Study On Effective Water Injection Development Policy For Abnormal High Pressure And Low Permeability Complex Fault Block Reservoir

As a special type of low permeability reservoir, abnormal high pressure highly faulted reservoir is characteresticed as started pressure gradient, heavily stress sensitivity, poor reservoir properties, serious heterogeneity and complex border types, all of which make it different from common low permeability reservoirs. As a result, a good understanding of the percolation mechanism and special development characteristics of such reservoir is of high value and guiding significance to make rational development programs and get a cost-efficient development in such reservoirs.At present, the dynamic performance of waterflooding development in K1g3reservoir is that the reservoir pressure drops quickly, the well pressure and production rate decreases rapidly, and the injection rate is too small but the injection pressure is very high. To solve these problems, this paper mainly carries out the study of the following aspects and achieves corresponding results.Firstly, carry out the research and analysis on the K1g3reservoir geological characteristics. Taking advantage of all kinds of geological research reports and log interpretation results, etc. based on sedimentology and petroleum geology theory and methods get the re-understanding of the reservoir geological characteristics.Secondly, carry out the experimental study on the mechanism of fluid flow:1) Experiment on threshold pressure gradient and get its relationship with permeability and fluidty;2) Experimental research on core stress censitivity and get the expression between permeability and effect stress;3) Carry out the parallel displacement experiments with different permeability differential cores and get the curves of permeability differential and velocity ratio;4) Experimental study on the injection water quality systems and get the optimal injection water quality.Thirdly, carry out research on the ability of injection wells and correspondent measures to improve the ability to absorb water. Use existing data to make a dynamic analysis of injection wells, sums up the current problems encountered during the course of water flooding, and puts forward appropriate improvement measures.At last, combined reservoir engineering theory and methods with the results of experimental study on the mechanism of fluid flow, the effective technological policies in reservoir waterflooding are studied.1) Carry out the study on reasonable injection-production pattern well, establish a method to calculate the ultimate injection-production well spacing considering the effect of threshold pressure gradient and stress sensitivity, and get corresponding charts.2) Based on the sweep efficiency calculation method of complicated fault-block reservoir, get the efficiency of each injection well.3) Establish the theory of the effect of permeability max-min ratio on vertical sweep efficiency and get injection wells’ vertical profile conformance.4) Conduct research on injection-production pressure system to determine the reasonable bottomhole flowing pressure of oil and injection wells and the pressure level of reservoir formation and injectin time.5) Deduce a new deliverability equation considering the stress sensitivity and then study the effect of formation pressure maintenance on well deliverability and get corresponding chartss.6) Make an analysis and evaluation of the injection-production pressure system of each block.