羌塘盆地天然气水合物钻探试验井取样技术与施工实践

Sampling Technique in Gas Hydrate Drilling Test Well in Qiangtang Basin and the Construction Practice

摘要:

羌塘盆地天然气水合物钻探试验井工程位于羌塘盆地西北部，海拔4998～5100 m。羌塘盆地是青藏高原年平均地温最低、冻土层相对较厚的地区，所处的水文地质及工程地质环境极其复杂，多年冻土层经反复冻胀融沉，地层破碎。另外，该处地层节理、裂隙、小断层和地下水极其发育，施工条件十分恶劣和困难。从取心钻具结构改进、钻头设计、冲洗液配方以及钻孔结构等方面总结了近年在羌塘盆地实施天然气水合物钻探试验井工程的实践和经验，为未来高海拔地区天然气水合物及其他矿产资源勘探提供参考。

Abstract:

The test well engineering of gas hydrate drilling is located in northwest of Qiangtang basin with altitude about 4998～5100 meters, where the hydrogeological and engineering geological environment is extremely complex with the lowest annual mean ground temperature and thick permafrost in Qinghai Tibet Plateau. The construction is very difficult with cleavage, fracture, small fault and groundwater extremely developed. In this paper, the practice and experience of test well engineering of gas hydrate drilling in Qiangtang basin are summarized on the improvement of coring tool structure, bit design, flushing fluid formulation and borehole structure, which could be reference to the exploration of gas hydrate and other mineral resources in high altitude regions in future.