四川长宁页岩气速凝水泥浆体系研究与应用

Study and Application of an Quick-Setting Cement Slurry in Cementing Shale Gas Wells in Changning,Sichuan

针对四川页岩气钻进过程中表层易发生失返性漏失,钻井液堵漏效果不佳的情况,研发了液体促凝早强剂ZQ-3、无色无毒液体分散剂ZF-A,形成速凝水泥浆体系。评价了2种外加剂混合液不同加量下速凝水泥浆的性能。实验结果表明,混合液使水泥浆具有良好的流变性能;能显著缩短水泥浆的稠化时间,30℃下混合物加量为3%时,速凝水泥浆与原浆稠化时间之比为0.43;同时显著提高了水泥石早期抗压强度,4 h抗压强度大于3.5 MPa,8 h抗压强度大于8 MPa,表现出优异的低温早强效果。该速凝水泥浆在四川长宁区块页岩气现场应用效果显著,候凝时间由原来的14 h缩短至4-8 h。现场应用7口井,施工24次,全部顺利施工,累计缩短候凝等待时间200 h以上。

Lost return of mud in the top-hole section of shale gas drilling in Sichuan Province were frequently encountered and were difficult to control and stop.A quick-setting cement slurry was developed to deal with this problem.The cement slurry was formulated with a liquid accelerating early strength additive ZQ-3 and a liquid colorless nontoxic dispersant ZF-A.The effect of the mixture of ZQ-3 and ZF-A in cement slurry at different concentrations was evaluated.It was found from the evaluation that the addition of the mixture into a cement slurry helped improve the rheology of the cement slurry.The thickening time was significantly shortened.At 30℃,the ratio of the thickening time of the mixture-treated(3%)cement slurry to the thickening time of the original cement slurry is 0.43.The early strength of the set cement was significantly increased by the treatment of the cement slurry with the mixture of ZQ-3 and ZF-A;the 4-hour compressive strength of the set cement is 3.5 MPa and the 8-hour compressive strength is 8.0 MPa.This quick-setting cement slurry was on 7 shale gas wells for 24 times in block Changning in Sichuan,the wait-on-cement time was reduced from 14 hours to 4-8 hours.All the cementing job was conducted smoothly and total hours of wait-on-cement was reduced by at least 200 hours.