Calculation method for current oil-water interface depth of developed edge-bottom water reservoir

Abstract

The invention discloses a method for calculating the current oil-water interface depth of a developed edge-bottom water reservoir. The method comprises the steps of defining parameters; determining an oil-water interface upshift volume calculation formula; determining a current oil-water interface depth solving formula; obtaining a plurality of Vn / V2 values; and calculating the difference value between each Vn / V2 value and the Qn / Q2 value to obtain the depth Hn of the current oil-water interface. The method for calculating the current oil-water interface depth of the developed edge-bottom water reservoir provided by the invention has the following beneficial effects: clearer understanding of current reservoir characteristics is facilitated, qualitative understanding in actual work is improved to quantitative calculation, so that quantitative identification of a reservoir strong water flooding area and a remaining oil enrichment area is guided; and the method is used as a basis for reasonable and efficient adjustment and development of the oil reservoir in the next step to guide deployment of development schemes and facilitate further improvement of the oil reservoir recovery efficiency. The edge-bottom water reservoir is generally developed in various oil fields in the world, so that the method has high popularization value at the same time.

Description

Technical Field

[0001] The invention belongs to the technical field of oil reservoir development, and particularly relates to a method for calculating the current oil-water interface depth of a developed edge-bottom water oil reservoir. Background Art

[0002] Edge-bottom water reservoirs refer to reservoirs with water bodies at the edge or bottom. Due to the obvious density difference between oil and water, after differentiation and adjustment, oil is enriched in the high part of the reservoir, while water bodies are located at the edge or bottom of the reservoir. The contact surface between oil and water is called the oil-water interface. If the oil-water interface is very large, much larger than the vertical cross section of the oil layer, such a reservoir is a bottom water reservoir, and its oil layer is generally thicker. If the oil-water interface is relatively small, about the same as the vertical cross section of the oil layer, such a reservoir is an edge water reservoir, and its oil layer is generally relatively thin and has a certain structural dip. However, there is no absolutely clear dividing line between bottom water reservoirs and edge water reservoirs, so they are collectively referred to as edge-bottom water reservoirs. Edge-bottom water reservoirs are a common type of reservoir. During the development of this type of reservoir, as the degree of crude oil recovery gradually increases, the edge-bottom water pushes the oil-water interface upward as a whole. In the area affected by the oil-water interface, the crude oil in the reservoir pores is displaced by the edge water, presenting a strong water flooding state.

[0003] The study of the distribution law of remaining oil in developed bottom water reservoirs is of great significance for improving the recovery rate of reservoirs. With the increasing degree of production of bottom water reservoirs, the oil-water boundary is gradually rising as a whole. The reservoirs in the affected areas experience edge water cleaning, and the oil saturation is significantly reduced, which is first excluded from the potential area of ​​remaining oil enrichment. Then, quantitative calculation of the oil-water interface of the current reservoir can, on the one hand, exclude the strong water flooding area below the current oil-water interface, ensure the identification of the remaining oil enrichment area, and reasonably deploy new wells to tap the potential. On the other hand, it can guide the deployment of reservoir development adjustment plans, including well network deployment, coverage demonstration and seepage field adjustment.

[0004] At present, the main method for obtaining the oil-water interface is to calculate the original oil-water interface of the reservoir, but no quantitative calculation of the oil-water interface depth of the developed edge-bottom water reservoir has been found through retrieval. With the development and mobilization of the reservoir, the reservoir characteristics and oil-water interface depth at the current stage are the focus of reservoir engineers. Summary of the invention

[0005] In order to solve the above problems, the object of the present invention is to provide a method for calculating the current oil-water interface depth of an already developed edge-bottom water reservoir.

[0006] In order to achieve the above object, the method for calculating the current oil-water interface depth of an developed edge-bottom water reservoir provided by the present invention comprises the following steps performed in sequence:

[0007] 1) Define the parameters including comprehensive adjustment time, oil-water contact depth, and oil-bearing area at each stage from reservoir development to the present;

[0008] 2) Based on the parameters in step 1), a calculation formula for the upward displacement volume V2 of the oil-water interface during the period from the time T1 when the first plan is implemented to the time T2 when the second plan is implemented;

[0009] 3) Based on the parameters in step 1), determine the time from the implementation time T2 to the current time T2 of the second plan n The volume V of the oil-water interface moving upward during the time period n The calculation formula of

