CN-121976779-A - Subsequent water flooding diving method based on flow field comprehensive analysis

CN121976779ACN 121976779 ACN121976779 ACN 121976779ACN-121976779-A

Abstract

The invention discloses a subsequent water drive submersible displacement method based on flow field comprehensive analysis, and belongs to the technical field of residual oil submersible displacement in the middle and later high water content stages of oilfield development. The method comprises the steps of quantitatively identifying dominant seepage channels based on streamline distribution, oil saturation field and water passing times of a target oil reservoir, dividing six types of residual oil and defining distribution characteristics of the six types of residual oil, and combining pressure system research and reasonable injection and extraction ratio regulation and control to provide differential mining countermeasures for different types of residual oil. The invention effectively solves the development problems of high water content and low extraction degree in the subsequent water flooding stage of the polymer flooding, and can obviously improve the recovery ratio and the development benefit of the oil reservoir.

Inventors

YANG ZHAO
ZHANG CHENMING
LIU CHENGTING
LIU JINZI
CHEN HAO
SHI JIANWU

Assignees

东北石油大学三亚海洋油气研究院

Dates

Publication Date: 20260505
Application Date: 20260408

Claims (9)

1. The subsequent water flooding mining method based on the flow field comprehensive analysis is characterized by comprising the following steps of: The method comprises the steps of meshing an oil reservoir to be regulated into a plurality of oil reservoir blocks, and obtaining a characteristic curve of pump efficiency and pump port pressure of an oil pumping unit, wherein the meshing of the oil reservoir to be regulated into the plurality of oil reservoir blocks comprises the steps of obtaining reservoir static properties and development dynamic data of the oil reservoir to be regulated, constructing a three-dimensional mesh model of the oil reservoir to be regulated based on the reservoir static properties and the development dynamic data, and meshing the oil reservoir to be regulated into the plurality of oil reservoir blocks, wherein the reservoir static properties comprise lithology, porosity and permeability, and the development dynamic data comprise accumulated water injection quantity, liquid production quantity and water content; Determining the formation pressure system characteristics of an oil reservoir to be adjusted, and determining the formation pressure limit of an oil reservoir block according to the formation pressure system characteristics; Measuring the bubble point pressure of crude oil of each oil reservoir block, and determining the lowest flow pressure of each oil reservoir block according to the bubble point pressure theory; establishing an association equation of the pump port pressure of the pumping unit pump and the flow pressure of the oil reservoir block, substituting the pump port pressure corresponding to the preset pump efficiency minimum threshold value in the characteristic curve of the pump efficiency and the pump port pressure into the association equation of the pump port pressure of the pumping unit pump and the flow pressure of the oil reservoir block, and solving to obtain the minimum reasonable flow pressure; and determining a control strategy of the injection ratio of the oil reservoir to be regulated according to the stratum pressure limit and the flow pressure limit of each oil reservoir block so as to determine the diving measures of the residual oil of each type of the oil reservoir to be regulated.
2. The subsequent water flooding mining method based on flow field comprehensive analysis according to claim 1, wherein the streamline distribution, the reservoir water flow multiple and the oil saturation of each reservoir block are required to be obtained before the formation pressure system characteristics of the reservoir to be adjusted are determined; According to the water flow multiple and the oil saturation of the oil reservoir, identifying the dominant seepage channel of the oil reservoir to be adjusted through quantitative analysis, wherein the dominant seepage channel specifically comprises the following components: Determining a streamline with the water storage multiple of more than or equal to 100 and the oil saturation of 0.2 to 0.3 in all oil reservoir blocks as a high-permeability path for fluid flow in the oil reservoir to be regulated, namely an initial dominant seepage channel; Determining a dominant seepage channel of a high-water-content well from the initial dominant seepage channel by fitting the relation between the water ratio of the oil reservoir and the water breakthrough probability in an oil reservoir block containing the initial dominant seepage channel, wherein the water breakthrough probability is that the water content of water breakthrough of an oil field production well exceeds 80% for the first time; determining a streamline with oil saturation less than 0.2 and flow speed greater than 4m/s in a dominant seepage channel of a high water-containing well as the dominant seepage channel; the dominant seepage direction of the dominant seepage channel is a dense area with streamline distribution.
