Optimization Of Temporary Plugging Agent For Acid Fracturing Of High Temperature Carbonate Reservoir

Acidification fracturing is an important mode of production for deep high-temperature carbonate reservoirs in the early stage of mining and late stage production.High temperature carbonate reservoirs have high temperature,crack development and serious heterogeneity,and conventional temporary plugging agents are not ideal because of poor temperature resistance and weak blocking ability,which poses great chal enges for temporary plugging in acid fracturing operations,and are not conducive to increasing and stabilizing production of deep high temperature carbonate reservoirs.For this reason,this paper combines theory method with experimental method,proceeds from the characteristics of high temperature carbonate reservoir,investigates the research status of temporary plugging agent at home and abroad,and optimizes the type of temporary plugging agent with good temperature resistance and strong plugging abilit y.The formulation of temporary plugging agent is optimized to form a set of acid fracturing suitable temporary plugging system for high temperature carbonate reservoirs.The results show that:(1)inert temporary plugging agent can not be degraded after acid fracturing operation,and reservoir productivity damage is serious;active temporary plugging agent can be degraded,reservoir protection effect is good,and the solid-free temporary plugging agent has low reservoir damage and good plugging performance;degradable fiber and fuzzy-ball temporary plugging system is selected theoretically.(2)Compared with fibre temporary plugging agent,fuzzy-ball plugging agent system has strong temperature resistance,high plugging strength,good filtration reduction,low reservoir damage and complete degradation.(3)The optimization experiment of the formula of fuzzy-ball showed that the plugging capacity of the fuzzy-ball system increased by 12.32 MPa,the maximum plugging capacity reached 60.51 MPa,and the temperature resistance increased to 160 ? when the airbag agent,the fuzzy agent and high temperature stabilizer was 2.5%,1.0% and 0.9%.The optimum formula of fuzzy-ball was determined to be 2.50% airbag agent + 1.0% fuzzy agent + 0.4% nucleating agent + 0.6% film forming agent + 0.9% temperature stabilizer.(4)Field applicatio n results show that the reservoir fracture sealing capacity is increased by 22.8 MPa and 45.4 MPa respectively during the two injection processes of fuzzy-ball,and the acid fracturing effect is obvious.Practice results show that the plugging effect of the optimized cashmere bag temporary plugging system is feasible and can meet the temporary plugging requirements of acid fracturing operation in high temperature carbonate reservoirs.The plugging effect of the optimized fuzzy-ball has been proved to be feasible and can meet the temporary plugging requirement of acid fracturing operation in high temperature carbonate reservoirs.