[0010] 4) Implement the second plan from the new well time T2 to the current time T n The volume V of the oil-water interface moving upward during the time period n The ratio of the oil-water interface upward displacement volume V2 from the time T1 of the first plan to the time T2 of the second plan is taken as the current oil-water interface depth H n Solve formulas;

[0011] 5) Read multiple sets of different contour depth values ​​D from the reservoir microstructure map and oil-bearing area distribution map m And the oil-bearing area P above this depth value m Data, each pair of data as an array, the contour depth values ​​D in different arrays m And the oil-bearing area P above this depth value m As the current oil-water interface depth H n and the current oil-water interface depth H n Oil-bearing area S n Substitute the current oil-water interface depth H into the above n Solve the formula to obtain multiple V n / V2 value;

[0012] 6) Calculate each V n / V2 value and Q n The difference between the values ​​of / Q2, where the cumulative oil production Q2 from the time T1 to the time T2 of the second plan implementation of the new well, and the cumulative oil production Q2 from the time T2 to the current time T n Cumulative oil production Q n Obtained from the oil well production report query; then |V n / V2-Q n / Q2|The contour depth value D corresponding to the minimum absolute value m And the oil-bearing area P above this depth value m As the current oil-water interface depth H n and the current oil-water interface depth Hn Oil-bearing area S n The optimal solution of the current oil-water interface depth H can be obtained. n .

[0013] In step 1), the method for defining parameters including the comprehensive adjustment time, oil-water interface depth, and oil-bearing area at each stage from reservoir development to the present is:

[0014] According to the sequence of multiple comprehensive adjustment times from reservoir discovery to the later stage, the comprehensive adjustment times are defined as T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20, T21, T30, T41, T52, T63, T74, T85, T96, n ; Wherein, T1 represents the time of the first well implementation plan after the discovery and development of the reservoir. At this time, the original oil-water interface depth of the reservoir is H1, and the original oil-bearing area above the original oil-water interface depth H1 is S1; T2 represents the time of the second well implementation plan of the reservoir. At this time, the oil-water interface depth of the reservoir is H2, and the oil-bearing area above the oil-water interface depth H2 is S2. The cumulative oil production from the first well implementation time T1 to the second well implementation time T2 is Q2; T n Indicates the current time, when the second plan is implemented, the new well time T2 to the current time T n The cumulative oil production is Q n The oil-water interface depth of the reservoir is the current oil-water interface depth H n , the current oil-water interface depth H n The oil-bearing area above is S n .

[0015] In step 2), the calculation formula for the upward displacement volume V2 of the oil-water interface during the time period from the first implementation of the new well T1 to the second implementation of the new well T2 is:

[0016] V2=(S1-S2)*(H1-H2); (1)

[0017] Among them, the original oil-water interface depth H1 and the original oil-bearing area S1 are read through the reservoir microstructure map and the oil-bearing area distribution map; the oil-water interface depth H2 is read through the interpretation results of the wells drilled in the second adjustment plan; the oil-bearing area S2 is read through the reservoir microstructure map and the oil-bearing area distribution map.

[0018] In step 3), the second plan is implemented from the new well time T2 to the current time T n The volume V of the oil-water interface moving upward during the time period n The calculation formula is:

[0019] V n =(S2-S n )*(H2-H n ) (2)

[0020] Among them, H n The current oil-water interface depth is H. n The oil-bearing area above is S n .

[0021] In step 4), the current oil-water interface depth H n The solution formula is:

[0022] V n / V2 = [(S2-S n )*(H2-H n )] / [(S1-S2)*(H1-H2)] (3).

[0023] The method for calculating the current oil-water interface depth of the developed edge-bottom water reservoir provided by the present invention has the following beneficial effects: it helps to obtain a clearer understanding of the current reservoir characteristics, and improves from the qualitative understanding in actual work to quantitative calculation, so as to guide the quantitative identification of the strong water-flooded area and the residual oil-rich area of ​​the reservoir, and serves as the basis for the next step of reasonable and efficient adjustment and development of the reservoir, guides the deployment of development plans, and helps to further improve the reservoir recovery rate. Since edge-bottom water reservoirs are commonly developed in oil fields around the world, this method also has a high promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A flow chart of the method for calculating the current oil-water interface depth of an already developed edge-bottom water reservoir provided by the present invention.

[0025] Figure 2 Schematic diagram of oil-water boundary of edge-bottom water reservoir in the present invention. (a) is the microstructure and oil-bearing area distribution diagram of XX reservoir, and (b) is the cross-section diagram of reservoir A to B.

