Study On Damage Evaluation Of External Fluids And Productivity Influencing Factors Of Tight Reservoirs In Pu 34 Area

The fracturing of horizontal wells is an important means of tight reservoir development,and the problem of reservoir damage is often accompanied by fracturing stimulation.The damage evaluation of foreign fluids is the basic work for the rational and efficient development of reservoirs.This paper takes the tight reservoirs in Pu 34 area as the research object,and systematically carries out the damage evaluation of tight reservoirs such as speed sensitivity,water sensitivity,acid sensitivity,alkali sensitivity,salt sensitivity and foreign fluids.Combining experimental methods such as scanning electron microscopy,mercury intrusion experiment,X-diffraction clay minerals,etc.,the influence of foreign liquid on the microscopic pore roar characteristics of the reservoir is analyzed.Combined with the development status of 11 horizontal wells in the study area,comprehensive analysis of factors affecting productivity.The results show that the reservoirs in the study area mainly contain siltstone with poor physical properties.The fractures of the reservoir are not developed and the compressibility is good.The reservoir has weak velocity sensitivity,medium to strong water sensitivity,and medium to weak alkali sensitivity,and no acid sensitivity damage occurs.The damage rate of guar gum fracturing fluid is greater than that of slippery water,and the damage rate of water-based drilling fluid is greater than that of oil-based drilling fluid.The combination of "oil-based drilling fluid + slick water fracturing fluid" is recommended,and the maximum recovery factor is 12.535%.Factors affecting the productivity of production wells in the study area can be divided into three types: physical properties,oiliness,and damage to reservoirs caused by foreign fluids.The degree of influence is: physical properties>oil content>damage of foreign fluid to the reservoir.