Research On Drilling Fluid Technology Of Protection Coal Bed Methane Reservoir When Exploration

Human production and life demand for energy increasingly with economic development,social progress.Traditional energy supplies have seriously failed to meet the needs of economic and social development and it become a major obstacle to China's economic and social development.Therefore,we must actively seek and develop new energy resources in order to reduce dependence on traditional energy resources for Chinese economic and social development.Coalbed methane is the number of non-conventional energy resources in a resource that cannot be ignored,so its position in energy consumption in China and the world is more and more important.Based on the characteristics of coalbed gas reservoir in Gulin area and in the comprehensive collection and analysis of a number of coalbed gas exploration geological data.This Master Thesis focus analyze and identify reservoir cores of Gulin well 1#,Gulin well 2#,Gulin well 3# and Gulin well 4#.The clay content in the coalbed methane reservoir is greater than 5% is potential geological factor of causing damage of drilling fluid reservoir.The result of X-ray diffraction show that the types of clay mineral is chlorite,illite,kaolinite,which belonging to the non-expansive clay minerals.By microscopic analysis,that is,scanning electron microscope,sheet identification,surface energy spectrum analysis and so on to confirm more serious damage of drilling fluid in coalbed methane reservoir.The clay particles,leachate,chemical substances and so on in drilling fluid intrude into the reservoir porosity,in addition the authigenic clay mineral expansion,dispersion and migration to clog the pores' roar and make the coalbed gas reservoir damaged.The relationship between pore size and solid particles was analyzed to consider that the barite and clay particles invaded into reservoir pores was possible when diameter of solid particles less than one-third of the pore.The cores chip identification show that the barite invasion depth is up to 2-3mm even greater distances.Laboratory core swelling and permeability test further proced the possibility of drilling fluid damage the coalbed gas reservoir.On the basis of experiments,two sets revision drilling fluid program were proposed.The first program: KHm-PHP water-based was chemically-modified by adding potassium ionic and nonionic surfactants to achieve the purpose of the reduction of water and soil locks.It was proved by core inflation and permeability experiment.The second program: KHm-PHP water-based drilling fluid was physical modification by adopting the strong magnetic treatment technology magnetization drilling fluid to reduce water and soil locks.Two magnetizer were designed which were respectively inside and outside.Laboratory experiments results show that the drilling fluid can inhibit clay hydration swelling,dispersion,migration and reducing the interfacial tension of filtrate after magnetization.Meanwhile,its rheological properties improved,yield point decline sharp,which reduce the loop resistance to improve drilling speed.