致密碳酸盐岩储层孔喉细小,渗透性差,非均质性严重,微孔微裂缝较为发育,储层易发生应力敏感性损害和水锁损害.结合英买2油田致密碳酸盐岩油气藏特征,系统分析了低渗碳酸盐岩储层的损害特征.评价结果表明,该油田储层应力敏感损害率达82.9％、水锁损害率为72.53％～91.22％是该储层的主要损害类型.在该区原用聚磺钻井液基础上,通过优选高性能处理剂和可有效降低油/水界面张力的表面活性剂,应用理想充填技术,优化设计出了保护储层低损害钻井液；通过开展配伍性、动态污染等实验对该钻井液的储层保护特性进行了评价.实验结果表明,该钻井液具有良好的流变性与配伍性,天然岩心和不锈钢缝板岩心污染实验均表明,优化配方的渗透率恢复值均要高于现用配方,其储层保护效果显著.

Drilling fluid rheological model is a quantitative characterization of rheological properties of drilling fluid,which plays a very important role in hydraulic calculation of drilling operation.In order to investigate rheological model in low temperature and high pressure,a fully automatic rheometer—FannIX77 was used to measure rheological parameters of gas to liquid(GTL) based drilling fluids with two different water oil ratios.The experimental results showed that the shear stress increased with the increase of pressure,and rheological curves didn't pass the base point and the curve slop is ever increasing.The regressed results showed that Bingham model,Casson model and H-B model can reflect rheological properties of the two GTL based drilling fluids under low temperature and high pressure,and power-law model is relatively worse.Casson model has the best matching results compared with Bingham and H-B model.Bingham model is recommended for hydraulics calculation.

The Challenge of drilling fluids in deepwater drilling and the shortage of present rheometer for evaluation of mud′s rheology in deepwater are analyzed.A new fully automatic rheometer,FannIX77 is introduced in evaluating deepwater drilling fluids,and it′s structure,characteristic,technical description and operational models are introduced in detail.This stimulating temperature rang of FannIX77 is from-10℃ to 316℃,and the max pressure is up to 30000 Psi.The instrument is not only suitable for HTHP evaluation,but also has unique advantage in deepwater drilling fluids evaluation.In this paper,we research the rheology of four water-based drilling fluids and synthetic-based drilling fluids under low temperature and high pressure,and discussed it′s application in deepwater drilling fluids.

When operating in deep water,to control the well bore pressure is difficult due to the narrow safety density window.The viscosity and gel strength of drilling fluid are increased with the temperature reduction,and the bottom hole pressure caused by the drilling fluid column in riser is high,so the surge pressures are more difficult to control. This paper highlights the effects of temperature and pressure on rheological properties of synthetic oil based drilling fluids and water base drilling fluids by the ix77 Rheometer made in the company FANN.

低孔低渗储层开发的主要难点为:储层渗透率低、孔隙度小,外来流体侵入后产生敏感性损害及水锁损害,导致毛细管压力大,含水饱和度上升,水锁损害严重;针对低孔低渗储层特征,在PLUS/甲酸钾钻井液体系的基础上,优选了成膜封堵剂,防塌抑制剂UHIB,防水锁剂SATRO,构建了一套适合于南海西部地区低孔低渗储层的钻井作业的钻井液体系。评价结果表明,该体系综合性能良好,抗温达150℃,渗透率恢复值90%以上,滤液界面张力小于2mN/m,具有良好的储层保护效果。