摘要
水力加砂压裂既是气藏增产改造的主要措施,同样也会对地层造成损害,这种损害较钻井、完井过程的损害更易被忽视,特别是低渗致密气藏在压裂增产中地层损害现象及其影响尤为严重。岩心流动实验证明,川西侏罗系气藏储层属于低渗致密敏感性砂岩储层,除碱敏相对较弱外,其水敏、速敏和应力敏感属强-极强敏感损害,是压裂增产措施中潜在的损害因素。目前现场使用的压裂液对川西地区储层和支撑充填层均存在损害,损害原因除地层潜在的敏感损害因素外,还与压裂液残渣形成的滤饼,未完全破胶的有机胶团以及滤液滞留地层引起的“水锁”损害等有关。“水锁”是造成川西侏罗系低渗气层损害的主要原因之一。使用压裂液助排剂技术和压裂液损害解堵技术,能有效降低和解除由此而引发的地层损害。
Hydraulic sand fracturing is a major measure for gas reservoirs to increase production. Meanwhile, it will damage the formations. The damage is omitted more easily than that caused by drilling and completion operation. Furthermore, the formation damage and its influence by fracturing stimulation are more severe for low-permeable tight gas reservoirs. The flow experiments of cores show the Jurassic gas reservoirs in west Sichuan belong to the lowpermeable, tight and sensitive sand gas reservoirs. Except the alkali-sensitivity is relatively poor, the water-sensitivity, flow-rate-sensitivity and stress-sensitivity are all strong, even super-strong, which are the potential factors leading the formation damage in fracturing process. The fracturing fluids used recently in the fields will damage the reservoirs and the filling beds in the west Sichuan area. Besides the potential sensitivity damage, it will lead damage the filter cake formed by the fracturing fluid residues, the un-breaking organic gel group, and 'water lock' caused by the residual fluid etc. The 'water lock' is one of the main reasons leading the formation damage of Jurassic low-permeable gas reservoirs in west Sichuan. With the techniques of the cleanup additive and blocking remover of fracturing fluids, the formation damage can be reduced or eliminated effectively.
出处
《天然气工业》
EI
CAS
CSCD
北大核心
2005年第7期86-88,共3页
Natural Gas Industry
