A method for determining the original oil-water interface of a block-shaped bottom water buried hill reservoir

Abstract

The present application relates to a kind of block bottom water buried hill reservoir original oil-water interface determination method, belong to the technical field of reservoir development.In single stratum trap, the favorable position of structure is selected to implement test production well, and the preliminary original oil-water interface h i Of stratum trap is obtained by geological information, then the test production well is carried out test production by selecting perforation horizon, when the comprehensive water content of test production well evaluation period is not more than 10%, preliminary original oil-water interface h i Equal to final original oil-water interface h u When the comprehensive water content of test production well evaluation period is more than 10%, preliminary original oil-water interface is reviewed and corrected, so that final original oil-water interface is accurately calculated.The present application comprehensively considers the trap type and storage and seepage characteristics of block bottom water buried hill reservoir, and accurately calculates the original oil-water interface of block bottom water buried hill reservoir with layered structure by using multiple technical means such as comprehensive geochemical logging, well logging, gas logging, test production evaluation, etc., to provide basis for reserve evaluation and development deployment.

Description

Technical Field

[0001] This invention relates to a method for determining the original oil-water interface in a blocky bottom-water buried hill reservoir, belonging to the field of reservoir development technology. Background Technology

[0002] The oil-water interface is a crucial parameter for reservoir reserve calculation. Currently, domestic and international scholars utilize various methods for identifying the oil-water interface in reservoirs, including direct methods such as core profile analysis, dynamic data analysis, well logging interpretation, oil testing, and geochemical determination, as well as indirect methods such as formation pressure estimation, capillary pressure prediction, seismic attribute analysis, water breakthrough time-production depth intersection, and karst hill topography. In the later stages of development, the imbalance between reserves and production in old oilfields is becoming increasingly prominent, making exploration and reserve enhancement increasingly difficult. To increase proven reserves and maintain a balance between reserves and production, the exploration direction of old oilfields should shift from shallow and medium-depth conventional sandstone reservoirs to deep buried hill reservoirs, and the exploration philosophy should shift from simply increasing proven reserves to maximizing economic benefits. For blocky bottom-water buried hill reservoirs with layered structures, determining the original oil-water interface of the trap is a critical step, providing significant reference for calculating newly proven reserves, selecting test production layers, and determining development methods. Summary of the Invention

[0003] This invention provides a method for determining the original oil-water interface of a blocky bottom-water buried hill reservoir. It comprehensively considers the trap type and reservoir-permeability characteristics of the blocky bottom-water buried hill reservoir, and integrates multiple technical means such as well logging, well logging, gas logging, and test production evaluation to accurately calculate the original oil-water interface of the blocky bottom-water buried hill reservoir with a layered structure, providing a basis for reserve evaluation and development deployment.

[0004] The technical solution adopted in this invention is a method for determining the original oil-water interface in a blocky bottom-water buried hill reservoir. In a single formation trap, a structurally favorable location is selected to implement a test well, and the preliminary original oil-water interface h of the formation trap is obtained through geological information. i Then, the perforation layer was selected to conduct test production on the test well. When the overall water cut of the test well during the evaluation period did not exceed 10%, the initial original oil-water interface h was determined. i Equal to the final original oil-water interface h u When the overall water cut of the test well exceeds 10% during the evaluation period, the preliminary original oil-water interface is reviewed and corrected to accurately calculate the final original oil-water interface.

[0005] Furthermore, the geological information includes gas logging, geochemical logging, and well logging.

[0006] Furthermore, the oil-water interface was determined through gas logging, geochemical logging, and well logging.

[0007] Furthermore, a location where the total hydrocarbon value of the gas logging curve decreases significantly is selected as the oil-water interface h1 determined by gas logging; geochemical logging directly analyzes core, cuttings, and wellbore core samples, and uses the results of geochemical pyrolysis gas chromatography analysis to determine the oil-water layer, which is selected as the oil-water interface h2 determined by geochemical logging; and a location where the resistivity of the same lithological section changes significantly is selected as the oil-water interface h3 determined by logging.

