热采井固井水泥无氯促凝剂CN-1作用机理研究

Study on the Effect and Mechanism of non-Chlorine Coagulant in Heavy Crude Oil Thermal Wells Cementing

稠油热采井固井用含氯促凝剂对水泥石有明显促凝和低温早强作用,但高温热采作业时,水泥石抗压强度由高温前50℃养护下的20.58 MPa衰退至高温315℃养护下的1.59 MPa,水泥石抗压强度衰退较为严重。本文评价了无氯促凝剂CN-1对加砂水泥石早期抗压强度和高温前后抗压强度的影响,通过X-射线衍射仪测定了高温前后水化产物组份,并结合电镜扫描观察水化产物形貌变化分析了无氯促凝剂对水泥石早期抗压强度和高温性能的作用机理。实验结果表明,在315℃高温养护下,加3%无氯促凝剂CN-1的水泥石抗压强度为20.21MPa,CN-1参与了水泥高温水化反应,促使高温下生成更多以针状纤维交叉堆积的硬硅钙石。水泥石具有较高的抗压强度,有效防止了水泥石高温后抗压强度衰退现象。

The chlorine coagulant used in thermal recovery cementation can accelerate coagulation and early strength of cement. However, the compressive strength of set cement declines severely during high-temperature thermal recovery operations. When cured under 315℃, the compressive strength of cement paste decreased from 20.58 MPa （50℃） to 1.59 MPa. In this paper, the effects of non-chlorine coagulant CN-1 on the early compressive strength and the high temperature compressive strength of cement with silica sand was evaluated, the structure of hydrate component before and after high temperature was measured by means of XRD and SEM, the functional mechanism of non-chlorine coagulant on cement paste＇ s early compressive strength and high temperature properties was probed. The results indicated that when adding 3% non-chlorine coagulant CN-1, the compressive strength of cement paste was 20.21 MPa under curing at 315℃, and CN-1 participated in the high temperature hydration reaction, which formed more xonotlite like cross- stacked raphidine. As a result, a high compressive strength of cement paste was maintained and the decline of compressive strength after high temperature curing effectively was prevented by adding CN-1.