Water plugging and well selecting method for oil well

Abstract

The invention discloses an oil well water plugging and well selecting method. The method comprises the steps that data information of all oil wells in a target area is collected; determining a plurality of decision factors corresponding to each oil well according to the data information; and comprehensive evaluation and judgment are conducted according to the multiple decision factors, and a water plugging measure target well is determined. By means of the scheme, the success rate of oil well water plugging measures can be increased, then the oil well water drive yield is increased, and the recovery efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas field development, and in particular to an oil well water plugging and well selection method. Background Art

[0002] At present, my country's oil fields generally enter the high water content or ultra-high water content exploitation period. 60% of the recoverable reserves of oil fields and more than 80% of the annual output come from high water content reservoirs with a water content greater than 80%. At the same time, due to the primary and secondary heterogeneity of the formation, differences in fluid mobility and other reasons, water flow dominant channels are formed in the formation, resulting in water cones, water channeling, and water fingering, causing some oil wells to see water or be flooded prematurely, and water drive inefficient or ineffective circulation. This makes water plugging and profile control technology an effective means for oil fields to improve the effect of water injection development and achieve stable oil reservoir production.

[0003] The existing methods for selecting wells and layers for water plugging in oil fields are mainly based on previous construction experience, or the target wells for water plugging construction are determined based on a single parameter of the oil well. The decision-making basis is single, and in the actual production process, many factors are ambiguous and uncertain, which often leads to a low success rate of water plugging construction measures or a short effective period of plugging. Summary of the invention

[0004] The invention provides an oil well water plugging and well selection method, which improves the success rate of oil well water plugging measures, thereby increasing the oil well water drive production and improving the recovery rate.

[0005] To this end, the present invention provides the following technical solutions:

[0006] A method for water plugging and well selection in an oil well, the method comprising:

[0007] Collect data on oil wells in the target area;

[0008] Determine a plurality of decision factors corresponding to each oil well according to the data;

[0009] A comprehensive evaluation is performed based on the various decision factors to determine the target wells for water plugging measures.

[0010] Optionally, the data include: oil well data, corresponding water well data, and reservoir properties.

[0011] Optionally, the multiple decisions include any two or more of the following: permeability decision, water absorption profile decision, wellhead pressure drop decision, and water cut decision.

[0012] Optionally, determining the permeability decision factor corresponding to each oil well includes:

[0013] Calculating an average permeability based on the permeability of each sublayer in the target area;

[0014] The permeability variation coefficient of each small layer is calculated according to the average permeability, and the permeability variation coefficient is used as the permeability decision factor of the oil well.

[0015] Optionally, determining the water absorption profile decision factor corresponding to the oil well according to the data includes:

[0016] Calculating the average water absorption percentage and water absorption coefficient of variation of the oil well;

[0017] The water absorption profile decision factor of the oil well is calculated according to the average water absorption percentage and the water absorption variation coefficient.

[0018] Optionally, determining the wellhead pressure drop decision factor of the oil well according to the data includes:

[0019] Calculating the wellhead pressure drop of the oil well;

[0020] The wellhead pressure drop is regularized to obtain a wellhead pressure drop decision factor of the oil well.

[0021] Optionally, determining the water content decision factor of the oil well according to the data includes:

[0022] The water content rising speed of the oil well is calculated, and the water content rising speed is used as a water content decision factor of the oil well.

[0023] Optionally, performing comprehensive evaluation and judgment based on the multiple decision factors to determine the target well for water plugging measures includes:

[0024] Calculating a comprehensive decision factor of each oil well based on multiple decision factors of the oil well;

[0025] According to the comprehensive decision-making factors of each oil well, the target wells for water plugging measures are determined.

[0026] Optionally, determining the target wells for water plugging measures according to the comprehensive decision factors of each oil well includes:

[0027] The oil wells whose comprehensive decision factors are greater than the set threshold are taken as target wells for water plugging measures.

[0028] A computer-readable storage medium stores a computer program, which, when executed by a processor, executes the steps of the above-mentioned oil well water plugging and well selection method.

