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针对四川龙岗气田在固井过程中面临的井漏、封固井段长、大温差“超缓凝”、高温高压及高含H2S和CO2酸性气体等难题,根据不同套管层次的固井要求提出了应对策略,通过机理分析和实验对比方法,成功研制了防漏增韧、抗盐大温差及防腐等3种水泥浆体系。室内实验结果表明:不同尺度、不同弹性模量的纤维群具有阻止微裂纹扩展和搭桥成网的作用,可有效解决固井漏失问题;优选的有机酸淀粉类复合缓凝剂SD210及共聚物类抗盐降失水剂SD130可抗高温160℃,防气窜性能好,可解决177.8 mm尾管固井水泥浆超缓凝难题;通过腐蚀前后水泥石抗压强度、渗透率变化对比及X射线衍射(XRD)与扫描电镜法(SEM)分析,证实了通过提高水泥石致密性能实现高效防腐的可行性。龙岗气田现场应用表明,所研制的水泥浆的固井质量得到明显提高,可用于碳酸盐岩酸性气田固井,并能延长气井寿命。
In view of the problems of well leakage, sealing section length, large temperature difference “super retardation ”, high temperature and high pressure, acid gas containing high content of H2S and CO2 in the well cementing process of Longgang Gas Field in Sichuan, Well requirements proposed coping strategies, through the mechanism analysis and experimental comparison methods, successfully developed a leakproof toughening, salt resistance and temperature corrosion and other three kinds of slurry system. The experimental results show that: the fiber groups with different scales and different elastic modulus have the function of preventing microcrack expansion and bridging into the network, which can effectively solve the problem of cementing leakage; the preferred organic acid starch retarder SD210 and copolymer Anti-salt fluid loss agent SD130 can resist high temperature of 160 ℃, anti-gas channeling performance, can solve 177.8 mm tail pipe cementing super-easy coagulation problems; through the corrosion before and after compressive strength of cement, permeability changes and X-ray Diffraction (XRD) and scanning electron microscopy (SEM) analysis confirmed the feasibility of highly efficient anticorrosion by increasing the densification of cementitious materials. The field application of Longgang gas field shows that the cementing quality of cement grout developed has been obviously improved, which can be used for cementing carbonate acid gas fields and prolonging gas well life.