3. The subsequent water flooding mining method based on flow field comprehensive analysis according to claim 2, wherein the dominant seepage channel of the high water content well is determined from the initial dominant seepage channel by fitting the relation between the water content multiple of the oil reservoir and the water content breakthrough probability, and specifically comprises the following steps: establishing a quantitative relation model of water breakthrough probability and oil reservoir water passing multiple, wherein the formula is as follows: ; In the formula, For the water cut-through probability, Is the water passing multiple of the oil reservoir, 、 Solving by a maximum likelihood estimation method as a fitting coefficient; Setting a preset water breakthrough probability threshold value, substituting the water breakthrough probability threshold value into a quantitative relation model, and calculating to obtain critical oil reservoir water passing times; and screening out a streamline with the water content of the oil reservoir larger than the critical water content and the water content of the corresponding oil reservoir block exceeding 80% from the initial dominant seepage channel to obtain the dominant seepage channel of the high-water-content well.
4. The subsequent water flooding mining method based on flow field comprehensive analysis according to claim 1, wherein the determining the formation pressure system characteristic of the reservoir to be adjusted and determining the formation pressure limit of the reservoir block according to the formation pressure system characteristic specifically comprises: acquiring the liquid yield, the oil yield and the water content of each oil reservoir block; acquiring the formation pressure system characteristics of the oil field to be adjusted by using an oil reservoir engineering and numerical simulation method; And respectively establishing correlation equations of formation pressure system characteristics and the liquid production, the oil production and the water content of the oil reservoir block to be regulated by utilizing a multiple linear regression model, substituting preset oil production constraint conditions, preset water content constraint conditions and preset oilfield reservoir protection constraint conditions into the correlation equations, and solving to obtain formation pressure ranges meeting all constraints, namely the formation pressure limit of the oil reservoir block.
5. The subsequent water flooding mining method based on flow field comprehensive analysis according to claim 4, wherein the oil reservoir engineering and numerical simulation method are utilized to obtain the pressure system characteristics of the oil reservoir to be adjusted, and the method specifically comprises the following steps: adopting pressure recovery well test, interference well test and yield splitting technology to obtain bottom hole pressures, stratum permeability and pressure guide coefficients of different layers of each oil reservoir block; Drawing a block plane pressure contour map by using a statistical analysis method according to the bottom hole pressure, the stratum permeability and the pressure guide coefficient of different layers of each oil reservoir block, and identifying a pressure high-value region, a pressure low-value region and a pressure transition region; acquiring pressure data of each horizon in the vertical direction by adopting a layering test technology, and calculating interlayer pressure difference of an oil reservoir to be adjusted; constructing a three-dimensional geological model of an oil reservoir to be regulated; Importing a three-dimensional geological model into numerical simulation software, and performing numerical simulation on the interlayer pressure difference of the oil reservoir to be regulated by adopting a black oil model so as to simulate the pressure field evolution processes of different development stages of the oil reservoir to be regulated, thereby obtaining numerical simulation results, namely a pressure transmission rule between wells in the horizontal direction and interlayer pressure transfer efficiency in the vertical direction; and forming pressure system characteristics of horizontal direction pressure gradient distribution and vertical direction interlayer pressure difference distribution according to the interlayer pressure difference of the oil reservoir to be regulated and the numerical simulation result.
6. The method for subsequent water flooding mining based on flow field comprehensive analysis according to claim 4, wherein the determining process of the formation pressure limit of the reservoir block specifically comprises: Adopting multiple linear regression analysis to respectively construct correlation equations of formation pressure and liquid production, oil production and water content, wherein the formulas are as follows: ; ; P+ ; In the formula, In order to adjust the liquid production of the oil reservoir, In order to produce oil, the oil is produced, The water content is the water content of the water-based paint, In order to be the formation pressure, 、、、、 And Is a regression coefficient; Substituting preset constraint conditions into the correlation equation, and solving to obtain formation pressure ranges meeting all constraints, namely a formation pressure limit; The preset constraint conditions comprise that the oil yield is larger than or equal to the lower limit of the economic oil yield of the block, the water content is smaller than or equal to the upper limit of the economic water content of the block, the stratum pressure is smaller than or equal to the reservoir fracture pressure, and the reservoir fracture pressure is larger than or equal to the crude oil saturation pressure; the lower limit of the economic oil production of the block and the upper limit of the economic water content of the block are determined according to the development cost and the price of crude oil.
