贵州裸露岩溶地下河系统污染通道识别钻探技术

Drilling techniques for pollution pathway identification in exposed karst subterranean river systems in Guizhou

摘要:

贵州裸露岩溶区地下河系统发育、岩溶发育强烈、水文地质条件复杂，地下河系统易受地面污染源渗滤液浸入引发严重污染问题。地下河系统污染通道隐蔽性强、空间狭窄、各向发育不均匀，精准识别难度大。为揭露识别污染通道，钻探成孔施工面临软硬互层与软弱不均、强岩溶地层易孔斜、大溶洞钻孔轴线易偏移和套管拆断、自然水力坡度小的地下河系统示踪剂迁移缓慢等难题，污染通道揭露识别难度大、效率低。采用防斜保直、大岩溶套管穿越封隔、孔内激化促示踪剂迁移等技术措施，保证了勘查孔垂直度，并为测井、示踪试验及水样采集等工作提供精准的钻孔通道，实现了污染通道的精准揭露和快速识别。对同类地层精准揭露和高效识别污染通道的钻探施工有参考和借鉴意义。

Abstract:

The exposed karst region in Guizhou features a complex network of underground river systems characterized by extensive karst development and intricate hydrogeological conditions. These systems are highly susceptible to severe contamination from surface pollutant sources due to percolation of leachates. The pollution pathways within these underground river systems are challenging to precisely identify owing to their concealed nature， narrow spatial extent， and anisotropy. To expose and identify contaminated channels， drilling operations face several difficulties， including alternating soft and hard layers， non-uniform weak zones， significant karstic formations causing borehole deviation， large cavities leading to casing misalignment or breakage， and slow tracer migration due to low natural hydraulic gradients in the underground river systems. Consequently， the identification and exposure of pollution pathways are both difficult and inefficient. To address these challenges， several technical measures were employed， including anti-deviation and vertical maintenance techniques， large karst casing passage and sealing， and in-hole activation to promote tracer migration. These measures ensured the verticality of exploration boreholes， facilitating accurate logging， tracer testing， and water sampling. This approach enabled the precise exposure and rapid identification of pollution pathways. The methodologies and technical measures adopted in this study offer significant reference and practical insights for the precise exposure and efficient identification of pollution pathways in similar geological formations.