石膏含量对盐膏层蠕变速率影响的研究

STUDY OF EFFECTS OF GYPSUM CONTENT ON SALT-GYPSUM STRATUM CREEP RATE

针对深部盐膏岩地层岩芯获取难度大的难题,依据现场岩屑的矿物组分,人工压制盐膏岩试验试样,蠕变试验表明,相同组分的天然岩芯和人造岩芯具有相似的蠕变规律。据此,通过对人造岩芯进行不同围压和相同温度下的蠕变试验,得到各种矿物组分含量对其蠕变的影响。结果表明:在相同应力和温度条件下,盐含量多的复合盐岩的稳态蠕变速率较高,膏含量多的复合盐岩的稳态蠕变速率较低。同时,对滨里海盆地的天然岩芯进行理化性能分析,同样验证了以上的结论。试验结果在塔里木克深区块的超深井得到验证,并指导钻井液密度的合理确定。

Because of the coring difficulty in deep-layer salt formation,artificial cores were made according to its field mineral composition. Creep tests were conducted which shows that the natural core and the artificial core with the same mineral composition had the same creep law. In light of this finding,further creep tests of the artificial core were carried under different confining pressures and same temperature,and the effects of contents of different mineral compositions on the creep were obtained. The test results showed that under the same stress and temperature condition,the steady-state creep rate of high-salt salt-gypsum formation was higher,while the high-gypsum salt-gypsum formation was lower. At the same time,the physico-chemical property analysis were conducted for natural core in Caspian Basin,which also verified the above conclusion. The test result was tested in two ultra-deep wells in Keshen block in Tarim oil field and was applied to determination of drill fluid density.