Grey Assessment Method of Lost Circulation Risk and Application in Yuanba Gas Field

According to the strong uncertainty and vagueness of lost circulation in ultra-deep gas wells,the analytical hierarchy process and grey analytical method are applied to assess the risk of lost circulation.On the base of risk index weight determined by analytical hierarchy process,the grey analytical method and drilling engineering are combined to build up a lost circulation forecast model,which forms a set of quantitative assessment method of lost circulation risk in drilling process.This method is applied in well Yuanba122,and the application result shows that it can forecast lost circulation effectively.