[0026] Figure 3 This is a diagram showing the microstructure and oil-bearing area distribution of the YY oil layer in the fault block in the embodiment of the present invention.

[0027] Figure 4 This is a comprehensive interpretation diagram of well logging of an oil well in an embodiment of the present invention. DETAILED DESCRIPTION

[0028] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] like Figure 1 As shown, the method for calculating the current oil-water interface depth of the developed edge-bottom water reservoir provided by the present invention comprises the following steps performed in sequence:

[0030] 1) Define the parameters including comprehensive adjustment time, oil-water contact depth, and oil-bearing area at each stage from reservoir development to the present;

[0031] The development process of oil reservoirs will go through multiple stages of comprehensive adjustments to improve the injection and production well network and tap the potential of the remaining oil-rich areas to achieve reasonable and efficient development of the oil reservoirs. According to the order of the multiple comprehensive adjustment times from the discovery of the oil reservoir to the later stage, the comprehensive adjustment times are defined as T1, T2, T3...T n ; Among them, T1 represents the time of the first implementation of the new well plan after the discovery of the oil reservoir and the development. At this time, the original oil-water interface depth of the oil reservoir is H1, and the original oil-bearing area above the original oil-water interface depth H1 is S1; after years of development, as the cumulative oil production increases, the oil-water interface changes accordingly. T2 represents the time of the second implementation of the new well plan for the oil reservoir. At this time, the oil-water interface depth of the oil reservoir is H2, and the oil-bearing area above the oil-water interface depth H2 is S2. The cumulative oil production from the first implementation of the new well plan time T1 to the second implementation of the new well plan time T2 is Q2, such as Figure 2 As shown; T n Indicates the current time, when the second plan is implemented, the new well time T2 to the current time T n The cumulative oil production is Q n At this time, the oil-water interface depth of the reservoir is the current oil-water interface depth H n , the current oil-water interface depth H n The oil-bearing area above is S n .

[0032] After two or more adjustments and developments, according to the reservoir development data and the wells encountered, the known parameters are: the original oil-water interface depth H1, the original oil-bearing area S1, the oil-water interface depth H2, the oil-bearing area S2, the cumulative oil production Q2 from the time T1 of the first plan to the time T2 of the second plan to the time T n Cumulative oil production Q n ;

[0033] 2) Based on the parameters in step 1), the calculation formula for the upward displacement volume V2 of the oil-water interface during the period from the time T1 when the first plan is implemented to the time T2 when the second plan is implemented is determined:

[0034] V2=(S1-S2)*(H1-H2); (1)

[0035] Among them, the original oil-water interface depth H1 and the original oil-bearing area S1 are read through the reservoir microstructure map and the oil-bearing area distribution map; the oil-water interface depth H2 is read through the interpretation results of the wells encountered in the second adjustment plan; the oil-bearing area S2 is read through the reservoir microstructure map and the oil-bearing area distribution map;

[0036] 3) Based on the parameters in step 1), determine the time from the implementation time T2 to the current time T2 of the second plann The volume V of the oil-water interface moving upward during the time period n The calculation formula is:

[0037] V n =(S2-S n )*(H2-H n ) (2)

[0038] Among them, H n The current oil-water interface depth is H. n The oil-bearing area above is S n ;

[0039] 4) Implement the second plan from the new well time T2 to the current time T n The volume V of the oil-water interface moving upward during the time period n The ratio of the oil-water interface upward displacement volume V2 from the time T1 of the first plan to the time T2 of the second plan is taken as the current oil-water interface depth H n Solution formula:

[0040] V n / V2 = [(S2-S n )*(H2-H n )] / [(S1-S2)*(H1-H2)] (3)

[0041] 5) Read multiple sets of different contour depth values ​​D from the reservoir microstructure map and oil-bearing area distribution map m And the oil-bearing area P above this depth value m Data, each pair of data is regarded as an array, see Table 1, and the contour depth values ​​D in different arrays are m And the oil-bearing area P above this depth value m As the current oil-water interface depth H n and the current oil-water interface depth H n Oil-bearing area S n Substituting into the solution formula shown in formula (3), we can obtain multiple V n / V2 value; the interval of the contour line depth value is determined according to the required accuracy. Generally, the interval of the contour line depth value is less than 2 meters to meet the actual application of reservoir development and analysis.

