three standards of lithology, oiliness and physical property are used in turn for verification to obtain the final electrical property standard.

[0056] The specific steps are as follows:

[0057] Figure 6 In the method, the data of the small layer with oil and gas show in the test oil layer section are extracted, including the layer thickness, acoustic time difference, induced resistivity, lithology, oiliness and other information, as the basic data for establishing the electrical property standard, and the PICKETT electrical property standard chart is made.

[0058] Table 2: Statistics of electrical property and oil content level of the combined test layer section of Bin 444 well

[0059]

[0060] Figure 7 In the method, the well logging series and the thin layer logging response characteristics of the block are analyzed, it is considered that when the layer thickness is less than 0.5 meters, the well logging curve cannot reflect the real value of the reservoir, and this part of the thin layer may cause error in the final standard, therefore, the thin layer with the thickness less than 0.5 meters is removed from the chart first.

[0061] Figure 8 In the method, the lithology and oiliness standards of the block are determined as oil spot siltstone, and the physical property standard is determined as the porosity of more than 12%, the data not reaching the minimum lithology and oiliness standards are removed in turn according to the process, and the PICKETT electrical property standard chart is guided by the physical property standard, and the final electrical property standard of the block is determined in combination with the actual production.

[0062] Example 3

[0063] In the specific example 3 of the application, the basic process is the same as that of example 1, first, the basic data based on the oil content appearance are established, the electrical property chart is drawn, and then the other three standards are used for verification in turn, the unreasonable data are removed gradually, and the final electrical property standard chart is obtained. The difference is that the PICKETT electrical property standard chart is not established here, but the acoustic- induced resistivity crossplot of the block is established. At this time, the standard for verifying the lower limit of the physical property is not the lower limit value of the porosity, but the value of the corresponding acoustic time difference needs to be converted.

[0064] The specific steps are as follows:

[0065] Figure 9 In the method, the data of the small layer with oil and gas show in the test oil layer section are extracted, including the layer thickness, acoustic time difference, induced resistivity, lithology, oiliness and other information, as the basic data for establishing the electrical property standard, and the PICKETT electrical property standard chart is made.

[0066] Figure 10 In the method, the lithology standard of the block is determined as fine sandstone after the oiliness standard is determined as oil trace, and the acoustic- induced resistivity crossplot is guided by the standard, the fluorescence data not reaching the oil trace level in the chart and the data not reaching the minimum lithology standard such as siltstone and argillaceous siltstone are removed.

[0067] Figure 11In the example, the physical property criterion determined by the block is 9.5% of porosity, and the correlation between the porosity of the core experiment of the block and the acoustic travel time is:

[0068] Φ=0.4712△t-21.978

[0069] Φ=0.4712△t-21.978

[0070] △t=the acoustic travel time of the target layer, μs / ft

[0071] The lower limit value of the acoustic travel time of the block is inversely deduced by using the above correlation as 220 μs / m. The physical property criterion is used to guide the acoustic-induction resistivity chart, and the final electrical property criterion of the block is determined in combination with the production practice.

[0072] Finally, it should be noted that the above description is only a preferred embodiment of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments or equivalently replace some of the technical features. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

[0073] In addition to the technical features described in the specification, they are known to those skilled in the art.

Claims

1. A method for establishing electrical criteria for testing compacted sandstone combined production zones, characterized in that, The method for establishing the electrical property standard of the tight sandstone combined test oil layer comprises: Step 1, collecting the oil and gas show data of the test oil layer section; Step 2, extracting the characteristic values of the logging curves of each small layer in the test oil layer section, for drawing the electrical property standard chart; Step 3, making the PICKETT electrical property chart of all small layers with oil and gas show in the test oil layer section; Step 4, determining the lower limit of the lithology and oiliness in the block; Step 5, determining whether all the data points in the chart can reach the physical property lower limit of the oil layer in the block; In step 5, the physical property lower limit of the block is determined first; the physical property lower limit is determined by core analysis data, and the effective sample and the invalid sample in the core are respectively made positive and inverse cumulative, and the intersection value is taken as the physical property lower limit of the block; then the determined physical property lower limit is put into the established electrical property standard chart, and the data points that can reach the physical property lower limit are the final data for determining the electrical property standard of the oil layer.

2. The method for establishing the electrical property standard of the tight sandstone combined production layer according to claim 1, characterized in that, In step 1, each small layer in the test oil layer section corresponds to the oil and gas show description of the logging, and when the small layer corresponds to only one type of logging core description record, the oil and gas show of the small layer is unique.

3. The method for establishing the electrical property standard of the tight sandstone combined production layer according to claim 2, characterized in that, In step 1, when the small layer corresponds to multiple logging core description records, the type with the largest thickness ratio is selected as the oil and gas show type of the small layer; it is ensured that each small layer in the combined test layer section has an oil and gas show data corresponding thereto.

4. The method of establishing electrical standards for tight sand reservoirs of claim 1, wherein, In step 2, for the small layer with oil and gas show in the test oil layer section, the oil and gas show is saturated with oil, oil immersion, oil spot, oil trace and fluorescence; the characteristic values of the acoustic travel time and resistivity logging curves corresponding to the small layer are extracted as the basic data for establishing the electrical property standard chart in the next step.

5. The method of establishing electrical standards for tight sand reservoirs of claim 1, wherein, In step 3, the oil and gas show of the logging is taken as the classification label to establish the acoustic resistivity and porosity resistivity electrical property charts of different oil content levels.

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