Research On Improving Deep Well Cementing Quality In QingShen Gas Field

Gas exploration and development of Daqing Oilfield focus on the deep of the north in Songliao basin. According to the ideals of our company that speed up the exploration of natural gas field in Daqing to enhance the transformation rate of deep buried natural gas reservoir, compensate the drop in oil production with natural gas production, emphasize both gas and oil production, the deep and utra-deep wells are increasing year after year. And this brings higher technological demand in deep well drilling. Gas reservoir is primary in deep of Daqing oilfield including Denglouku Formation grit, Yingcheng Formation volcanic rocks. And the most important are volcanic rocks with varied holes and many kinds of fracture. Effected by poor plane connectivity and heterogeneity, we should adopt casing perforation, double stage cementing and cementing to the surface. There are many disadvantage factors such as fracture development, lower fracture pressure, higher geothermal gradient, irregular wellbore, long sealing off section, higher constructing pressure, the stratum containing carbon dioxide which will corrode casing and cement sheath etc. It is claritied that corrosion mechanism of casing and ment sheath by CO2 while an anti-corroding cement slurry system is researched and developed by the experiment; By the study of the result in which annular gas channeling, influence and physical process thoroughly, it is intensively illustrated that the mechanism of annular gas channeling after cementing work. Also a novel gas channeling control slurry system and technology measures are developed which solved the technical problem of high temperature and unstable capability. By tackling key problem, a suit of match technique adapting to cementing in deep of Daqing oilfield is finally formed, which will support the improvement of cementing quality in deep gas well.