RESEARCH AND APPLICATION OF DEEP ACID FRACTURING TECHNIQUE IN SPECIAL CRETACEOUS RESERVOIR OF YUMEN OILFIELD

The lithology of Cretaceous Xiagou Formation reservoir in Qingxi long term production block of Yumen Oilfield is particular:terrigenous elastic rock takes 35.16%,carbonate rock 33.84% and clay mineral 31.01%.The permeability is low,porosity is low,and the natural fractures are developed.The average depth of the middle reservoir is 4200 m,the average temperature is 120℃.For the particular lithologic reservoir,through analysis of slice appraisal,X-diffraction,scanning electron microscope and so on,combining them with the research results like acid etching diversion capacity simulation test,reservoir numeric simulation and optimized design,this paper presents a particular stimulation process-deep acid fracturing with friction reducing acid plus closed acidizing with multi-component acid.This paper also presents the liquid sys-tern suitable for reservoir reforming.Field application of this process in well Liu102 shows that the stimulation effect is obvious:oil is increased by 102 t per day,and the multiple of incremental oil recovery is 10.