大庆调整井防漏水泥浆的研究

大庆喇、萨、杏油田,由于长期注水开发,造成局部注采不平衡,地层压力发生了很大变化,形成在1口井中同时存在高压层和欠压层的复杂地质条件,在钻井和固井过程中极易发生井漏。调整井防漏水泥浆技术,从减阻入手,利用外加剂改善水泥浆的流变性能和封固性能。室内做了5个方面的试验:1.常规物理性能;2.流变性能;3.膨胀及界面强度;4.自由水;5.抗水窜性能。试验表明:DFL外加剂水泥浆各项指标优于未加外加剂的水泥浆。并得出:1.DFL低摩阻防漏水泥浆具有良好的流变性能,临界排量低,容易实现低速紊流顶管,在同等条件下,摩阻比原浆低74%,现场替浆泵压降低1MPa。2.DFL低摩阻防漏水泥浆体系稳定,无自由水析出。3.抗压强度与界面强度比原浆都有所提高,并有一定的膨胀和抗窜性能。4.外加剂加量少,且全部采用湿混形式,易在现场应用。

RESEARCH ON ANTILEAKAGE CEMENT SLURRY FOR ADJUSTMENT WELLS IN DAQING OILFIELD

Great changes occurred in formation pressure because of long-term waterflooding in La, Sa and Xin oilfield of Daqing. So high-pressure zone and under-pressure zone exist in one well simultaneously, as a result, lost circulation is very easy to occur during drilling and cementing. Antileakage cement slurry technology for adjustment well can improve rheological and cementing performance by using additives. Experiment in 5 aspects were carried out: 1. Conventional physical performance; 2. Rheological performance; 3.Expansion and interface strength; 4. Free water; 5. Anti - water breakthrough performanc e. The experiment showed: the indexes of DFL cement slurry were better than those of cement slurry without additives. And concluded: 1. DFL antileakage cement slurry with low frictionaI resistance had good rheological performance and low critical flow rate. Low-speed turbulent flow displacement was easy to be obtained. Under the same condition, the frictional resistance was 74% lower than that of the original slurry, the pumping pressure of displacement on-site can be decreased by 1MPa. 2. DFL cement slurry was stable and no free water separated out. 3. The compression strength and interface strength are increased than before, the cement slurry had a certain expansion and anti - water breakthrough performanc e. 4. A little additives were required and wet mixing was adopted, so it was easy to be used on site.