实用欠平衡钻井钻井液技术

欠平衡钻井钻井液技术是实现欠平衡钻井成败的关键技术之一。针对中国石化新星公司近几年在不同地区施工的30余口欠平衡井所用不同类型的钻井液体系，介绍了低固相聚磺钻井液、无固相盐水聚合物钻井液、低密度乳化柴油钻井液3种钻井液的室内性能评价结果以及现场应用情况，并在此基础上总结分析了各钻井液体系所适用的地层以及其优缺点。无固相盐水聚合物钻井液现场配制简单．成本低廉，特别适用常压碳酸盐岩储层的欠平衡钻井施工，但抗温能力较低．有待于进一步研究；低固相聚磺钻井液是成熟的钻井液体系，适用于水平井以及砂泥岩地层的欠平衡钻井施工；低密度乳化柴油钻井液适用于低压气体欠平衡钻井，但井场安全要求高．成本也相对较高，对油层实施欠平衡钻井，会影响原油的分离，需进一步研究。

Practical drilling fluid technology for under-balanced drilling

Special drilling fluid technology for under-balanced drilling is one of the key technologies for the success of under-balanced drilling. Different types of drilling fluid systems were used in over 30 under-balanced wells by New Star Company of SIN OPEC in recent years, and the low solids polysulfonated drilling fluid, solids free salt-water polymer drilling fluid, and low density emulsified diesel drilling fluid were focused in this paper, with their laboratory evaluation results and field applications described in detail. Based on which, the suitable formations for each drilling fluid system and their advantages and disadvantages were also illustrated. The solids free salt-water polymer drilling fluid is suitable for the under-balanced drilling in the normal pressured carbonate reservoir, as it is easy for field batching and also cost effective; yet its has low temperature tolerance. The low solids polysulfonated drilling fluid is a well-used drilling fluid, and it is suitable for the under-balanced drilling in horizontal well and in the sand and shale formation. The low density emulsified diesel drilling fluid is suitable for the under-balanced drilling in the low pressured gas reservoir, yet its requirements on well site safety are high and the cost is also higher. Apart from the advantages of under-balanced drilling, it can also influence the separation of crude oil and thus need to be further investigated.