深井低密度耐高温水泥基固井材料制备及性能研究

Preparation and performance study of low density and high temperature resistant cementitious materials for deep wells

摘要:

在深层油气井固井过程中极易发生浆液漏失事故，井内较高的温度往往会导致固井材料的性能发生退化。以G级油井水泥为原材料，超细粉煤灰、玻璃微珠、纳米SiO2为辅助填料，通过正交试验和熵权法得到了深井低密度耐高温固井材料配方：85%水+100%G级油井水泥+10%超细粉煤灰+15%玻璃微珠 +7%纳米SiO2+2%降失水剂+2%稳定剂+1%早强剂+1%缓凝剂+0.5%增塑剂。在此基础上，通过室内测试、扫描电镜、X射线衍射等方法研究了该材料的常规物理性能、耐高温性能及微观结构。结果发现，浆液密度为1.42 g/cm3，相较于G级油井水泥（1.87 g/cm3）降低了24%。水泥石抗压强度随温度升高先增大后趋于稳定，当温度从20 ℃升高到160 ℃时抗压强度增大了31.11%，其耐高温性能相较于G级油井水泥更加优异。在160 ℃下的微观结构比较致密，水化程度高，有大量的硅质胶结物填充。研究成果可为深部油气开采和相似固井材料的研发提供一定的技术参考。

Abstract:

Slurry leakage accidents are highly likely to occur in the cementing process of deep oil and gas wells, and higher temperatures in the wells often lead to degradation in the performance of cementing materials. Using G-grade oil well cement as raw material and ultrafine fly ash, glass microsphere and nano SiO2 as auxiliary fillers, the formulation of deep well low density high temperature resistant cementing material was obtained by orthogonal test and entropy weight method: 85% water + 100% G-grade oil well cement+ 10% ultrafine fly ash + 15% glass microsphere + 7% nano SiO2 + 2% fluid loss additive + 2% stabilizer + 1% early strength agent + 1% retarder + 0.5% plasticizer. On this basis, the conventional physical properties, high temperature resistance and microstructure of HTRC were investigated by indoor tests, scanning electron microscope and X-ray diffraction. It was found that the density of the material was 1.42 g/cm3, which was 24% lower than that of G-grade oil well cement (1.87 g/cm3). Its compressive strength increased with temperature and then stabilized, and increased by 31.11% when the temperature increased from 20 ℃ to 160 ℃, and its high temperature resistance was more excellent than that of G-grade oil well cement. The microstructure at 160 ℃ is relatively dense and highly hydrated, with a large amount of siliceous cements filling. The results can provide some technical references for deep oil and gas extraction and the development of similar cementing materials.