[0008] Furthermore, the location where the total hydrocarbon value of a gas logging curve significantly decreases is determined as follows: An initial total hydrocarbon value (TG) is selected from the well section of the gas logging curve where the total hydrocarbon value stabilizes after an increase. i Record a total hydrocarbon value (TG) at regular intervals. i+1 TG i TG i+1 All values ​​are the average total hydrocarbon values ​​at all measurement points within a certain length. Based on this, the rate of decline of the total hydrocarbon value is calculated, d. i =(TG) i -TG i+1 ) / TG i If there are 5 consecutive decrease rate values ​​d i ~d i+5 If all values ​​are between 10% and 15%, then the total hydrocarbon value (TG) is considered to be between 10% and 15%. i The midpoint of all corresponding measurement points is the location where the total hydrocarbon value of the gas measurement curve decreases significantly, i.e., h1. The location where the resistivity changes significantly within the same lithological segment is determined as follows: Within the same lithological segment, select a measurement point RT with stable and relatively high resistivity. i A resistivity value RT is recorded at regular intervals. i+1 RT i RT i+1 All values ​​are the average resistivity values ​​at all measurement points within a certain length. Based on this, the rate of decrease in resistivity is calculated, d. i =(RT) i -RT i+1 ) / RT i If there are 5 consecutive decrease rate values ​​d i ~d i+5 If the resistivity is between 10% and 15%, then the resistivity value RT is considered to be... i The midpoint of all corresponding measurement points is the location where the resistivity value changes significantly, i.e., h3.

[0009] Furthermore, the absolute values ​​of the differences between h1 and h2, h1 and h3, and h2 and h3 are n1, n2, and n3, respectively, i.e., n1 = |h1 - h2|, n2 = |h1 - h3|, and n3 = |h2 - h3|. When n1, n2, and n3 are all no greater than 10, h i= (h1+h2+h3) / 3; When at least one of n1, n2, and n3 is greater than 10, the weights of the three methods need to be determined based on statistical laws, i.e., h i = (h1*i1+h2*i2+h3*i3) / (i1+i2+i3); where i1, i2, and i3 are the sample numbers of the three oil-water interface values ​​determined according to the statistical law of neighboring blocks.

[0010] Furthermore, during the sample statistics process, h1, h2, and h3 need to be compared with the actual trial production patterns. The oil-water interface value with the smallest difference from the actual trial production patterns is included in the statistical sample, while the value with the largest difference is discarded.

[0011] Furthermore, when there are multiple test wells in the block, the initial original oil-water interface is taken as the average value of each well.

[0012] Furthermore, when selecting the perforation site for the test production well, the top boundary of the perforated section is selected from the top of the buried hill formation or the top of the concentrated development of the dominant reservoir rock, and the bottom boundary of the perforated section is selected at the initial original oil-water interface h. i The specific location depends on the drilling, logging, and well logging data.

[0013] Furthermore, when the overall water cut of the test well exceeds 10% during the evaluation period, the initial original oil-water interface h... i If deviations exist, then it is necessary to use the initial production data to re-evaluate the initial oil-water interface h. i After correction, the final original oil-water interface h is obtained. u h u =h b -k×f w ×(h b -h t )

[0014] Where: h u —The final original oil-water interface, m;

[0015] h t —Vertical depth of the top boundary of the perforated section, m;

[0016] h b —Vertical depth of the bottom boundary of the perforated section, m;

[0017] f w —Comprehensive water cut during the evaluation period of the pilot well;

[0018] K—Water content fluctuation coefficient;

[0019] Among them, the water content fluctuation coefficient is the ratio of the standard deviation to the average water content of each month during the evaluation of the stable period;

[0020]

[0021]

[0022] In the formula: s 2 —Variance of moisture content in each month of the evaluation period;

[0023] m—The average water content for each month during the evaluation period;

[0024] x j —Moisture content in each month of the evaluation period;

[0025] j—Number of months in the evaluation period.

[0026] This invention discloses a method for determining the original oil-water interface of a blocky bottom-water buried hill reservoir. Its beneficial effect is that, compared with the prior art, it comprehensively considers the trap type and reservoir-permeability characteristics of the blocky bottom-water buried hill reservoir, and integrates multiple technical means such as geochemical logging, well logging, gas logging, and test production evaluation to accurately calculate the original oil-water interface of the blocky bottom-water buried hill reservoir with a layered structure, providing a basis for reserve evaluation and development deployment. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 The diagram shown is a schematic diagram of the closed top boundary structure of Dugu 105 ring in Example 1;

[0029] Figure 2 The figure shown is a composite columnar section of the Dugu 105 well in Example 1. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] To further understand the invention, the technical solution will be further described below in conjunction with specific embodiments.

