Disconnection and control body oil reservoir water diversion rate calculation chart and application thereof
By using a water fractionation calculation chart for fault-controlled reservoirs, the problem of poor water drive development caused by the heterogeneity of fault-controlled reservoirs was solved, and the well network and injection-production strategies were optimized, thereby improving the recovery rate.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2024-11-22
- Publication Date
- 2026-05-22
AI Technical Summary
In fault-controlled reservoirs, the high heterogeneity and complex and variable water drive channels lead to poor production results, and existing well patterns and injection-production design methods are difficult to effectively guide water drive development.
A chart for calculating the water distribution rate of a fault-controlled reservoir is provided. By establishing a relationship between the cumulative water injection volume and the pressure of the effective oil well, the type of inter-well channel can be identified, guiding the deployment of well networks and the optimization of injection and production strategies.
By using intuitive and simple methods to determine whether the well channel is singular, the injection method can be adjusted to expand the water drive coverage and improve the recovery rate of the well group.
Smart Images
Figure CN122072800A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of waterflooding development technology for carbonate oil and gas reservoirs, and in particular to a calculation chart for water fractionation in fault-controlled reservoirs and its application. Background Technology
[0002] As oilfield development continues, the challenges it faces are increasing. In terms of development methods, water injection remains the dominant method in domestic oilfields, accounting for approximately 80% of the total reserves. Regarding reservoir type, the vast majority of domestic reservoirs are continental clastic sedimentary rocks. Compared to the marine sedimentary reservoirs predominantly found in overseas oilfields, continental sedimentary reservoirs exhibit poorer reservoir properties and severe heterogeneity. During water injection development, the heterogeneity of the reservoir leads to a significant directional bias in water displacement, impacting the effectiveness of waterflooding.
[0003] Reasonable well network and injection-production strategy are among the most critical issues in water-drive oilfield development. Well network deployment and injection-production strategy determination is a complex system engineering project. When designing well network and injection-production schemes, it is necessary to fully consider the heterogeneity of reservoir rock fluid parameters and development dynamic characteristics to obtain a well network deployment method and injection-production strategy that match them.
[0004] Traditional well pattern and injection-production design methods involve developing several well pattern schemes or injection-production schemes based on the actual geology and development conditions of the reservoir, and then comparing and analyzing the schemes using reservoir engineering methods or reservoir numerical simulation to select the optimal scheme.
[0005] Zhao Jiyong, Fan Jianming, He Yonghong, et al. Optimization of injection and production parameters for horizontal well development in ultra-low permeability tight oil reservoirs [J]. Petroleum Exploration and Development. Based on the characteristics of Changqing Oilfield in Ordos Basin, this paper proposes the basic principles for determining injection and production parameters for horizontal well water injection development and provides calculation charts.
[0006] The Shunbei oil and gas field is located in the heart of the Tarim Basin, situated on the tectonic saddle of the northern and central Tarim uplifts—the Shuntogole low uplift. Influenced by multiple tectonic phases, the regional faults have complex origins. The main faults in the block are No. 1 and No. 5. Influenced by northeast- and northwest-trending stresses, these faults have reversed, resulting in a highly fragmented and heterogeneous reservoir. As reservoir energy decreases, reservoir development has gradually shifted from elastic drive to water injection for energy replenishment. Due to the strong heterogeneity of the fault-controlled reservoir and the complex and variable water drive pathways, the extraction efficiency is very poor.
[0007] In view of this, and to address the shortcomings of existing technologies, this invention provides a water distribution ratio calculation chart for fault-controlled reservoirs and its application. Targeting the characteristics of the Shunbei oil and gas field, this invention establishes a water distribution ratio chart that can effectively identify inter-well channel types, providing strong support for implementing differentiated and precise water injection strategies tailored to each well. Summary of the Invention
[0008] The purpose of this invention is to provide a chart for calculating the water fraction of a fault-controlled reservoir and its application, providing theoretical guidance for optimizing injection and production parameters during water-drive well injection.