7. The subsequent water flooding method based on flow field comprehensive analysis as claimed in claim 1, wherein the determining process of the flow pressure limit specifically comprises: Measuring the bubble point pressure Pb of the crude oil of the block; Based on bubble point pressure theory, in order to avoid degassing phenomenon in oil extraction process, the flow pressure of the oil reservoir block is greater than or equal to the product of crude oil bubble point pressure and safety coefficient, and the product of crude oil bubble point pressure and safety coefficient is the lowest flow pressure of the oil reservoir block ; Establishing an association equation of the pump port pressure and the flow pressure, wherein the formula is as follows: ; In the formula, Is the pressure of the pump mouth of the pumping unit pump, As the flow pressure of the reservoir block, 、、 The density, the gravity acceleration and the depth of the well fluid in the oil reservoir block well group are respectively, The pressure correction parameters are used for quantifying the sum of all factors which lead to pressure drop except the gravity of the liquid column in the process that the fluid enters the well group from the oil reservoir and rises to the pump port; Setting the lowest threshold of pump efficiency Finding out a pump port pressure value corresponding to the lowest pump efficiency threshold value in the characteristic curve of the pump efficiency and the pump port pressure, substituting the pump port pressure value into a correlation equation of the pump port pressure and the flow pressure to obtain the flow pressure Is a value of (2); Introducing correction factors Correcting flow pressure With minimum flow pressure Maximum value between, a flow pressure limit is obtained, expressed as: ; In the formula, The flow pressure limit is set to a value, Is a correction coefficient.
8. The subsequent water flooding mining method based on flow field comprehensive analysis according to claim 1, wherein the determining the injection ratio regulation strategy of the oil reservoir to be regulated according to the formation pressure limit and the flow pressure limit of each oil reservoir block specifically comprises: Determining the relation between the injection ratio and the water content and recovery ratio of an oil reservoir block, wherein the injection ratio range is 0.8-1.2, and IPR is the injection ratio; For the region where the actual formation pressure is less than the lower limit value of the formation pressure limit and the actual flowing pressure is less than the flowing pressure limit, the injection ratio is adjusted to be 1.1-1.2; For a region where the actual formation pressure is greater than or equal to the lower limit value of the formation pressure limit and less than or equal to the upper limit value of the formation pressure limit and the actual flowing pressure is greater than or equal to the flowing pressure limit and less than or equal to 9.8MPa, the injection-recovery ratio is adjusted to be 0.95-1.05; for the region where the actual formation pressure is greater than the upper limit value of the formation pressure limit and the actual flowing pressure is greater than the flowing pressure limit, adjusting the injection-recovery ratio to 0.8-0.9; And acquiring the liquid yield, the oil yield, the water content, the formation pressure and the flow pressure to be regulated once every 3 months, substituting the correlation equation of the formation pressure system characteristics and the liquid yield, the oil yield and the water content of the oil reservoir block to be regulated and the correlation equation of the pump port pressure and the flow pressure, and recalibrating the injection ratio parameters to realize the real-time optimization of the strategy.
9. The subsequent water-driven oil-mining method based on flow field comprehensive analysis of claim 2, wherein the type of the residual oil of the oil reservoir to be adjusted is determined according to streamline distribution of the oil reservoir block corresponding to the dominant seepage channel, the type of the residual oil of the oil field to be adjusted comprises thick oil layer top residual oil, shunt line position residual oil, phase change region residual oil, physical property deterioration part residual oil, interlayer interference residual oil and sand body edge residual oil, and the oil-mining measure of the residual oil comprises: For the residual oil at the top of the thick oil layer, a long rubber cylinder is adopted to block a high-permeability section at the bottom of the thick oil layer, or a horizontal well is used for sectional injection and production to change the flow direction and drive the residual oil at the top to move downwards; the residual oil at the position of the shunt line is changed by adjusting the injection intensity of the adjacent water injection well or implementing periodic water injection, so that the residual oil is promoted to migrate to the production well; the residual oil in the phase change region and the residual oil at the position with poor physical properties are transformed into the hypotonic reservoir by adopting a fracturing technology, so that the diversion capacity of the hypotonic reservoir is improved; the residual oil is disturbed between layers, and the implementation layers are subdivided and recombined or an intelligent well completion tool is adopted for selective production and water injection so as to relieve the contradiction between layers; The oil remaining at the edge of the sand body improves the sweep efficiency by arranging an encryption well or a sidetracking well at the edge or optimizing the parameters of a mining pattern at the edge; and (3) implementing mechanical water shutoff or chemical water shutoff for the water channeling problem caused by the dominant seepage channel, and performing deep profile control on the high water absorption layer to block or bypass the high seepage channel.

