中—低丰度气藏盖层的空间分布及封闭特征

Space distribution and sealing characteristics of cap-rock of medium￣low abundance gas fields in China

陈默 2 王璐³ 冯金义⁴ 王少波⁴ 孔令江⁴ 赵永峰⁴

东北石油大学CNPC断裂控藏实验室，黑龙江 大庆 163318 中国石油大庆油田有限责任公司第一采油厂，黑龙江 大庆 163000 中国石油大庆油田有限责任公司第六采油厂，黑龙江 大庆 163000 中国石油大港油田公司勘探开发研究院，天津 300280

Laboratory of CNPC Fault Controlling Reservoir, Northeast Petroleum University, Daqing 163318, China No.1 Oil Production Plant, Daqing Oilfield Co. Ltd., PetroChina, Daqing 163000, China No.6 Oil Production Plant, Daqing Oilfield Co. Ltd., PetroChina, Daqing 163000, China Research Institute of Exploration and Development, Dagang Oilfield Company, PetroChina, Tianjin 300280, China

文中以四川盆地中部气田为重点解剖对象，在全面分析中—低丰度气田盖层发育特征基础上，系统分析了中—低丰度气田盖层发育特征、封闭能力及对天然气分布的控制作用。研究表明，我国中—低丰度气田盖层以泥质岩为主，单层厚度小，横向连续性差，分为分隔层、局部性盖层和区域性盖层3级。盖层排替压力较低，普遍小于5 MPa，但由于气田主要分布在凹陷区，地层倾角缓，较小的排替压力可以使天然气大面积成藏。盖层总体表现为3级封盖模式：分隔层直接封闭，局部性盖层封隔，区域性盖层总控。气藏在分布上表现为大面积连片。

Based on the overall statistics of cap-rock development characteristics in Chinese medium￣low abundance gas fields, taken the gas field in the central of Sichuan Basin as the key research object, cap-rock development characteristics, sealing ability and control action of the gas distribution in Chinese medium￣low abundance gas fields are analyzed systemically. Research shows that Chinese medium￣low abundance gas field cap-rocks are dominated by mudstone, small thickness of monolayer, poor lateral reservoir continuity, which are divided into three parts, separation layers, localized cap-rock and regional cap-rock. The displacement pressure of cap-rock is low, generally less than 5 MPa. Because gas fields are located mainly in depressed area with slow strata dip, smaller displacement pressure can cause wide gas reservoir-forming. In total, cap-rock shows three-part-sealing mode: direct separation layers sealing, localized cap-rock sealing, regional cap?-rock overhead control, the gas reservoir is generally distributed in large area.

10.6056/dkyqt201601007