新型防气窜水泥浆在埕岛油田CB306-1井中的应用

A new anti-gas channeling cement slurry used in well CB306-1 of Chengdao oilfield

CB30 6区块在 32 0 0～ 330 0m井段有异常高压气层 ,当量密度高达 1 .38g/cm3 左右 ,固井时该井段水泥胶结较差 ,气窜现象严重 ,固井质量不合格。CB30 6 1井是该区块的第一口开发井 ,为了有效地防止气窜 ,提高固井质量 ,该井固井时采用新型防气窜水泥浆。该体系由SF 1氮气膨胀剂、降失水剂和减阻剂等多种水泥外加剂混拌而成。SF 1氮气膨胀剂呈浅黄色粉末状 ,易溶于水 ,适于水湿混或与水泥干混。在埕岛油田CB30 6 1井的应用表明 ,新型防气窜水泥浆性能稳定 ,膨胀量达到 2 3% ,加强了水泥和地层的胶结 ,并能有效地防止水泥浆失重时高压地层气体的侵入 ,提高了固井质量 ;该体系在常压下有较高的抗压强度 ,对水泥石后期强度影响较小 ;可以湿混或干混 。

There is abnormal high pressure in the 3200～3300 msection of well CB306 1. With its equivalent density as high as about 1.38 g/cm 3 , cementation in this section is poor, gas channeling is serious and cementing quality is deficient. Well CB306 1 is the first exploration well in this block, and in order to inhibit gas channeling effectively and to improve cementation, a new cement slurry with anti gas channeling function was used. This slurry is mixed with a N 2 expansion agent, a filtration reducing agent, a drag reducer and other additives. Field using reveals that the slurry remains stable during cementing job. With the system's expansion reaching 23%, it fills the micro clearance created by volume shrinkage during the cement consolidation progress, strengthensthe gelation between cement and formation, avoids high pressed gas intrusion during weightlessening stage and therefore improves the cement quality. At the same time, the cement system develops higher pressure strength at early stage, which plays little role in later strength development of cement stone. It may be blended in wet or in dry condition, and easy to be used in offshore drilling.