[0029] The oil well water plugging and well selection method provided by the present invention makes a comprehensive evaluation based on multiple factors, for example, comprehensively considers multiple factors such as permeability variation coefficient, water absorption profile, wellhead pressure drop curve and water content decision, and finally obtains the comprehensive decision factor of each oil well, thereby selecting the target well for water plugging measures. The scheme of the present invention can greatly improve the success rate of oil well water plugging measures, thereby increasing the oil well water drive production and improving the recovery rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The invention discloses a flow chart of a method for water plugging and selecting a well in an oil well. DETAILED DESCRIPTION

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0032] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments cannot be described one by one here, but the embodiments of the present invention are not therefore limited to the following embodiments.

[0033] In view of the problems existing in the well selection method commonly used in water plugging construction in oil fields, the present invention provides a method for selecting wells for water plugging in oil wells, which performs comprehensive evaluation based on multiple factors, for example, comprehensively considering multiple factors such as permeability variation coefficient, water absorption profile, wellhead pressure drop curve and water cut decision, and finally obtains a comprehensive decision factor for each oil well, thereby selecting the target well for water plugging measures.

[0034] like Figure 1 As shown, it is a flow chart of the oil well water plugging and well selection method provided by the present invention, which comprises the following steps:

[0035] Step 101, collecting data of each oil well in the target area.

[0036] The data may include but are not limited to:

[0037] ① Oil well data, including: liquid production reflecting oil well productivity, oil well production capacity, water content, recovery degree, and water content increase rate;

[0038] ②Corresponding water well data, including: apparent water absorption index, water absorption thickness, and PI value reflecting the water absorption capacity of the water well;

[0039] ③ Reservoir properties, including: average permeability, vertical permeability distribution, permeability variation coefficient, treatment layer thickness, and successor layer production capacity.

[0040] The above data are obtained based on logging or well testing data.

[0041] Step 102: Determine a plurality of decision factors corresponding to each oil well according to the data.

[0042] The multiple decisions include but are not limited to any two or more of the following: permeability decision, water absorption profile decision, wellhead pressure drop decision, and water cut decision.

[0043] The calculation of the decision factors corresponding to the above decisions is described in detail below.

[0044] (1) Permeability decision factors

[0045] During the development of oil wells, high permeability layers are prone to form dominant seepage channels, and formation water advances along the dominant seepage channels, causing uneven reservoir utilization and making it difficult to mobilize oil in low permeability layers. For oil well water plugging and well selection, wells with relatively high average permeability often produce relatively large amounts of water. Therefore, wells with relatively high average permeability are selected as target wells for water plugging construction. From the perspective of layer selection, the greater the difference in permeability between the various sub-layers of the target oil well, the more uneven the water drive, and the lower the utilization of the low permeability layer. Therefore, when selecting the water plugging layer for the target well, decisions can be made based on the permeability variation coefficient of each sub-layer, and layers with larger permeability variation coefficients can be selected for water plugging.

[0046] In a non-limiting embodiment, the average permeability can be calculated based on the permeability of each sublayer in the target area; the permeability variation coefficient of each sublayer can be calculated based on the average permeability, and the permeability variation coefficient can be used as the permeability decision factor of the oil well.

[0047] The calculation formulas for the average permeability and permeability variation coefficient are as follows:

[0048] Average penetration rate:

[0049] Permeability variation coefficient:

[0050] The meanings of the parameters in the formula are as follows:

[0051] Average penetration rate;

[0052] n: number of small layers;

[0053] k v : Permeability variation coefficient;

[0054] k i : the permeability of the ith layer, unit: mD;

[0055] h i : the thickness of the ith layer, unit: m;

[0056] H: total thickness, unit: m.

[0057] It should be noted that the division of each sublayer can be based on the lithology or oil saturation of each layer.

[0058] (2) Water absorption profile decision factors

[0059] When the water absorption profile decision method is used for decision making, the decision factor of the well can be calculated based on the water absorption (injection volume) percentage and the water absorption variation coefficient of the well, and the oil well corresponding to the layer with a large decision factor can be selected for water plugging.

[0060] To this end, the average water absorption percentage and the water absorption variation coefficient of the oil well are first calculated, and then the water absorption profile decision factor of the oil well is calculated based on the average water absorption percentage and the water absorption variation coefficient.

[0061] The percentage of water absorption of the jth layer of the i-th well: W ij The calculation formula is:

[0062] Average water absorption percentage of the i-th well The calculation formula is:

[0063] The coefficient of variation of water absorption of the i-th well is:

[0064] The decision factor for the i-th well is:

[0065] The meanings of the parameters in the formula are as follows:

[0066] q ij is the water absorption of the jth sublayer in the ith well;

[0067] n is the number of layers in the ith well;

[0068] is the minimum value of the coefficient of variation of water absorption among all wells. It is the maximum value of the coefficient of variation of water absorption among all wells.