[0032] Example 1:

[0033] like Figure 1 and 2 As shown in this embodiment, a method for determining the original oil-water interface of a blocky bottom-water buried hill reservoir is provided. In old oilfields with high exploration levels, using data from old well tests and production, and employing techniques such as refined seismic interpretation and comprehensive reservoir evaluation, the distribution patterns of internal reservoirs and oil layers within the buried hill are explored to identify favorable stratigraphic traps and evaluate the reservoir's potential for increased reserves. Taking the blocky bottom-water buried hill reservoir in the Shuguang Middle Buried Hill Belt in the middle section of the western slope of the western Liaohe Depression as an example, in the late Mesozoic era, after the extensional faulting of the Yanshan Movement, the regional strata were further divided by secondary faults into a series of fault-block mountains that are high in the west and low in the east, dividing the regional Proterozoic buried hill into three fault-step zones: high, medium, and low. Each fault-step zone is held together by a series of main faults, forming a monocline structure that is high in the northwest and low in the southeast. While controlling the reservoir, the main faults also divide the strata into multiple independent stratigraphic traps with a unified oil-water interface and the same temperature and pressure system. The target stratum for regional exploration and development is the Dahongyu Formation of the Changcheng System in the Middle Proterozoic. The reservoir lithology is mainly quartzite, which has a granular metamorphic texture, parallel directional structure, and well-developed fractures. The reservoir space type is pore-fracture type. Fractures are mainly tectonic fractures and secondary dissolution pores, with high-angle oblique fractures being the most prevalent. Reservoir porosity includes intergranular pores and intragranular dissolution pores. This type of reservoir with dual reservoir-permeability characteristics has unobstructed oil and gas migration channels, which is conducive to oil-water differentiation and easily forms massive stratigraphic traps with a bottom water structure and a relatively clear oil-water interface. The Dugu 105 trap is located in the middle section of the western slope of the western depression of the Liaohe Depression in the middle section of the Dugu buried hill belt of the Shuguang Oilfield. It is held by three main faults, forming a monocline structure with a high northwest and low southeast. The trap type is a fracture-type stratigraphic trap. The Proterozoic buried hill lithology in the Dugu 105 well area is mainly quartzite, with a small amount of slate. Quartzite accounts for 78%-89% of the thickness of the Proterozoic strata, with a quartz content of about 96%. It is generally gray to grayish-white, with a granular metamorphic texture, parallel oriented structure, and well-developed fractures, making it the dominant reservoir rock in this area.

[0034] In 2007, the exploratory well Dugu 105 was drilled in the block. To explore the block's production potential, Dugu 105 was put into production using a screen-tube completion method, without accurately analyzing the oil-water interface of the block. The well achieved high water cut immediately after production and was shut down in 2021, with an overall water cut as high as 88%. The trial production of Dugu 105 demonstrated that the block had sufficient bottom water and a fixed oil-water interface existed in the middle of the buried hill formation.

[0035] In 2023, appraisal well Dugu 105-1 was drilled in a favorable location within the block. Drilling, logging, and well logging data indicated that the reservoir encountered the expected levels of oil production, showing good oil-bearing potential and the ability to obtain high-yield industrial oil flows. Drawing on the experience gained from the trial production evaluation of Dugu 105 well, this invention's method for initially determining the oil-water interface was employed to comprehensively analyze and evaluate the gas logging, geochemical logging, and resistivity logging data of both Dugu 105 and Dugu 105-1 wells. Specifically, appraisal wells were drilled in structurally favorable locations within a single formation trap, and the preliminary original oil-water interface h of the formation trap was determined using geological information such as gas logging, geochemical logging, and well logging. i Then, a trial production evaluation is conducted. When the overall water cut of the trial production well does not exceed 10% during the evaluation period, the initial original oil-water interface h is determined. i The final original oil-water interface (h) is calculated when the overall water cut of the test well exceeds 10% during the evaluation period. This initial original oil-water interface is then reviewed and corrected to accurately calculate the final original oil-water interface (h) of the massive bottom-water buried hill reservoir. u .

