新型低固相油基钻井液研制及性能评价

为解决常规油基钻井液低温流变性差、低剪切速率下易形成凝胶结构及重晶石沉降等难题,开展了低固相油基钻井液的研究。选用3~#白油为基础油,甲酸铯溶液为密度调节剂,在确定油水比的前提下,对各主处理剂进行优选及加量确定,研制出一种低固相油基钻井液体系,并对其抗温、抗污染、抑制性及储层保护效果等性能进行了评价。评价结果表明,低固相油基钻井液体系具有良好的流变性和触变性,抗温达220℃,抗水污染20%,抗钻屑污染25%,滚动回收率98.7%,渗透率恢复值90%以上。分析认为,低固相油基钻井液体系不仅能够代替常规油基钻井液应用到强水敏地层及复杂结构井,在裂缝性碳酸盐及低孔低渗储层也具有良好的应用前景。

Development and performance evaluation of new low-solid oil-based drilling fluid

The conventional oil-based drilling fluid has many problems,such as poor rheology,being easy to form strong gel structure at low shear rate and barite settlement.In order to solve these puzzles,a low-solid oil-based drilling fluid technology was carried out.With 3# white oil as base oil,cesium formate solution as density modifier,reasonable oil/water ratio,main treatment agents optimization and added amount,a low-solid oil-based drilling fluid system was developed.The temperature resistance,contamination resistance,inhibition and formation protection were evaluated.The novel mud has good rheology,thixotropic,temperature resistance(up to 220 ℃),strong inhibition(98.7％ scroll recovery) and excellent contamination resistance(20％ water tolerance and 25％ cuttings tolerance),and it can also effectively protect reservoir and achieve more than 90％ of permeability recovery.Analysis shows that the new mud system not only can be applied to strong water sensitive formation and complex structure wells instead of conventional oil-based drilling fluid,but also has good prospect in fractured carbonate and low porosity and permeability reservoirs.