[0042] 6) Calculate each V n / V2 value and Q n The difference between the values ​​of / Q2, where the cumulative oil production Q2 from the time T1 to the time T2 of the second plan implementation of the new well, and the cumulative oil production Q2 from the time T2 to the current time T n Cumulative oil production Q nObtained from the oil well production report query; then |V n / V2-Q n / Q2|The contour depth value D corresponding to the minimum absolute value m And the oil-bearing area P above this depth value m As the current oil-water interface depth H n and the current oil-water interface depth H n Oil-bearing area S n The optimal solution of the current oil-water interface depth H can be obtained. n .

[0043] Table 1. Statistics of different contour depth values ​​and their corresponding oil-bearing areas

[0044]

[0045] like Figure 3 As shown, the method of the present invention is described in detail below by taking the oil reservoir on the south side of fault No. 50 of a certain oil field xx block as an example:

[0046] (1) Characteristics of reservoirs during initial development;

[0047] T1: June 2001; original oil-water interface depth H1: 1804 meters; original oil-bearing area S1: 0.24 square kilometers.

[0048] (2) Secondary adjustment of reservoir characteristics;

[0049] T2: June 2007; oil-water interface depth H2: 1796 meters; oil-bearing area S2: 0.173 square kilometers; cumulative oil production in the T1-T2 period Q2: 102,000 tons.

[0050] Note: Well X15 is the second adjustment implementation well, which was drilled in June 2007. The current oil-water interface depth H2 is 1796 meters as read from the comprehensive interpretation of electrical logging. Figure 4 The oil-bearing area S2 is the oil-bearing area above the depth value of the 1796m contour line. The microstructure and oil-bearing area map reads: 0.173 square kilometers. The cumulative oil production Q2 during the T1-T2 period, that is, the cumulative oil production of the southern reservoir from June 2001 to June 2007, is 102,000 tons from the oil well production report.

[0051] (3) The statistical table of different contour depth values ​​and their corresponding oil-bearing areas is shown in Table 2;

[0052] Note: For the reservoir on the south side of fault No. 50 in block xx, the depth interval of contour lines is 2 meters. The depth values ​​of contour lines in Table 2 are Figure 3 Read, the oil-bearing area above the depth value of the contour line is from Figure 3 Measurement reading.

[0053] (4)Q n The cumulative oil production of the southern oil reservoir from July 2007 to the present is 36,600 tons according to the oil well production report.

[0054] (5) According to the current oil-water interface depth H n Solution formula:

[0055] V n / V2=[(S2-S n )*(H2-H n )] / [(S1-S2)*(H1-H2)]

[0056] Sequentially change (D1, P1) to (D m , P m ) arrays are used as the current oil-water interface depth H n and the current oil-water interface depth H n Oil-bearing area S n Substitute into the above solution formula to obtain multiple V n / V2 value;

[0057] (6) Calculate each V n / V2 value and Q n / Q2 value difference, the calculation results are shown in Table 3, and then |V n / V2-Q n / Q2|The contour depth value D corresponding to the minimum absolute value m And the oil-bearing area P above this depth value m As the current oil-water interface depth H n and the current oil-water interface depth H n The oil-bearing area above is S n The optimal solution of the current oil-water interface depth H can be obtained. n .

[0058] In this embodiment, Q n / Q2=3.66 / 10.2=0.36;

[0059] |V n / V2-Q n / Q2|The minimum absolute value is 0.11, and the corresponding contour depth value is 1792 meters, which is the current oil-water interface depth H. n .

[0060] Table 2. Statistics of different contour depth values ​​and their corresponding oil-bearing areas

[0061]

[0062]

[0063] Table 3. Calculation results statistics

[0064]

[0065] The current oil-water interface depth H is required n It is 1792 meters, which is 12 meters higher than the original oil-water interface H1 of 1804 meters. Therefore, within the oil-bearing area above the current oil-water interface depth, the remaining oil-rich area can be identified and five new wells can be deployed to tap the potential.

