无固相清洗型隔离液研究与应用

针对隔离液中的固相会对井下裸眼段和渗透率较高的砂岩等主要油层段造成污染,开发了一种无固相的清洗型固井隔离液,并对隔离液的综合性能进行评价。实验结果表明,无固相隔离液密度在1.00~1.80 g/cm3之间可调;隔离液在180℃下养护后上下密度差为0,未出现高温沉降现象,具有良好的抗温性能;隔离液的塑性黏度小于6 mPa·s,屈服值为0 Pa,为牛顿流体,易实现紊流顶替;有机盐钻井液、抗盐水泥浆与隔离液以不同比例混合后,流性指数值增加,稠度系数值降低,说明隔离液与有机盐钻井液和抗盐水泥浆具有良好的相容性;隔离液与不同比例抗盐水泥浆混合后,混浆的稠化时间变长,能够确保施工安全。隔离液对井壁上的虚泥饼及油污等的清洗效率在90%以上,有利于形成提高水泥胶结质量的水湿环境,提高固井质量。无固相隔离液在伊拉克市场现场应用29井次,应用效果良好,有效地解决了高压盐膏层固井难题。 

Study and Application of Solids-free Flushing Spacer

A solids-free flushing spacer was developed for use in drilling operation to prevent open holes and high permeability sandstones from being damaged by the solids in spacers. In laboratory experiments, the density of the spacer can be adjusted between 1.00 g/cm3 and 1.80 g/cm3. No density difference was found of the top and the bottom of the spacer after aging at 180℃, indicating that no sedimentation ever occurred. The spacer was a Newtonian fluid, having plastic viscosity of 6 mPa·s and yield value of 0, meaning that turbulent flow displacement can be easily realized. When contaminated with a mixture of organic salt drilling fluid and salt-resistant cement slurry, the flow index of the spacer increased, while the consistency factor decreased, meaning that the spacer was compatible with organic salt drilling fluid and salt-resistant cement slurry. When mixed with saltwater at different ratios, thickening time of the mixture was prolonged, which is beneficial to safe operations. 90% or more pseudo mud cakes and oil dirt on the borehole wall can be flushed away, which is beneficial to the development of bonding strength between cement sheath and borehole wall. This solids-free spacer has been used 29 times in Iraq, successfully solving problems encountered in cementing high temperature wells, and wells with salt and gypsum formations.