青海木里冻土区天然气水合物钻探施工技术

摘要

钻探取心是天然气水合物资源调查研究的一种重要技术手段，也是识别天然气水合物最有效的方法之一。青海木里煤田三露天调查区地质构造复杂，水合物钻探施工时极易出现孔壁坍塌、水合物分解、气侵泥浆及孔内涌气、涌水、漏失等问题，取芯困难、钻进效率低。针对这些技术难题，开展了泥浆制冷技术、大口径绳索快速取心钻进技术、聚合物低温泥浆工艺及泥浆防塌体系、钻孔结构及钻进参数优化、钻头选型、气体防喷等技术工艺研究，并在现场实践中取得了较好的效果，为今后青藏高原冻土地带进行天然气水合物钻探施工提供借鉴。%Borehole coring is one of major technical means to explore and study natural gas hydrate, also one of effective methods to identify natural gas hydrate. The Third Surface Coalmine exploration area in Muri coalfield, Qinghai has complicated geological struc⁃tures, during the drilling operation is easy to happen borehole wall collapse, hydrate decomposition, mud gas invasion, inrush of gas and water, circulation loss, difficult coring and low drilling efficiency etc. In allusion to above hard nuts have carried out measures of mud refrigeration, large diameter wire-line fast coring drilling and polymer low temperature mud technologies, as well as technical studies on mud collapse prevention system, borehole configuration, drilling parameters optimization, bit type selection and gas blowout preven⁃tion. Thus archived good effects in site operation practices and provided reference for natural gas hydrate drilling operation in Qinghai-Tibet Plateau permafrost region henceforth.