科研之友
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摘要
The Quaternary unconsolidated sandstone gas reservoir was found with a long segment of distribution in the Sebei Gas Field, Qaidam Basin. Gas-channeling at the shallow strata is outstanding, especially the cementation quality of cement-formation interface is difficult to meet the requirement. To this end, the mud cake to agglomerated cake (MTA) method, having been successfully applied to the cementing of oil wells, was used for solving the gas-channeling of gas wells in this gas field. First, the effects of GM-II type mud cake modifier on the drilling fluid rheology and GA-III type agglomerated cake forming agent on the thickening time of cement slurry were evaluated and observed in experiments respectively. Second, a certain amount of GM-II was added into the drilling fluid slowly before targeting the pay zone, and this proportion should be maintained until the well completion was implemented. Third, the preflushing fluid (3 m3) is prepared based on the GA-III agglomerated cake, and its contact time with the mud cake at sidewall was maintained for 1.5 - 2 minutes. The application results from six wells in the Sebei Gas Field showed that the one-time success rate of cementing operations reached 100% and the one-time qualified rate of cementing quality was 100%. The high quality rate of cementing quality at casing-cement interface and cement-formation interface reached 95.16 - 100% and 80.01 - 98.11%, respectively. By using the MTA method, the cementation strength at cement-formation interface was greatly increased by 6.53 - 23.21 times. It provides a new technical means for solving the cementing quality problem of shallow gas wells.
- 出版日期2014
