复杂盐膏层定向井固井工艺探讨

Explorati on of Cementing Technology in Complex Salt-gypsum of Directional Well

伊拉克某油田盐膏层定向井的9-5/8″套管固井面临诸多技术难题:定向井段复合盐膏层段长且蠕变压力高,漏失压力当量密度和钻井液密度仅相差0.1 g/cm3左右,极易发生井漏;该井段下部压力系数高达2.25的高压盐水固井期间外窜导致固井质量差、溢流频发及技术套管环空带压;高密度水泥浆配置难度高,可泵性差;固井前循环排量受限,清洗效果差;盐膏层在定向段暴露面积增大,加大了清洗难度;高密度饱和盐水钻井液和高压盐水氯根含量高,与水泥浆接触后,水泥浆存在超缓凝现象。现场通过选用合适的水泥浆体系及加重材料,并采用了双压稳固井技术和其他一系列技术措施,保障了固井作业的安全顺利完工,且固井质量良好。本井的固井作业经验可以为M油田复合盐膏层地层定向井固井及其他类似井的作业提供参考。

The 9-5/8″casing cementing of salt-gypsum directional well in Iraqi oilf ield is faced with many technical problems.Such as the complex salt-gypsum interval in the directional well section is long and the creep pressure is high,the difference between the equivalent circulation density of leakage pressure and the drilling fluid density is only about 0.1 g/cm3,which is easy to leak.The high pressure coeff icient in salt water formation is about 2.25,which is resulted poor cementing quality,kick,high annuls pressure between casing during cementing.High density cement slurry is diff icult to conf igure and poor pumpability.The circulation capacity before cementing is limited and the cleaning effect is poor.The exposure area of the salt gypsum layer in the directional section increases,which increases the diff iculty of cleaning eff iciency.High density saturated brine drilling fluid and high pressure brine have high chlorine content,and the cement slurry has ultra-slow retardation phenomenon after contact with cement slurry.By selecting the appropriate cement slurry system and weighting materials,and adopting the double-pressure well stabilization technology and a series of technical measures,the cementing operation is safely completed and got a very good cementing quality.The cementing experience of this well can provide reference for the cementing operation of this oilf ield complex salt-gypsum formation directional well and other similar wells.