耐交变超高温固井水泥浆

A Cementing Slurry Used in Alternating Ultra-High Temperatures

在稠油热采井中,交变超高温将对固井水泥石的力学性能造成巨大影响。为研制抗高温能力强的水泥浆体系,基于XRD、TG、氮吸附及SEM方法,研究了交变超高温下偏高岭土和石墨对水泥石抗压强度、水化产物化学结构及微观结构的影响。研究结果表明,交变超高温可使常规加砂水泥石C—S—H的形态由“链状”或“网状”转变为“颗粒状”,破坏水泥石的结构完整性,从而降低其抗压强度;掺入偏高岭土和石墨后,可提高常规加砂水泥石耐交变超高温能力,且对水泥石物相组成影响不大;偏高岭土有颗粒填充作用和火山灰效应,且石墨与水泥基体界面胶结良好,使其二维方向上起到拔出作用,提高了水泥石结构完整性及力学性能。该研究结果可为稠油热采井固井水泥浆体系的性能评价及配方优化提供参考。

Alternating ultra-high temperatures in heavy oil thermal producers have significant effects on the mechanical performance of set cement.In developing a high temperature cement slurry,XRD,TG nitrogen adsorption and SEM were used to study the effects of metakaolin and graphite on the compressive strength of set cement,the chemical structure and micro-structure of the hydration products of the cement under alternating ultra-high temperatures.The study showed that alternating ultra-high temperature can change the pattern of the C-S-H bonds of a sand-contained set cement from“chain”or“network”to“particle”,thereby damaging the structure integrity and reducing the compressive strength of the set cement.After blended with metakaolin and graphite,the set sand-contained set cement has its ability to resist alternating ultra-high temperature improved,and the metakaolin and graphite have only minor effects on the phase composition of the set cement.The metakaolin has particle filling effect and volcanic ash effect,the graphite has good bonding with the cement body;these two factors help enhance the structural integrity and mechanical property of the set cement in two dimensions.All these research findings have provided references to the performance evaluation and composition optimization of cement slurries for heavy oil thermal producers.