针对裂缝性地层的低密度高强度韧性水泥浆体系研究

针对鄂南区块产层段延长组由于裂缝发育而导致的固井过程中水泥浆易漏易污染问题，以低密度、防漏、增韧为指导原则，开发低密度高强度韧性水泥浆进行下部产层段的有效封固。通过研发出塑性减轻剂，优选出适合固井用的水性环氧树脂乳液、纳米液硅，提出了环氧树脂-纳米液硅协同增强水泥石性能新方法，研发了密度为1.65 g/cm3环氧树脂-纳米液硅低密度高强度韧性水泥浆。性能测试表明，浆体失水量能控制在40 mL/30 min内，稠化时间具有较合理的时间范围，水泥石具有较高抗压强度，弹性模量不大于7.0 GPa，水泥石具有较好的弹塑力学性能，对储层的污染伤害程度低，实现了低密度、高强度、增韧目标，有利于后期储层压裂改造作业，为鄂南区块古生界天然气勘探开发提供了技术支撑。 

Low-density and Strength Cement Slurry for Fractured Formation

The Yanchang formation in the E’nan block is the naturally fractured pay zone into which losses of cement slurry and hence the contamination of the reservoir often took place. To solve this problem, a low-density high strength high toughness cement slurry was formulated, based on the principle of low density, loss prevention and toughness improvement, to effectively seal the reservoir formation. An innovative epoxy-nanometer liquid silica cement slurry with low density high strength high toughness cement slurry was formulated with the synergy of several additives; a self-developed light-weight agent, a waterborne epoxy emulsion and a nanometer liquid silica that were carefully selected. The density of the cement slurry is 1.65 g/cm3. Performance evaluation of the cement slurry showed that the filter loss of the cement slurry can be controlled within 40 mL/30 min, the thickening time of the cement slurry has reasonable time range. The set cement has high compressive strength, the elastic modulus of the set cement is less than 7.0 GPa. The set cement has good elastic and plastic mechanical properties, and low contamination to the reservoir. Using this technology, low density, high strength and toughness enhancement were achieved. Later stage reservoir fracturing of wells cemented with this cement slurry can be easily performed. The application of this technology has ensured the successful exploration and development of the Paleozoic natural gas in E’nan area.