Main Influence Factors Of Sweep Efficiency By Water Flooding

Sweep efficiency of water flooding is the key to improving the recovery ratio in waterflooding oilfield.At present the sweep efficiency of water flooding research results mostly for self-contained reservoir,and the fault block reservoir because of its complicated geological features such as complex structure,quantities of faults,small fault block,lots of drive types and difficulty on forming perfect well system,makes the dynamic features with integrity reservoir are not the same,the main control factors are also different.Therefore it is not suitable to use the same equations to calculate the sweep efficiency.We found that the dip angle,width,thickness,permeability,permeability ratio,viscosity ratio,speed of water injection have kinds of effect on sweep efficiency of water flooding via investigation.However,most of the early researches are focus on analyzing the single effect factor on the fault block reservoir,there is no study on comprehensive analysis the relative influence of various factor.As a result,the author focused on these issues above,in view of the above factors,focused on studying camber fault block reservoir(an obvious kind fault block reservoir),made geological modeling,and based on 109 fault block of Dongxin oil field,using the orthogonal analysis method to set up 64 groups of models,and using the numerical simulation method to calculate the water flood sweep efficiency.Then according to the method of multiple regression analysis,we found the main control factor of camber fault block reservoir,and obtain the correlation formula.The research results show that: for positive rhythm camber fault block reservoir,the main controlling factors affecting the sweep efficiency are the oil-water viscosity ratio,permeability ratio,width,permeability and water injection speed.As for the reverse rhythm camber fault block reservoir,main controlling factors are viscosity,permeability,permeability,width,water injection speed,dip angle and thickness.Then we take sensitivity analysis on the factors like permeability,permeability ratio,viscosity ratio and water injection speed to determine the important degree of the influencing factors and summarize the results of each main controlling factors impact on the spread coefficient.Finally we forecasted the final sweep efficiency by the geological and production data of different fault block reservoirs and took Y12 block of Dongxin oil field as an example to conduct applied research,and used the formula of sweep efficiency to analyze the development effect.We got the new recovery curves with the rate of water content by using the sweep efficiency,and compared with the actual data of the oil field.