Study On Cementing Technology Of Long Sealing Section Of Gas Storage In Huabei Oilfield

Suqiao Gas Storage is the first gas storage reservoir in Huabei Oilfield,which is responsible for the energy structure optimization of Beijing-Tianjin-Hebei.It is operated to meet the gas peak shaving demand of the Beijing in winter and promote the development of clean and low-carbon energy in North China,presenting great strategic significance.Cementing quality is the core of gas storage well construction.Specific standard and specifications for the cementing quality of the formation cap section and that of the production casing.Cementing operations in Suqiao Gas Storage are facing the challenges of deep depth,complex lithology,narrow pressure window,serious depleted reservoir and high formation temperature.To address the above issues of cementing,cementing technology for long section has been studied.After the challenges and problems of cementing of the gas storage in Huabei Oilfield were analyzed,main studies have been focused on the optimization of cement slurry of main sealing section,high efficient flushing spacer system and supporting techniques for long sealing section cementing.According to the research work,DRE flexible expansion cement slurry system and large temperature difference long sealing section cement slurry system were selected.Compared to the previous cement slurry,the DRE flexible expansion cement slurry system has a 47.9% reduction in elasticity modulus with value of 5.3 GPa.Composite retarder and cement slurry system with the temperature rating of 110??140?and temperature difference capacity of 70? were also selected based on the requirement of cementing of the gas storage in Huabei Oilfield.The previous inferior spacer for deep well long cementing section resulted in poor flushing and isolation performance and consequent cementing problem.To address the problem,suspending agent,detergent and prismatic materials were used to develop a high-efficiency flushing spacer system,which has a doubled flushing efficient that can allow large displacement pumping and improve the displacement efficiency and cementing quality.For the requirement of single stage cementing operation to ensure wellbore integrity for later operation,the “three densities and four thickening time slurries” balanced pressure cementing technology was developed.The single stage cementing ensured the wellbore integrity and has addressed the ultra-long section cementing problem.The research work has been successfully applied in more than 30 wells with “good”cement quality.The Well 9-11 X pilot test well,which has a single stage length of 4709 m,was successfully cemented with “good” cap section cementing quality and 71 m continuous“good” cementing quality,setting a new record of the longest single stage cementing section of Huabei Oilfield.The researches provided a feasible method for the cementing of depleted gas storage reservoir in Huabei Oilfield.