Abstract: Lamadian oilfield has the characteristics of high clay mineral and serious reservoir sensitivity. In addition, limited by the heavy weight additive, the completion fluid can not meet the requirement of blowout during the process of perforating completion operation due to formation high pressure. Through single agent screening and laboratory research of formation compatibility, the optimal well completion fluid for polymer flooding and new production wells has been provided, which can guarantee stable and high production of new production wells. The research results indicate the well completion fluid has good compatibility with formation, the dynamic permeability recovery of reservoir rock was more than 80%, the optimal well completion fluid formula is DFW-1 type completion fluid base fluid+1.0% WY type clay stabilizer solution + salt crystallization inhibitor (with NaNO3 as heavy weight additive) +1.0% corrosion inhibitor.