Research On Reservoir Geological Characteristics And Fracturing Fluid Damage Mechanism Of Shahejie Formation In G94 Fault Block Of Jidong Oilfield

For reason that natural productivity of low permeability oil-gas reservoir is bad,it has to make fracturing stimulation measures to obtain the economic value.Hydraulic fracturing has become essential technical means to improve mining efficiency and develop to ultra-low permeability reservoir.Fracturing operations can improve conductivity of reservoir and improve oil and gas path,on the other hand,fracturing fluid would do harm for the reservoir after enter into the ground.Therefore,to avoid reservoir damage that fracturing fluids caused,is important for low permeability oil-gas reservoir development.As the research object in Paper,low permeability reservoir of Jidong oilfield G94 fault block shahejie formation,it is not has explicit geological characteristics knowledge and have some issues that exposed during the production process,such as low productivity hydro fracturing stimulation effect is not obvious and reservoir contaminated by fracturing fluid.The paper intensive studies geological characteristics of reservoirs and confirm potential damage factor of.Reservoir.On the basis of the existing evaluation methods,the paper improved fracturing fluid damage evaluation method to quantitative evaluate damage that single of factors fracturing fluid caused.The paper determined major damage mechanism of fracturing fluid,provide the gist for designs of fracturing fluid.Research Findings:(1)The main reservoir of G94 block of jidong oilfield is the second and third member of shahejie formation,belonging to fan-delta system,Reservoir rocks is mainly composed by medium to fine grained lithic arkosic.Interstitial content is 5%on average,dominated by clay minerals,clay minerals dominated by XI and chlorite.Pore types of the reservoir rock is mainly composed by in primary intergranular pores and secondary intergranular pore and pore throat structure is middle pore thin throat.The average porosity of the reservoir rock was 15.1%and the permeability is 21.6 mD.Physical property is poor,belonging to low permeability reservoir.(2)G94 fault-block reservoirs in jidong oilfield speed sensitivity extent of damage is medium to strong,water damage is medium to strong,acid-sensitive damage is weak;alkali sensitivity damage is medium to strong,salt sensitivity damage is medium to weak.(3)We make the guar gum of fracturing fluid system and clean fracturing fluid system to breaks down at 120 ? and 2H and find gelout effect is good.the filtration coefficient of guar gum fracturing fluid is smaller than clean fracturing fluid.(4)The thesis improved the experimental method and Classify divided the damage factors of fracturing fluids into thickeners,the reaction damage of fracturing fluid and sensitive mineral and water locking damage.The thickener damage of fracturing fluid was subdivided into superficial,deep and additional damage.The thesis quantitatively evaluate the damage that fracturing fluid reservoir single factor caused and explicit the main damage factors.The studies have shown that the main damage of fracturing fluid reservoir is thickener damage,the reaction damage of fracturing fluid and sensitive mineral and water locking damage is weak,belonging to minor damage.The damage that the intrusion of solid phase particles and the polymer adsorption is accounted for the major part in thickener damage and additional damage that polymers caused is weak.