Research On Damage Evaluation Method And Protection Of Drilling Fluid In Fractured Tight Sandstone Reservoirs

KeShen6 blocks located in the Tarim basin,KuChe depression crassus thrust belt,is a typical fractured tight sandstone gas reservoir,with dense matrix and micro cracks development two big characteristics.At present,four Wells have been drilled.Due to the damage mechanism and damage degree of the drilling fluid reservoir,it is not enough to understand the comprehensive system,which leads to the poor adaptability of the protection reservoir technology,which restricts the efficient and rapid development of the block.Therefore,it is necessary to carry out the research on the damage of drilling fluid in the fractured tight sandstone reservoir and form corresponding protection measures.The main achievements and recognition are as follows:Clearing KeShen6 block reservoir is characterized by high temperature and high pressure low permeability tight sandstone gas reservoir,poor poroperm correlation,fracture development difference is big,the main crack width distribution around 20 to 50 microns,clay mineral content is higher,is the mainly potential damage factors.Putting forword a new simulation method of artificial crack width and introducing the dynamic damage evaluation device of high temperature and high pressure.The dynamic/static pollution evaluation of drilling fluid is completed.The main damage mechanism of the fractured tight sandstone gas reservoir in block 6 is the matrix phase trap damage and the solid phase blockage of micro fractures.Adding acid soluble of ultrafine ilmenite and rigid aluminum alloy particles GYD temporary plugging material,compound mud cake remover,The optimized formula of drilling fluid,acid soluble temporary plugging scheme and supporting oil-based mud cake remover are developed.