保护低压油气藏的钻井液技术研究

Drilling fluid technology for protecting low pressure reservoir

分析了花土沟油田油藏地质特征、岩性及储层物性 ,依据储层敏感性评价结果 ,确定了保护低压油气藏的钻井完井液技术对策及配方 ,即无固相甲酸盐钻井完井液、无(微 )粘土相强抑制性聚合物钻井完井液和微泡沫钻井完井液。现场应用表明 ,3种钻井液性能稳定 ,对地层泥页岩水化分散和吸水膨胀的抑制能力强 ,提高了钻井速度 ,保护油气层效果好 ,满足了钻井施工要求 ,减少了井眼缩径卡钻等复杂情况。用这 3种钻井液钻井与在同等条件下用两性离子聚合物钻井液钻井的产油量 (3.83t/d)相比 ,其产油量平均增加了 0 .2 6～ 1 .74t/d 。

Based on the analysis of Huatugou oilfield's geographic conditions, rock properties and reservoir characteristics and according to the evaluation of reservoir sensitivity, the formulation of drilling/completion fluids technology to protect low pressure reservoir were determined. The fluids include free solid formate drilling fluid, free solid or low solid clay strongly inhibitive polymer drilling fluid and micro foam drilling fluid. Field application showed that the three fluids have good effects on improving ROP and reservoir protection with their stable properties and strong inhibitions to shale's hydrous disintegration and expansion. And by using it, drilling engineering requirements were satisfied and under well accidents such as shrinkage and pipe sticking were prevented. Comparing with zwitterionic polymer drilling fluid by which the oil production is only 3.83 t/d on the same usage condition, the average increment of oil production is 0.26～1.74 t/d.