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1985年以来,地矿部华北石油地质局在塔里木盆地北部钻深探井14口,几乎每口井都不同程度地发现膏盐层,其中有3口井(沙10、沙24、沙42井)钻遇大段膏盐层段。本文分析了钻膏盐层的井身结构特点和套管设计依据,提出套管最大临界外挤载荷可按该井段的上覆岩层压力计算,认为下入高强度的无接箍套管是防止膏盐层蠕动挤毁套管的有效方法;两层尾管重迭封固膏盐层,可显著地提高套管的抗外挤能力;使用双心钻头可防止膏盐层卡钻;用水力扩孔器扩眼可使下部井眼有足够的尺寸,以保证超强度套管的下入;选用高密度的饱和盐水钻井液和控制CI~-含量可有效抵抗盐岩层的塑性流动,保证安全钻井;利用测井资料对地层的蠕变速度进行了计算尝试,通过实践总结出一套科学的钻膏盐层防卡操作技术措施。此外,还探讨了石膏岩层尾管固井工艺。
Since 1985, the North China Bureau of Geology and Mineral Resources of the Ministry of Geology and Mineral Resources has drilled 14 exploration wells in the northern part of the Tarim Basin. Gypsum salts have been found to varying degrees in almost every well of which 3 wells (Sha 10, Sha 24 and Sha 42) Encountered a large section of salt gypsum section. In this paper, the wellbore structure characteristics of drill salt and its design basis are analyzed. The maximum critical external crushing load of casing is calculated according to the overburden pressure of this well. It is considered that the high strength non-ferrule casing is Prevent the gypsum salt layer creep crushing collapse casing effective method; two layers of tail pipe overlap sealing paste salt, can significantly improve the anti-extrusion ability of the casing; the use of double heart drill bit to prevent the paste salt layer stuck; water Reaming reaming hole can make the lower part of the hole has enough size to ensure super-strength casing into the selection of high-density saturated brine drilling fluid and control CI ~ - content can effectively resist the plastic flow of salt rock layer to ensure Safe drilling; using the logging data to calculate the creep speed of the formation, attempting to sum up a set of scientific anti-jamming operation technical measures of drilling salt by practice. In addition, the cementing process of gypsum strata tail pipe is also discussed.