复合酸性前置液体系在厄瓜多尔TAMBOCOCHA区块固井中的应用

Application of compound acid pre-liquid system in cementing of TAMBOCOCHA Block in Ecuador

TAMBOCOCHA区块位于厄瓜多尔东部热带雨林地区,储层砂岩孔隙度大,渗透率高,井壁易堆积较厚泥饼,177.8 mm套管封固多个油层且存在油水同层。采用常规前置液体系不能有效清除井壁泥饼,水泥石二界面胶结强度低,固井质量差,容易造成层间窜流影响油井产能效率,缩短油井使用寿命。为此,研发复合酸性前置液体系,体系包含冲洗液、酸性冲洗液、隔离液。酸性冲洗液中盐酸与井壁泥饼中碳酸钙反应,破坏泥饼骨架结构使泥饼松散;3种前置液交替注入有效提高了泥饼清洗效率;用隔离液和先导浆将酸性冲洗液和水泥浆有效隔离,提高了界面胶结质量和封固质量。室内实验表明应用复合酸性前置液体系对泥饼进行清洗,泥饼冲洗效率可达到96%。

The TAMBOCOCHA Block is located in eastern Ecuador's tropical rainforest region.Because of the reservoir sandstone's high permeability and porosity,thick mud cakes are simple to build up on the wellbore.The same layer of oil and water as well as several oil layers are sealed with the 177.8 mm casing string.The mud cake on the well wall can not be removed by using the standard pre-fluid system,and the cementing quality and strength at the cement-stone contact are both substandard.As a result,interlayer channeling is simple to produce,which has an impact on oil well productivity efficiency and shortens their service life.In order to achieve this,a compound acid pre-fluid system is developed that consists of isolating fluid,flushing fluid,and acid flushing fluid.The calcium carbonate in the mud cake on the well wall reacts with the hydrochloric acid in the acidic flushing fluid,destroying the mud cake's skeleton structure and loosening it.The mud cake cleaning efficiency is significantly increased by the alternate injection of three pre-fluids.The spacer fluid and pilot slurry properly separate the cement slurry from the acid-flushing fluid,which enhances the quality of interface cementation and sealing.According to experiment results,the composite acid pre-liquid system can clean the mud cake with an efficiency of 96%.