[0036] Firstly, near the oil-water interface, where the carbon composition is incomplete, a point where the total hydrocarbon value of the gas logging curve significantly decreases is selected as the oil-water interface h1 determined by gas logging. The method for determining this point of significant decrease in the total hydrocarbon value of the gas logging curve is as follows: when the total hydrocarbon value of the gas logging curve begins to rise, it is considered that the formation has oil and gas indications. An initial total hydrocarbon value TG is selected in the well section where the total hydrocarbon value stabilizes after the rise. i A total hydrocarbon value (TG) is recorded every 5 m. i+1 TG i and TG i+1 The average total hydrocarbon value is the sum of all measurement points within 5m. Based on this, the rate of decrease in total hydrocarbon value is calculated, d. i =(TG) i -TG i+1 ) / TG i If there are 5 consecutive decrease rate values ​​d i ~d i+5 If all values ​​are between 10% and 15%, then the total hydrocarbon value (TG) is considered to be between 10% and 15%. i The midpoint of all corresponding measurement points is the location where the total hydrocarbon value of the gas logging curve significantly decreases, i.e., h1. Geochemical logging directly analyzes core, cuttings, and wellbore core samples, and uses the results of geochemical pyrolysis gas chromatography analysis to determine the oil-water layer, which is used as the oil-water interface h2 determined by geochemical logging. In buried hill formations, resistivity logging is sensitive to lithological response characteristics, but due to the existence of oil-water differences, the location where the resistivity significantly decreases within the same lithological section is used as the oil-water interface h3 determined by logging. The method for determining the location where the resistivity significantly decreases within the same lithological section is as follows: within the same lithological section, a measurement point RT with stable and relatively high resistivity is selected. i A resistivity value RT is recorded every 5m. i+1RT i and RT i+1 The resistivity is the average value of all measurement points within 5m. Based on this, the rate of decrease in resistivity is calculated, d. i =(RT) i -RT i+1 ) / RT i If there are 5 consecutive decrease rate values ​​d i ~d i+5 If the resistivity is between 10% and 15%, then the resistivity value RT is considered to be... i The midpoint of all corresponding measurement points is the location where the resistivity value decreases significantly, i.e., h3.

[0037] The oil-water interfaces h1, h2, and h3 were determined using gas logging, geochemical logging, and well logging methods. Typically, the differences between these three methods for determining the oil-water interfaces are relatively small. Let the absolute values ​​of the differences between the three oil-water interfaces be n1, n2, and n3, respectively, i.e., n1 = |h1 - h2|, n2 = |h1 - h3|, n3 = |h2 - h3|. When n1, n2, and n3 are all less than or equal to 10, we take the average of h1, h2, and h3 as the preliminary original oil-water interface h. i , i.e. h i = (h1+h2+h3) / 3; when at least one of n1, n2, and n3 is greater than 10, the weights of the three methods need to be determined based on statistical laws; at this time, h i = (h1*i1+h2*i2+h3*i3) / (i1+i2+i3); where i1, i2, and i3 are the sample numbers of the three oil-water interface values ​​determined according to the statistical laws of neighboring blocks. During the sample statistics process, the oil-water interfaces h1, h2, and h3 determined by the three methods need to be compared with the actual test production patterns. The oil-water interface value with the smallest difference from the actual test production pattern is included in the statistical sample, while the value with the largest difference is discarded. When there are multiple test production wells in a block, the initial original oil-water interface can be taken as the average value of each well. The oil-water interface values ​​h1, h2, and h3 determined in this way are -2683m, -2673m, and -2674m, respectively, and n1, n2, and n3 are 10, 9, and 1, respectively, all less than or equal to 10. i = (h1+h2+h3) / 3 = -2677m, that is, the initial original oil-water interface is -2677m.

[0038] The preliminary original oil-water interface h of the blocky bottom water buried hill reservoir was determined. i Subsequently, the perforation horizon of Dugu 105-1 well was selected. The top boundary of the perforation section was selected at the top of the area where the dominant reservoir rock, quartzite, is concentrated. The bottom boundary of the perforation section was selected above the initial original oil-water interface at -2677m.

