Study On Damage Law Of Drilling Fluid And Fracturing Fluid In Fractured Tight Sandstone Reservoir

Keshen and Dabei tight gas reservoir are characterized by deep burial depth,low porosity,low permeability,fracture development and strong heterogeneity,which were developed mainly with reservoir stimulation technique at present.For the above reasons,Keshen and Dabei gas reservoir were also described by fractured tight sandstone reservoir and the formation was easily to be damaged by the drilling fluid and stimulation fluid in the process of drilling and reservoir stimulation.The damage of working fluid on the formation could increase the percolation resistance,which would affect the rate of oil and gas and the final recovery.Compared to the storage-permeation characteristics and the damage law of working fluid for conventional sandstone reservoir,fractured tight sandstone reservoir had its own special characteristic.Therefore,it was vital to study the damage law of drilling and working fluid for fractured tight sandstone reservoir.Aimed at solving above problems,the measurement model of matrix permeability for tight reservoir had been established when taking the fractured tight sandstone reservoir of Bashijiqike Formation,Keshen gas reservoir as the research objects.With the above model and relevant developed equipment,the damage degree and law of oil-based drilling fluid and fracturing fluid on tight sandstone reservoir had been measured.The above damage degree and law of oil-based drilling fluid and stimulation fluid on fractured tight sandstone reservoir had been measured with the artificial fractured core,which was made by setting the same width as the natural fracture to simulate the natural core with fracture.The above research results have guidance significance to the research and development of new low-damage working fluid and the optimization of reservoir formation protection measures.