防塌与保护气层的钻井液技术

Drilling Fluid Technology on Anti-Sloughing and Gas Formation Damage Control

利用X-射线衍射、电镜扫描、岩心流动、表面张力测定等试验,对胜利油田孤北区块中生界及上古生界易塌地层的矿物组构、理化性能以及气层损害主要机理进行了分析。在分析易塌地层井眼失稳与气层损害机理的基础上,依据化学-力学耦合井眼稳定理论,针对易塌地层特点,确定了“强化封固井壁-强化抑制降高温高压滤失-合理密度力学支撑井壁-合理的钻井水力参数”钻井液协同防塌技术。利用优选的高效防塌剂和新研制的气层专用保护剂,开发出了一套防塌与保护气层的钻井完井液体系,并进行了2口井的现场试验。2口试验井均未发生井下复杂情况,与邻井相比,井眼稳定性明显提高,气层保护效果较好,钻井液维护处理较简单,基本形成了一套与地层匹配、防塌、气层保护效果较好的钻井完井液技术。

The extensive lab test studies on the gas formation damage mechanism, physicochemical properties and component/structure of caving ground core in Mesozoic erathem and super Palaeozoic erathem of Gubei area in the Shengli Oilfield have been conducted by means of such laboratory methods as X-rays, SEM, core flooding test, and surface tension measurement, etc. Based on the recognized mechanisms of wellbore instability of caving ground and gas formation damage, the drilling fluid synergic anti-sloughing principle for caving ground is established according to the chemical-mechanical coupling wellbore stability theory. With the optimized anti-sloughing agent and newly prepared gas formation protective agent, the new drilling and completion fluid system is developed and applied in two wells in the Shengli Oilfield. Compared with adjacent wells, the two testing wells have not existed any borehole complex accidents, and have gained good wellbore stability and gas formation protective effect.