[0009] To achieve the above-mentioned objectives, the technical solution of this invention is as follows:
[0010] On the one hand, the present invention provides a water distribution rate calculation chart for a fault-controlled reservoir, which is a chart showing the relationship between the cumulative water injection volume and the effective well pressure under different water distribution rates.
[0011] Preferably, the water separation rate refers to the percentage of water used for effective energy replenishment of the oil well relative to the total injected water volume.
[0012] More preferably, the calculation steps for the water separation rate are as follows:
[0013] (1) Determine the baseline value: Calculate the liquid production per unit pressure drop before water injection and convert it to the underground volume;
[0014] (2) Calculate the water volume: Based on the stage pressure drop and the liquid production per unit pressure drop before water injection, and with reference to the production trend before water injection, calculate the underground volume (normalized) that should be produced under the stage pressure drop, and calculate the supplementary volume based on the difference between the actual underground volume produced in the stage and the normalized volume.
[0015] (3) Calculate the water distribution rate: Oil well water distribution rate = oil well water distribution volume / water injection volume of water injection well.
[0016] More preferably, in step (1) setting the reference value, the unit pressure drop production before water injection = total production of oil well before water injection / pressure drop of oil well before water injection.
[0017] Preferably, the different water separation rates refer to water separation rates of 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100%, respectively.
[0018] Preferably, the effective well pressure = initial well pressure at a certain stage - (volume produced at that stage - volume injected at that stage × water separation rate) / volume produced per unit pressure drop before water injection.
[0019] On another note, this invention provides the application of the above-mentioned fault-controlled reservoir water fractionation calculation chart in the water drive development process of oil and gas reservoirs.
[0020] Preferably, the application refers to: obtaining the actual pressure of oil wells at different stages through downhole pressure testing, and then applying the actual pressure to the reservoir water fractionation calculation chart of the fault control body to obtain the change of water fractionation with the change of water injection volume.
[0021] More preferably, the water separation rate changes either steadily or fluctuates.
[0022] More preferably, when the change in water separation rate is stable, it indicates that the inter-well channel is a single channel.
[0023] More preferably, when the water separation rate fluctuates, it indicates that the inter-well channel is not a single channel.
[0024] The beneficial effects of this invention are as follows:
[0025] This invention discloses a novel method for evaluating the water distribution rate of injection wells. The effective well pressure and cumulative water injection volume are plotted onto a reservoir gas distribution rate calculation chart within a fault-controlled body to obtain changes in the water distribution rate, thereby determining whether the inter-well pathway is singular. Based on different inter-well pathways, different injection methods are adjusted to expand water drive reach and improve well group recovery. The method for evaluating the water distribution rate of injection wells disclosed in this invention has the advantages of being intuitive, simple, and easy to use. Attached Figure Description
[0026] Figure 1 This is a diagram illustrating the calculation of water fraction in a fault-controlled reservoir, as disclosed in this invention.
[0027] Figure 2 The water fraction is obtained by applying the water fraction calculation chart of the fault-controlled reservoir disclosed in this invention. Detailed Implementation
[0028] The following non-limiting embodiments are intended to enable those skilled in the art to gain a more comprehensive understanding of the present invention, but do not limit the invention in any way. The following content is merely an exemplary description of the scope of protection claimed by the present invention, and those skilled in the art can make various changes and modifications to the invention based on the disclosed content, which should also fall within the scope of protection claimed in this application.
[0029] The present invention will be further described below by way of specific embodiments. Unless otherwise specified, all chemical reagents used in the embodiments of the present invention were obtained through conventional commercial means. Unless otherwise specified, all contents mentioned below are mass contents. Unless otherwise specified, it is understood that the process was carried out at room temperature.
[0030] Example 1: Establishing a computational diagram
[0031] 1. Liquid production per unit pressure drop before water injection
[0032] The unit pressure drop production before water injection is the amount of fluid produced when the average formation pressure drops by 1 MPa before water injection; the unit pressure drop production before water injection = total fluid production of the oil well before water injection / pressure drop of the oil well before water injection.
