青海木里三露天冻土区天然气水合物形成与分布地质控制因素

到目前为止，我国陆域冻土区天然气水合物仅限于青海木里三露天地区，钻井揭示该区天然气水合物分布较为分散，那么是什么地质控制因素影响到该 区天然气水合物分布的不均匀性？基于此问题，此次在过去工作基础上，重点对神华投资项目实施的青海木里三露天天然气水合物系列钻井揭示的地质资料及各种样品分析测试结果进行综合 分析，探讨该区天然气水合物气源成因类型、气源有效供应量、不同产状和性质断裂对天然气水合物形成与分布的控制作用。研究结果显示，研究区三露天发现天然气水合物的中西部地区气 源以热解成因气为主，没有发现天然气水合物的东部地区气源则以微生物成因气为主，显示研究区气源成因类型对天然气水合物形成与分布具有重要控制作用。研究区西部地区气源有效供应 量最好，中部地区次之，东部地区最差，这种气源有效供应状况直接影响着研究区中西部地区与东部地区天然气水合物形成与分布的差异性。F₁、F₂逆冲断层控制着研究区中西部天然气水合物的形成与分布；F₁逆冲断层在研究区东中部地区产状和性质发生改变，不利于天然气水合物的形成与分布；F₃₀正断层性质影响到研究区西部地区局部天然气水合物的形成与分布。

Geological Constraints on Gas Hydrate Formation and Distribution in Sanlutian Permafrost of Muli,Qinghai

Up to date, onshore permafrost-associated gas hydrate is just restricted to the area of Sanlutian of Muli in Qinghai in China; drilling holes revealed that gas hydrate distribution was very scattered in this area; then what geological constraints affect such heterogeneity of gas hydrate distribution in this area? Targeting this question, based on past work, the geological data and analytical results of various samples collected from the series of gas hydrate drilling holes invested by Shenhua Corporation are emphatically and comprehensively studied in Sanlutian of Muli in Qinghai, to discuss constraints of the genetic type of gas source, the available supply amount of gas source, the different occurrence and nature of faults on gas hydrate formation and distribution. Study results show that the genetic type of gas source is mainly thermal in the middle to west of the study area of Sanlutian where gas hydrate is found and it is mainly microbial in the east of the study area where gas hydrate is not found, indicating that the genetic type of gas source plays an important role in controlling gas hydrate formation and distribution in the study area. The available supply amount of gas source is the best in the west of the study area, and it is the second in the middle, and it is the worst in the east; this available supply circumstance of gas source directly affects the difference of gas hydrate formation and distribution between the middle to west and the east of the study area. Thrust faults F₁ and F₂ control gas hydrate formation and distribution in the middle to west of the study area. The occurrence and nature of the thrust fault F₁ is various in the east to middle of the study area, which go against gas hydrate formation and distribution. The nature of normal fault F₃₀ locally affects gas hydrate formation and distribution in the west of study area.