[0039] Under normal circumstances, the initial oil-water interface h is determined.i This method is relatively accurate and can effectively guide the selection of perforation zones. When the overall water cut of the test well does not exceed 10% during the evaluation period, it is considered that the bottom boundary of the perforated well section is selected above the oil-water interface, and there is no need to correct the original oil-water interface value using test well data. When the overall water cut of the test well exceeds 10%, the initial original oil-water interface h... i If a deviation exists, it can be assumed that the bottom boundary of the perforated section was selected below the initial original oil-water interface, resulting in partial bottom water production and high water cut in the well. In this case, test production data is needed to re-evaluate the initial original oil-water interface h. i After correction, the final original oil-water interface h of the blocky bottom-water buried hill reservoir was obtained. u .

[0040] The final original oil-water interface of a massive bottom-water buried hill reservoir is calculated using the following formula:

[0041] h u =h b -k×f w ×(h b -h t )

[0042] Where: h u —The final determined original oil-water interface, m;

[0043] h t —Vertical depth of the top boundary of the perforated section, m;

[0044] h b —Vertical depth of the bottom boundary of the perforated section, m;

[0045] f w —Comprehensive water cut during the evaluation period of the pilot well;

[0046] K—Water content fluctuation coefficient;

[0047] Among them, the water content fluctuation coefficient is the ratio of the standard deviation to the average water content of each month during the evaluation of the stable period;

[0048]

[0049]

[0050] In the formula: s 2 —Variance of moisture content in each month of the evaluation period;

[0051] m—The average water content for each month during the evaluation period;

[0052] x j —Moisture content in each month of the evaluation period;

[0053] j—Number of months in the evaluation period.

[0054] Formation testing was conducted in May 2023 after perforation of the well, which identified it as an oil-bearing layer. Production commenced in June, with an average daily fluid production of 16.5 tons and a daily oil production of 15.9 tons. The cumulative fluid production reached 3782 tons and the cumulative oil production reached 3538 tons during the initial phase. The comprehensive water cut during the evaluation period of the test well was [not specified]. w Only 6.5%. The overall water cut of this well is below 10%, so there is no need to correct the initial original oil-water interface. This initial original oil-water interface is the final original oil-water interface of the blocky bottom water buried hill reservoir in the Dugu 105 well area, that is, the final original oil-water interface h. u The depth is -2677m. Through trial production of appraisal wells in the Dugu 105 buried hill reservoir area, the accuracy and reliability of this invention in determining the original oil-water interface in blocky bottom-water buried hill reservoirs have been demonstrated. This is of great significance for the reserve calculation and overall development deployment of this type of reservoir. This technological invention was piloted and tested in the Dugu 105 buried hill reservoir area of ​​the Shuguang Oilfield. Based on a detailed description of the regional geological structure and reservoir characteristics, appraisal well Dugu 105-1 was deployed in the trap structure and lithologically favorable locations. Applying this technological invention, the original oil-water interface of the trap was determined. Based on this oil-water interface value, a reasonable perforation scheme was designed. After production, the well achieved high-yield industrial oil flow, a long stable production period, high cumulative oil production, and was essentially water-free. Based on this, the effective thickness of the reservoir was determined and the geological reserves were calculated, with accurate and reliable results. This technological invention provides a theoretical basis and practical foundation for the exploration, evaluation, and development deployment of blocky bottom-water buried hill reservoirs, and has significant reference and application value.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for determining the original oil-water interface in a massive bottom-water buried hill oil reservoir, characterized in that, In a single formation trap, a test well is implemented at a structurally favorable location to obtain the preliminary original oil-water interface h of the formation trap using geological information. i Then, the perforated layer was selected to conduct a test production of the test well. When the overall water cut of the test well during the evaluation period did not exceed 10%, the initial original oil-water interface h was determined. i Equal to the final original oil-water interface h u When the overall water cut of the test well exceeds 10% during the evaluation period, the preliminary original oil-water interface is reviewed and corrected to accurately calculate the final original oil-water interface; the geological information includes gas logging, geochemical logging and well logging. The oil-water interface was determined using gas logging, geochemical logging, and well logging. A location where the total hydrocarbon value of the gas logging curve significantly decreases was selected as the oil-water interface h1 determined by gas logging. Geochemical logging directly analyzed core, cuttings, and wellbore core samples, using the results of geochemical pyrolysis gas chromatography analysis to determine the oil-water layer, which was then used as the oil-water interface h2 determined by geochemical logging. A location where the resistivity of the same lithological section significantly changes was selected as the oil-water interface h3 determined by well logging. The absolute values ​​of the differences between h1 and h2, h1 and h3, and h2 and h3 are n1, n2, and n3, respectively, i.e., n1 = |h1 - h2|, n2 = |h1 - h3|, n3 = |h2 - h3|. When n1, n2, and n3 are all no greater than 10, h... i = (h1 + h2 + h3) / 3; When at least one of n1, n2, and n3 is greater than 10, the weights of the three methods need to be determined according to statistical laws, i.e., h i = (h1*i1+h2*i2+h3*i3) / (i1+i2+i3); where i1, i2, and i3 are the sample numbers of the three oil-water interface values ​​determined according to the statistical laws of neighboring blocks; when the comprehensive water cut of the test well exceeds 10% during the evaluation period, the initial original oil-water interface h i If deviations exist, then it is necessary to use the initial production data to re-evaluate the initial oil-water interface h. i After correction, the final original oil-water interface h is obtained. u , Where: h u —The final original oil-water interface, m; h t —Vertical depth of the top boundary of the perforated section, m; h b —Vertical depth of the bottom boundary of the perforated section, m; f w —Comprehensive water cut during the evaluation period of the pilot well; K—Water content fluctuation coefficient; Among them, the water content fluctuation coefficient is the ratio of the standard deviation to the average water content of each month during the evaluation period; in, ; In the formula: s 2 —Variance of moisture content in each month of the evaluation period; m—The average water content for each month during the evaluation period; x j —Moisture content in each month of the evaluation period; j—Number of months in the evaluation period.

