氮气膨胀水泥浆防窜固井技术的研究与应用

Research and Application of N2 Expansion Cement in the Prevention of Breakthrough of Gas During Cementing Jobs

固井后的环空窜流会严重影响产能评价、注水效果和油气井产量。对防窜机理进行了探讨。研制开发出了氮气膨胀水泥浆体系,在该水泥浆体系中,氮气膨胀剂由含氮有机物、稳定剂和惰性材料组成,注入井下后,在一定的温度和水泥浆的碱性条件下开始发气。由于稳定剂的作用,氮气形成微小气泡并稳定地存在水泥浆中,形成气体膨胀水泥浆体系。室内评价氮气膨胀剂的常规性能结果表明,氮气膨胀剂的膨胀性能好,与其它水泥添加剂配伍性好,对水泥石抗压强度没有影响。氮气膨胀水泥浆在华北油田、长庆气田和冀东油田等15口井进行了应用,防窜效果明显。

The breakthrough of gas in the annular spaces after cementing has significant negative effects on the evaluation of well productivity,the flood effectiveness and the oil/gas well production.Based on our research on the mechanism of the prevention of the breakthrough of gas,an N2 expansion cement slurry was developed.The N2 expansion initiator is composed of organic nitrogen,stabilizer and an inert substance.Nitrogen will be generated in a basic condition when cement slurry containing the N2 expansion initiator is pumped downhole.The cement slurry and the micro nitrogen bubbles therein form an expansion cement slurry.Lab evaluation of the slurry shows that the nitrogen expansion initiator has a good expansion performance and is compatible with other cement additives.It has no or little,if any,influence on the cement strength.The N2 expansion cement has been successfully applied in 15 wells in the North China,Changqing and Jidong oilfields.