高温高密度水泥浆体系固井胶结面密封性能评价研究

Study on Sealing Performance Evaluation of High Temperature High Density Cement System Cementing Surface

川中地区高温高压气井环空气窜问题严重,水泥浆体系的体积膨胀性对固井胶结面的密封性能至关重要。采用川中地区现场用高温高密度水泥浆体系,开展了高温高压环境下水泥浆体系的体积膨胀性评价实验,采用体积膨胀率与壁面胶结强度衡量胶结面密封性能,提出了固井胶结面密封性能的主控因素,探索了各主控因素对界面密封性能的影响规律。结果表明:水泥浆体积膨胀性与固井胶结面的初始应力变化规律一致,可作为固井胶结面密封性能评价的关键指标之一;环空补偿压力、水泥浆养护温度、膨胀剂加量是水泥浆体系体积膨胀性的3个主控因素;随着环空补偿压力的增大、养护温度升高、膨胀剂加量增大,固井胶结面密封能力增强。研究结果为优选水泥浆体系、优化固井施工工艺提供了理论依据。

Air channeling is a serious problem in high temperature and high pressure gas wells in central Sichuan.Volume expansion of cement slurry system is very important for sealing performance of cementing bond surface.Using the high-temperature and high-density cement slurry system used in the central Sichuan area,the volume expansion evaluation experiment of the cement slurry system under high temperature and high pressure environment was carried out.The volume expansion rate and the wall bonding strength were used to measure the sealing performance of the cemented surface.The main control factors were explored,and the influence rules of each main control factor on the interface sealing performance were analyzed.The results show that:the volumetric swelling of cement slurry was consistent with the initial stress of cementing surface,and can be used as one of the key indexes for sealing performance evaluation of cementing surface;Annulus compensation pressure,cement curing temperature and expansion agent dosage were three main controlling factors of volume expansibility of cement slurry system;With the increase of annulus compensation pressure,curing temperature and expansion agent dosage,the sealing ability of cementing surface was enhanced.The results provide a theoretical basis for optimizing cement slurry system and cementing construction technology.