[0069] The decision factor F(i) value of each well is calculated according to the formula, and the target well with a decision factor greater than the critical value is selected. The layer with a relatively large water absorption percentage corresponding to the target well is selected as the water plugging construction layer.

[0070] (3) Wellhead pressure drop decision factor

[0071] Specifically, the wellhead pressure drop of the oil well may be calculated; then the wellhead pressure drop is regularized to obtain a wellhead pressure drop decision factor of the oil well.

[0072] The calculation formula of wellhead pressure drop PI is:

[0073] The normalized value of the mean;

[0074] The meanings of the parameters in the formula are as follows:

[0075] p(t) is the pressure changing function with time;

[0076] q is the daily water injection volume of the injection well, unit: m 3 / d;

[0077] h is the formation thickness, in m.

[0078] The PI correction value is calculated according to the formula, and the wells whose PI correction value is less than the critical value of the decision factor are selected for water plugging.

[0079] (4) Moisture content decision factor

[0080] Generally speaking, the oil production of oil wells will decrease as the water content increases. Therefore, for water plugging, wells with higher water content should be selected for water plugging. Whether water plugging is needed is determined based on the water content. In addition to the current water content, the water content rising speed must also be calculated. If the water content is f w If the rising speed is too fast, the water content of the oil well will increase rapidly within a period of time, which is also within the scope of water plugging considerations.

[0081] The water rise rate is calculated by the following formula:

[0082]

[0083] The meanings of the parameters in the formula are as follows:

[0084] t: time, unit d;

[0085] f w : moisture content, decimal;

[0086] (f w ) max : Limit moisture content, generally 0.98, decimal;

[0087] a and b are constant values ​​obtained by simplifying the formula for water content rising rate.

[0088] According to the water cut and water cut rising speed in actual development, linear regression can be performed on the above formula to determine the parameters a and b, and the water cut at different times can be calculated by substituting back into the original formula. The water cut formula is derived to calculate the water cut rising speed. The water cut rising speed decision is consistent with the water cut decision, that is, wells with high water cut and fast water cut rising speed can be selected as target wells for water plugging measures.

[0089] Step 103, performing comprehensive evaluation based on the multiple decision factors to determine the target well for water plugging measures.

[0090] Specifically, the comprehensive decision factor of each oil well can be calculated according to the multiple decision factors of each oil well; and the target well for water plugging measures can be determined according to the comprehensive decision factor of each oil well.

[0091] For example, in a non-limiting embodiment, corresponding judgment conditions may be set for each of the above-mentioned decision factors, and oil wells that meet each condition may be used as target wells for water plugging measures.

[0092] For another example, in another non-limiting embodiment, an oil well with a comprehensive decision factor greater than a set threshold is selected as a target well for water plugging measures; or a well with the largest comprehensive decision factor in the target area is selected as a target well for water plugging measures.

[0093] Various decision factors can be expressed as follows:

[0094]

[0095] By performing weighted calculation on the above-mentioned multiple decision factors, the comprehensive decision factor FZ of each oil well is obtained, namely:

[0096]

[0097] Among them, α=(∝1∝2∝3…α n ), is the weight of the multi-factor decision factor; F ij represents the jth factor decision factor of the ith well; n represents the number of oil wells in the target area.

[0098] After calculating the multi-factor comprehensive decision factors of each oil well in the target area, select the wells with the largest factor for water plugging construction. Generally, the comprehensive decision factor is greater than 0.85, which can be selected as the target well for water plugging measures.

[0099] The oil well water plugging and well selection method provided by the present invention makes a comprehensive evaluation based on multiple factors, for example, comprehensively considers multiple factors such as permeability variation coefficient, water absorption profile, wellhead pressure drop curve and water content decision, and finally obtains the comprehensive decision factor of each oil well, thereby selecting the target well for water plugging measures. The scheme of the present invention can greatly improve the success rate of oil well water plugging measures, thereby increasing the oil well water drive production and improving the recovery rate.

[0100] For example, Liaohe Oilfield X32-Xing HX was put into production on May 21, 2008, with a well section of 1240-1507m and a production well section of 267m. It produced 7 cycles in total, with a cumulative oil production of 8912t and a cumulative water production of 47268m3. The well was shut down in January 2017 due to high water content. In the early stage, segmented steam injection and profile adjustment were implemented, and in the later stage, selective injection and production were implemented, but the effect was not obvious.