Description

Subsequent water flooding diving method based on flow field comprehensive analysis Technical Field The application relates to the technical field of residual oil mining in a later high water content stage in oilfield development, in particular to a subsequent water flooding mining method based on flow field comprehensive analysis. Background Polymer flooding (polymer flooding for short) is an important technical means for improving the recovery ratio of an oil field, and the high-efficiency exploitation of crude oil is realized by injecting polymer solution into an oil reservoir, improving the water phase fluidity ratio and the swept volume. However, after the polymer flooding is finished and the polymer flooding stage is carried out, the oil reservoir faces multiple development contradictions that the polymer is adsorbed and retained in the stratum pores in the polymer flooding process, so that the stratum heterogeneity is aggravated, the injected water is easy to flow along a high-permeability channel in the subsequent water flooding process, a water channeling phenomenon is formed, and the oil yield is rapidly reduced. In the prior art, a general injection ratio regulating and controlling technology based on dynamic production data is adopted, and the injection ratio regulating coefficient is calculated by adopting an empirical formula through statistics of the overall liquid yield, the oil yield and the water content change trend of a block, so that the water injection intensity is regulated. However, in the prior art, the water injection intensity is not controlled pertinently in the development area of the dominant seepage channel, and serious water channeling still exists, while the water injection is insufficient in the low-permeability residual oil enrichment area due to general adjustment, residual oil cannot be effectively utilized, and finally, the development problems of high water content and low recovery degree in the subsequent water flooding stage of polymer flooding are caused, the recovery ratio is small, and the requirement of the development benefit of an oil field is difficult to meet. Disclosure of Invention Based on the above, it is necessary to provide a subsequent water flooding method based on flow field comprehensive analysis. The invention adopts the following technical scheme: The invention provides a subsequent water flooding diving method based on flow field comprehensive analysis, which comprises the following steps: gridding the oil reservoir to be regulated into a plurality of oil reservoir blocks, and obtaining a characteristic curve of pump efficiency and pump port pressure of a pumping unit pump; Determining the formation pressure system characteristics of an oil reservoir to be adjusted, and determining the formation pressure limit of an oil reservoir block according to the formation pressure system characteristics; Measuring the bubble point pressure of crude oil of each oil reservoir block, and determining the lowest flow pressure of each oil reservoir block according to the bubble point pressure theory; establishing an association equation of the pump port pressure of the pumping unit pump and the flow pressure of the oil reservoir block, substituting the pump port pressure corresponding to the preset pump efficiency minimum threshold value in the characteristic curve of the pump efficiency and the pump port pressure into the association equation of the pump port pressure of the pumping unit pump and the flow pressure of the oil reservoir block, and solving to obtain the minimum reasonable flow pressure; and determining a control strategy of the injection ratio of the oil reservoir to be regulated according to the stratum pressure limit and the flow pressure limit of each oil reservoir block so as to determine the diving measures of the residual oil of each type of the oil reservoir to be regulated. Preferably, the reservoir to be regulated is gridded into a plurality of reservoir blocks, which specifically comprises: The method comprises the steps of obtaining reservoir static properties of an oil reservoir to be adjusted and development dynamic data, wherein the reservoir static properties comprise lithology, porosity and permeability, and the development dynamic data comprise accumulated water injection quantity, liquid production quantity and water content; Based on the static property of the reservoir and the development dynamic data, a three-dimensional grid model of the reservoir to be adjusted is built, and the reservoir to be adjusted is grid into a plurality of reservoir blocks. Preferably, before determining the formation pressure system characteristics of the reservoir to be adjusted, further comprising: obtaining streamline distribution, oil reservoir water passing times and oil saturation of each oil reservoir block; According to the water flow multiple and the oil saturation of the oil reservoir, identifying the dominant seepage channel of the oil res