Assessment of Pollution Damage and Study on Reservoir Depth Blockage Removal and Acidification Technology for Reservoirs with Large Leakage of Drilling Fluid

Abstract When extracting oil and gas resources, fractured carbonate reservoirs, due to their good physical properties and well-developed natural fractures and dissolution pores, drilling fluid is prone to significant loss, Caused severe damage to the reservoir. The pollution zone caused by such situations is difficult to effectively penetrate by conventional matrix acidification processes, Seriously affect the oil and gas production of the well. Therefore, for such reservoirs, it is necessary to carry out deep unblocking as much as possible under engineering conditions as possible as a means of reservoir modification. Based on the physical properties of fractured carbonate reservoirs, this paper establishes a drilling fluid leakage model and a pollution skin coefficient calculation model, clarifies the influencing factors of drilling fluid leakage rate and depth, evaluates the degree of pollution damage in reservoirs with different leakage amounts, and forms an acidification design method for large leakage reservoirs with the goal of minimizing the pollution skin coefficient of the reservoir. Combined with field applications, this method has been proven to be scientific and feasible, and has achieved good field testing results.