[0101] The method of the present invention is used to determine whether water plugging measures can be implemented for the well, and the following decision factors are obtained respectively:

[0102] The permeability decision factor is 0.75;

[0103] The decision factor for water absorption profile is 0.90;

[0104] The decision factor for wellhead pressure drop is 0.70;

[0105] The moisture content decision factor is 0.88;

[0106] Using the above decision factors, the multi-factor comprehensive decision factor was calculated to be 0.92.

[0107] The water plugging factor of this well is the highest among the surrounding wells, so this well is selected as the water plugging measure well.

[0108] After the well was plugged, a total of 1,200 cubic meters of plugging agent was injected. After the construction, the daily production increased by about 2.5 tons, with a significant production increase effect.

[0109] The present invention also discloses a storage medium, which is a computer-readable storage medium on which a computer program is stored. When the computer program is run, the computer program can execute Figure 1 The steps of the method shown in . The storage medium may include a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, etc. The storage medium may also include a non-volatile memory (non-volatile) or a non-transitory memory, etc.

[0110] It should be noted that the terms "including" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or apparatus.

[0111] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0112] The above embodiments may be implemented in whole or in part by software, hardware, firmware or any other combination thereof. When implemented using software, the above embodiments may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer programs are loaded or executed on a computer, the processes or functions described in the embodiments of the present application are generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium, for example, the computer instructions may be transmitted from one website site, computer, server or data center to another website site, computer, server or data center by wired or wireless means.

[0113] The embodiments of the present invention are described in detail above. The present invention is described in detail using specific implementation methods herein. The description of the above embodiments is only used to help understand the method and system of the present invention. It is only a part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should belong to the scope of protection of the present invention, and the content of this specification should not be understood as limiting the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for water plugging and well selection in oil wells, characterized in that: The method comprises: Collect data on oil wells in the target area; Determine a plurality of decision factors corresponding to each oil well according to the data; A comprehensive evaluation is performed based on the various decision factors to determine the target wells for water plugging measures.

2. The oil well water plugging and well selection method according to claim 1, characterized in that: The data include: oil well data, corresponding water well data, and reservoir properties.

3. The oil well water plugging and well selection method according to claim 1, characterized in that: The multiple decisions include any two or more of the following: permeability decision, water absorption profile decision, wellhead pressure drop decision, and water cut decision.

4. The oil well water plugging and well selection method according to claim 3, characterized in that: The permeability decision factors for each oil well include: Calculating an average permeability based on the permeability of each sublayer in the target area; The permeability variation coefficient of each small layer is calculated according to the average permeability, and the permeability variation coefficient is used as the permeability decision factor of the oil well.

5. The oil well water plugging and well selection method according to claim 3, characterized in that: Determining the water absorption profile decision factors corresponding to the oil well according to the data includes: Calculating the average water absorption percentage and water absorption coefficient of variation of the oil well; The water absorption profile decision factor of the oil well is calculated according to the average water absorption percentage and the water absorption variation coefficient.

6. The oil well water plugging and well selection method according to claim 3, characterized in that: Determining the wellhead pressure drop decision factors of the oil well according to the data includes: Calculating the wellhead pressure drop of the oil well; The wellhead pressure drop is regularized to obtain a wellhead pressure drop decision factor of the oil well.

7. The oil well water plugging and well selection method according to claim 3, characterized in that: The water content decision factors of the oil well determined according to the data include: The water content rising speed of the oil well is calculated, and the water content rising speed is used as a water content decision factor of the oil well.

8. The oil well water plugging and well selection method according to any one of claims 3 to 7, characterized in that: The comprehensive evaluation and judgment based on the multiple decision factors to determine the target wells for water plugging measures include: Calculating a comprehensive decision factor of each oil well based on multiple decision factors of the oil well; According to the comprehensive decision-making factors of each oil well, the target wells for water plugging measures are determined.

9. The oil well water plugging and well selection method according to claim 8, characterized in that: Determining the target wells for water plugging measures based on the comprehensive decision factors of each oil well includes: The oil wells whose comprehensive decision factors are greater than the set threshold are taken as target wells for water plugging measures.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the oil well water plugging and well selection method according to any one of claims 1 to 9 are executed.

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