低温短候凝水泥浆体系室内研究

Laboratory Study on the Cement Slurry System with Short Waiting on Cement Time at Low Temperature

在导管、表层套管固井中,由于地层温度较低,油井水泥强度发展缓慢,候凝时间长,增加了钻井成本,并易造成环空窜流,影响固井质量和作业安全。针对目前国内油井水泥早强剂种类少、某些油井水泥早强剂存在早强效果不佳以及对水泥浆流变性影响较大等问题,通过室内试验筛选出一种新型的无氯、含晶种复合型早强剂SW-Z1,从而形成了一套密度1.30～1.90kg/L的低温短候凝水泥浆体系。低温短候凝水泥浆体系的室内性能评价试验结果表明,该水泥浆体系具有直角稠化、低温候凝时间短、早期强度高、流变性能好,防气窜能力强等优点,可满足不同地层压力条件下的低温浅井固井需求。

In the cementing of conductor and surface casing,cement slurry has long waiting on cement（WOC） time due to the low bottom hole circulating temperature（BHCT）,the slowly increasing compressive strength of cement,the drilling cost has been increased,the annular gas channeling would occur,which impairs cementing quality and operation safety.In view of the fact that there are few types of early strength agents currently at home,some early strength agents have poor effectiveness and significant negative impact on slurry rheology etc,a new compound early strength agent with no chlorine and containing crystal seed was selected by laboratory tests.The thickening time,compressive strength,rheologic properties,anti-gas channeling ability and other parameters of the slurry have been tested.The results showed that the cement slurry has such advantages as right-angle setting behavior,short WOC time at low temperature,high early strength,good rheologic properties,strong ability of anti-gas channeling,etc.The low density cement slurry ranged from 1.30 to 1.90 g/cm^3,provides a reliable and safe cementing operation in shallow wells at low-temperature and different reservoir pressures.