油气触发性自密封水泥浆的性能研究

PERFORMANCE OF SELF-SEALING SLURRY SYSTEM TRIGGERED BY OIL AND GAS

油气井水泥环固有的体积收缩可能导致界面胶结强度差,严重时将形成微间隙,发生油气窜。在制备油气触发性膨胀材料(CL)的基础上,开发出油气触发性自密封水泥浆体系。当水泥环的完整性遭到破坏或形成微间隙发生油气窜时,在不中断生产的情况下,水泥环内油气触发性材料被烃类物质触发迅速膨胀,堵塞油气运移通道。室内研究了CL对水泥石力学性能及油气触发条件下膨胀性能的影响,评价了油气触发性自密封水泥浆的高温降失水性能、防窜性能。结果表明,CL水泥石在高温高压油气环境下短时间内有显著的体积膨胀,且在煤油驱替下,其渗透率随时间增加而减小,说明CL水泥石不仅能够密封微间隙窜流通道,且有利于密封水泥石内部窜流通道。油气触发性自密封水泥浆的工程性能及防窜性能均能满足固井技术要求。

The intrinsic shrinkage of cement mantle leads to poor interface cementation strength and form microclearance, and then oil and gas channeling happened. On the basis of preparation of swelling materials triggered by oil and gas(CL), self-sealing slurry system triggered by oil and gas were developed. When cement sheath integrity was destroyed, the materials contained in cement sheath could swell automatically without interruption of production to plug micro-annulus or other flow path, and thus prevents flow of formation fluids through potential leak paths along the annulus. Effects of CL on the mechanical properties and expansion ratio triggered by oil and gas were discussed, the water loss and channeling-control ability of self-sealing slurry system triggered by oil and gas were also evaluated. It showed that CL set cement has large volume expansion ability at high temperature and high pressure oil and gas environment, and its permeability decreased with time increased during kerosene displacement, CL set cement have could not only seal micro-annulus path, but also plug the internal channeling path. The engineering and mechanical properties of slurry system triggered by oil and gas could satisfy the cementing requirements.