枯竭油气藏型储气库钻完井技术研究与应用

Research and Application of Drilling and Well Completion Technology of Underground Gas Storage of Depleted Oil-gas Reservoir

辽河双6块目前已接近枯竭,该区块改建地下储气库,固井质量是钻完井施工的核心。钻完井施工的难点主要包括储层压力系数低,建库技术要求较高,国内可借鉴的经验少,对注采井井筒的完整性要求高,缺乏必要的完井工具及配套技术等。针对于此,根据钻遇地层的特点及时调整钻井液性能和密度,并进行随钻堵漏和承压堵漏,平均每口井承压堵漏3～4次,承压能力由最初的1MPa提高到5.5～6.5MPa;技术套管固井时采用连续分级注水泥固井工艺,减小了水泥浆液柱压力;应用高强低密度水泥浆降低静液柱压力,盖层段固井应用胶乳水泥浆以增强防气窜能力;为保证井筒的密封性和完整性,技术套管和油层套管选用气密封套管,并逐根进行气密封检测。储气库钻完井的特殊工具和技术服务主要依靠国外石油公司,钻完井成本高,应进一步研发性能可靠的特殊工具。

Shuang6 block in Liaohe oilfield is a depleted oil-gas reservoir.Underground gas storage was built in this block.Cementing quality is the heart of drilling and well completion.Difficulties of the drilling and well completion are： low reservoir pressure coefficient,strict technical requirement,few experiences in China,needing exact injection-production hole integrality and lacking of necessary well completion tools and supported techniques.So,performance and density of the drilling fluid should be adjusted in time according to the features of the drilled formations.Mud loss control while drilling and under pressure should be done with three or four times for each well and pressurization capacity enhanced from 1MPa to 5.5-6.5MPa.When cementing by protective casing,continuous multistage cementing is adopted to reduce cement column pressure.Cement slurry with high intensity and low density may be applied to reducing hydrostatic column pressure.Latex cement slurry may be applied to cementing in the cap rocks for better gas block capacity.The protective casing and production string should be gas tight and tested one by one so as to ensure sealing property and integrality of the bore hole.Special tools and technical service of the drilling and well completion for the gas storage come from foreign oil company,so the drilling cost is high.The special tools with good performance should be developed.