2. The method for determining the original oil-water interface of a massive bottom-water buried hill reservoir according to claim 1, characterized in that, The location where the total hydrocarbon value of a gas logging curve decreases significantly is determined as follows: An initial total hydrocarbon value (TG) is selected from the well section of the gas logging curve where the total hydrocarbon value stabilizes after an increase. i Record a total hydrocarbon value (TG) at regular intervals. i+1 TG i and TG i+1 The average total hydrocarbon value is the sum of all measured points within a certain length. Based on this, the rate of decline of the total hydrocarbon value is calculated, d. i =(TG) i -TG i+1 ) / TG i If there are 5 consecutive decrease rate values ​​d i ~d i+5 If all values ​​are between 10% and 15%, then the total hydrocarbon value (TG) is considered to be between 10% and 15%. i The midpoint of all corresponding measurement points is the location where the total hydrocarbon value of the gas measurement curve decreases significantly, i.e., h1. The location where the resistivity changes significantly within the same lithological segment is determined as follows: Within the same lithological segment, select a measurement point RT with stable and relatively high resistivity. i A resistivity value RT is recorded at regular intervals. i+1 RT i and RT i+1 Given the average resistivity values ​​at all measurement points within a certain length, the rate of decrease in resistivity, d, is calculated based on this average. i =(RT i -RT i+1 ) / RT i If there are 5 consecutive decrease rate values ​​d i ~d i+5 If the resistivity is between 10% and 15%, then the resistivity value RT is considered to be... i The midpoint of all corresponding measurement points is the location where the resistivity value changes significantly, i.e., h3.

3. The method for determining the original oil-water interface of a massive bottom-water buried hill reservoir according to claim 1, characterized in that, During the sample statistics process, h1, h2, and h3 need to be compared with the actual trial production patterns. The oil-water interface value with the smallest difference from the actual trial production patterns is included in the statistical sample, while the value with the largest difference is discarded.

4. The method for determining the original oil-water interface of a massive bottom-water buried hill reservoir according to claim 1, characterized in that, When selecting the perforation site for test production, the top boundary of the perforated section should be chosen at the top of the buried hill or the top of the concentrated development of the dominant reservoir rock, and the bottom boundary should be chosen at the initial original oil-water interface h. i Above.

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