Analysis of Reservoir Sensitivity and Optimization of Drilling Fluid System in Block H9 of Tarim Oilfield

针对塔里木油田H9区块钻井过程中存在的储层损害问题,采用黏土矿物分析、扫描电镜及压汞法等方法,分析掌握了目标区块储层地质特征,并结合储层敏感性试验评价,明确了储层潜在敏感性损害因素,揭示了储层损害机理。结果表明,H9区块储层黏土矿物含量为10%~20%,具有中高孔渗特征,非均质性较好,且存在潜在的强速敏和强水敏性损害。针对现场用钻井液体系存在的抑制性、润滑性及储层保护效果存在的不足,室内优化了一套综合性能优良的KCl-聚合醇储层保护钻井液体系。通过模拟储层动态损害试验评价可知,储层岩心渗透率恢复值可达85%以上。现场试验结果表明,KCl-聚合醇钻井液体系可较好地抑制泥页岩水化膨胀分散,有效避免了井眼缩径、起下钻遇阻等井下复杂情况发生,保障了钻井施工高效、安全,且储层保护效果良好。

In allusion to the problem of formation damage in drilling of Block H9 in Tarim Oilfield, various methods including clay mineral analysis, SEM and mercury intrusion were used for analyzing the geological characteristics in the target zone, and combined with the evaluation of reservoir sensi- tivity test, the potential sensitivity damage factors and damage mechanism were determined. Re- suits show that the clay mineral content is 10%o to 20% in the block. It has the feature of middle- high porosity and permeability with obvious heterogeneous and there potentially exist strong ve- locity and water sensitivities, in consideration of the inhibition and lubrication property in the drilling fluid system and poor effect of formation protection, a set of good performance KCl-po- lyalcohoi drilling fluid system is optimized in laboratory. It is known in the dynamic test on re- servoir simulation that the core permeability recovery value can be up to 85%. Field test result shows that KCl-polyalcohol drilling fluid system can be used for better control of shale hydration and expansion, effective avoiding the downhole complexity such as hole shrinkage stuck in trip- ping~ it ensures a high efficient and safe well drilling and a good formation protection effect is ob- tained.