[0033] 2. Fixed water separation rate
[0034] Water separation ratio refers to the percentage of water effectively replenishing the oil well out of the total injected water volume. It is calculated by taking advantage of the pressure difference before and after the well becomes effective, determining the replenished volume, and then dividing the replenished volume by the injected water volume. The calculation mainly involves the following three steps:
[0035] (1) Determine the baseline value: Calculate the liquid production per unit pressure drop before water injection and convert it to the underground volume;
[0036] (2) Calculate the water volume: Based on the stage pressure drop and the liquid production per unit pressure drop before water injection, and with reference to the production trend before water injection, calculate the underground volume (normalized) that should be produced under the stage pressure drop, and calculate the supplementary volume based on the difference between the actual underground volume produced in the stage and the normalized volume.
[0037] (3) Calculate the water distribution rate: Oil well water distribution rate = oil well water distribution volume / water injection volume of water injection well.
[0038] 3. Effective oil well pressure at any time after water injection.
[0039] Effective well pressure = initial well pressure at a certain stage - (volume produced at that stage - volume injected at that stage × water separation rate) / volume produced per unit pressure drop before water injection.
[0040] 4. Draw a water separation rate chart.
[0041] Based on a water separation rate ranging from 0% to 100%, the pressure changes of the affected oil wells are predicted in 10% increments, and a relationship graph between cumulative water injection volume and the pressure of the affected oil wells is established, as shown below. Figure 1 As shown.
[0042] Example 2: Application of Calculation Chart
[0043] Downhole pressure testing can obtain the actual pressure of an oil well at different stages. Plotting this actual pressure onto a graph reveals how the water separation ratio changes with the injected water volume. Figure 2 As shown. By Figure 2 It can be seen that the water separation rate is stable and remains at 50%, indicating that the well channel is a single channel.
[0044] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A calculation chart for water fraction in a fault-controlled reservoir, characterized in that, The water distribution rate calculation chart of the fault-controlled reservoir is a graph showing the relationship between the cumulative water injection volume and the effective well pressure under different water distribution rates.
2. The water separation ratio calculation chart for fault-controlled reservoirs according to claim 1, characterized in that, The water separation rate refers to the percentage of water used for effective energy replenishment of the oil well relative to the total injected water volume.
3. The calculation chart for water separation rate of a fault-controlled reservoir according to claim 2, characterized in that, The calculation steps for the water separation rate are as follows: (1) Determine the baseline value: Calculate the liquid production per unit pressure drop before water injection and convert it to the underground volume; (2) Calculate the water volume: Based on the stage pressure drop and the liquid production per unit pressure drop before water injection, and with reference to the production trend before water injection, calculate the underground volume (normalized) that should be produced under the stage pressure drop, and calculate the supplementary volume based on the difference between the actual underground volume produced in the stage and the normalized volume. (3) Calculate the water distribution rate: Oil well water distribution rate = oil well water distribution volume / water injection volume of water injection well.
4. The water separation ratio calculation chart for fault-controlled reservoirs according to claim 3, characterized in that, In step (1) setting the benchmark value, the unit pressure drop production before water injection = total production of oil well before water injection / pressure drop of oil well before water injection.
5. The water separation ratio calculation chart for fault-controlled reservoirs according to claim 1, characterized in that, The different water separation rates refer to water separation rates of 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100%.
6. The water separation ratio calculation chart for fault-controlled reservoirs according to claim 1, characterized in that, The effective well pressure = initial well pressure at a certain stage - (volume produced at that stage - volume injected at that stage × water separation rate) / volume produced per unit pressure drop before water injection.
7. The application of the fault-controlled reservoir water fraction calculation chart according to any one of claims 1-6 in the water drive development process of oil and gas reservoirs.
8. The application according to claim 7, characterized in that, The application refers to the following: by obtaining the actual pressure of oil wells at different stages through downhole pressure testing, the actual pressure can be applied to the reservoir water fractionation calculation chart of the fault control body to obtain the change of water fractionation with the change of water injection volume.
9. The application according to claim 8, characterized in that, The water separation rate is either stable or fluctuating.
10. The application according to claim 9, characterized in that, When the change in water separation rate is stable, it indicates that the inter-well channel is a single channel; When the water separation rate fluctuates, it indicates that the inter-well channel is not a single channel.