Research On Reservoir Protection Technology Of Wanchang Group In Yitong Basin

The reservoir property of each block in Yitong basin is different,and the early reservoir protection technology pertinence is not strong.This thesis is mainly for the research of protection technology of Wanchang group.Indoor experiment results show that:Wanchang group has low porosity and low permeability.Pore radius which belongs to the capillary porosity is lesser.Clay mineral absolute content is 4.75%,mainly kaolinite.The reservoir has medium to strong water sensitivity and salt sensitivity.The main damage way is water lock damage,followed by water sensitivity and compatibility between drilling fluids filtrate and reservoir and the macromolecular adsorption,the ratio of solid phase damage is smaller.In view of the above research,combined water block resistant technology and film forming drilling fluids technology with shielding temporary plugging technology,the original KCl-polymer drilling fluids system was improved,the types and quantity of waterproof agent and film former were optimized,and according to the D90 method,the composite shielding temporary plugging agent was studied,finally got the optimized drilling fluid,the formula is:4～5%betonies + 0.5%sodium carbonate + 1～1.5%ammonium salt + 0.3%Potassium Polyacrylate KPA +1.5%resistant compound salt fluid loss additive KFH + 0.5～1%KCl +1.5%resistant salt fluid loss agent APC-026 ± 1.5%cationic emulsified asphalt powder YK-Ⅱ + 2%low fluorescence sidewall stabilizer HQ-1+ 0.4%FSJ + 2%CMJ +2%ideal filling complex diversion agent.Research results of indoor experiments show that the optimized drilling fluids can effectively prevent drilling fluid filtrate and solid phase from entering the reservoir,building capacity is good,high temperature stability can meet the requirements of drilling fluid design.Besides,the drilling fluid has good inhibition and compatibility with formation water.After the optimized drilling fluid fouled the core,permeability recovery value could reach 90.14%～92.21%,the purpose of protecting reservoir had been achieved.