Compared with conventional well,deepwater and ultra-deepwater well had narrower safety density window of drilling fluid,which gave stringent technical requirements for drilling fluids. Aiming at this problem,the effects of low density agent LDA60 and water-soluble pressure plugging agent PF-STRH on the density,rheology and pressure bearing of drilling fluid were studied,the advantage and disadvantage of full-hydrate scheme and half-hydrate scheme inhibition were compared. Finally,PF-STRH and hydrate control technology were applied on deepwater well LS25-1-S1 with high temperature and pressure and ultra-deep well LS18-1-1 in South China Sea. The results showed that LDA60 could effectively reduce the density and had little effect on the rheology of drilling fluid. The pressure bearing capacity of HEM drilling fluid could be improved by 2 times after adding 3% PF-STRH,indicating good effect. Half-hydrate scheme was recommended during deepwater drilling operation considering the cost and environment. After pressure plugging and hydrate inhibition operation,the density of drilling fluid reduced and pressure bearing improved with no influence on rheology. PF-STRH and hydrate control technology could be used in the drilling of deep water and ultra-deep water wells with narrow density window.
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李怀科,张 伟,马 跃.深水窄密度窗口钻井液技术改进及现场应用[J].油田化学,2018,35(2):209-213. LI Huaike, ZHANG Wei, MA Yue. Technology Improvement and Field Application of Deep Water Drilling Fluid for Narrow Drilling Window[J]. OILFIELD CHEMISTRY,2018,35(2):209-213.