强抑制性KCl/硅酸盐钻井液体系及其在苏丹六区的应用

为解决苏丹六区Abu Gabra层在钻井过程中出现的严重井壁失稳问题,在对坍塌层位岩样进行综合分析的基础上,通过室内实验,研制出一种KCl/硅酸盐钻井液体系.该体系的特点是组成简单,硅酸盐的模数适中,具有较高的pH值,抑制岩屑水化膨胀能力强.硅酸盐稳定井壁的实质是一种化学封堵、固结作用,而沥青类、聚合醇类封堵型井壁稳定剂主要是通过物理作用来达到稳定井壁的目的,因而抑制能力相对较弱.另外,硅酸钠对环境无影响、无荧光、使用温度范围宽、价格较其它两类处理剂低.介绍了该体系在Moga-8井和FN-29井的应用情况.现场应用结果表明,该体系满足了苏丹六区的钻井施工要求,收到了良好的应用效果.

Strong inhibitive KCl/Silicate based drilling fluid and its application in Sudan Block6

In order to minimize the severe wellbore failure of Abu-Gabra formation in Sudan Block6, a KCl/silicate based drilling fluid was developed on basis of comprehensive analysis of rock samples collected from cavy formation and a lot of laboratory experiments. The characteristics of this drilling fluid are simple composition, proper modulus of the selected silicate, higher pH value and strong cuttings inhibition. Different from plugging wellbore stabilizers such as asphalt materials and polyalcohol, the wellbore stabilizing mechanism of silicate is chemical sealing and cementing action, while the latter approaches this target just by physical action, resulting in their relative weaker inhibiting ability. In addition, silicate has advantages including environmentally acceptance, non-fluorescence, wide temperature window and economical preponderance to the other two stabilizing agents. Case study of Moga-8 well and FN-29 well were described in detail in this paper. All the data onsite showed that KCl/silicate based drilling fluid fulfilled the requirements of drilling operations in Sudan Block6.