Claims

1. A method for calculating the current oil-water interface depth of an developed edge-bottom water reservoir, characterized by: The calculation method comprises the following steps performed in sequence: 1) Define the parameters including comprehensive adjustment time, oil-water contact depth, and oil-bearing area at each stage from reservoir development to the present; 2) Based on the parameters in step 1), a calculation formula for the upward displacement volume V2 of the oil-water interface during the period from the time T1 when the first plan is implemented to the time T2 when the second plan is implemented; 3) Based on the parameters in step 1), determine the time from the implementation time T2 to the current time T2 of the second plan n The volume V of the oil-water interface moving upward during the time period n The calculation formula of 4) Implement the second plan from the new well time T2 to the current time T n The volume V of the oil-water interface moving upward during the time period n The ratio of the oil-water interface upward displacement volume V2 from the time T1 of the first plan to the time T2 of the second plan is taken as the current oil-water interface depth H n Solve formulas; 5) Read multiple sets of different contour depth values ​​D from the reservoir microstructure map and oil-bearing area distribution map m And the oil-bearing area P above this depth value m Data, each pair of data as an array, the contour depth values ​​D in different arrays m And the oil-bearing area P above this depth value m As the current oil-water interface depth H n and the current oil-water interface depth H n Oil-bearing area S n Substitute the current oil-water interface depth H into the above n Solve the formula to obtain multiple V n / V2 value; 6) Calculate each V n / V2 value and Q n The difference between the values ​​of / Q2, where the cumulative oil production Q2 from the time T1 to the time T2 of the second plan implementation of the new well, and the cumulative oil production Q2 from the time T2 to the current time T n Cumulative oil production Q n Obtained from the oil well production report query; then |V n / V2-Q n / Q2|The contour depth value D corresponding to the minimum absolute value m And the oil-bearing area P above this depth value m As the current oil-water interface depth H n and the current oil-water interface depth H n Oil-bearing area S n The optimal solution of the current oil-water interface depth H can be obtained. n .

2. The method for calculating the current oil-water interface depth of a developed edge-bottom water reservoir according to claim 1, characterized in that: In step 1), the method for defining parameters including the comprehensive adjustment time, oil-water interface depth, and oil-bearing area at each stage from reservoir development to the present is: According to the sequence of multiple comprehensive adjustment times from reservoir discovery to the later stage, the comprehensive adjustment times are defined as T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20, T21, T30, T41, T52, T63, T74, T85, T96, n ; Wherein, T1 represents the time of the first well implementation plan after the discovery and development of the reservoir. At this time, the original oil-water interface depth of the reservoir is H1, and the original oil-bearing area above the original oil-water interface depth H1 is S1; T2 represents the time of the second well implementation plan of the reservoir. At this time, the oil-water interface depth of the reservoir is H2, and the oil-bearing area above the oil-water interface depth H2 is S2. The cumulative oil production from the first well implementation time T1 to the second well implementation time T2 is Q2; T n Indicates the current time, when the second plan is implemented, the new well time T2 to the current time T n The cumulative oil production is Q n The oil-water interface depth of the reservoir is the current oil-water interface depth H n , the current oil-water interface depth H n The oil-bearing area above is S n .

3. The method for calculating the current oil-water interface depth of a developed edge-bottom water reservoir according to claim 2, characterized in that: In step 2), the calculation formula for the upward displacement volume V2 of the oil-water interface during the time period from the first implementation of the new well T1 to the second implementation of the new well T2 is: V2=(S1-S2)*(H1-H2); (1) Among them, the original oil-water interface depth H1 and the original oil-bearing area S1 are read through the reservoir microstructure map and the oil-bearing area distribution map; the oil-water interface depth H2 is read through the interpretation results of the wells drilled in the second adjustment plan; the oil-bearing area S2 is read through the reservoir microstructure map and the oil-bearing area distribution map.

4. The method for calculating the current oil-water interface depth of a developed edge-bottom water reservoir according to claim 2, characterized in that: In step 3), the second plan is implemented from the new well time T2 to the current time T n The volume V of the oil-water interface moving upward during the time period n The calculation formula is: V n =(S2-S n )*(H2-H n ) (2) Among them, H n The current oil-water interface depth is H. n The oil-bearing area above is S n .

5. The method for calculating the current oil-water interface depth of a developed edge-bottom water reservoir according to claim 2, characterized in that: In step 4), the current oil-water interface depth H n The solution formula is: <h2 style=";text-align:left;direction:ltr">V<h2 style=";text-align:left;direction:ltr"> n <h2 style=";text-align:left;direction:ltr"> / V2 = [(S2-S<h2 style=";text-align:left;direction:ltr"> n <h2 style=";text-align:left;direction:ltr"> )*(H2-H<h2 style=";text-align:left;direction:ltr"> n <h2 style=";text-align:left;direction:ltr"> )] / [(S1-S2)*(H1-H2)] (3)。

Images