燕南断裂带封堵性分析

Sealing property of Yannan fracture belt.

辽河坳陷东部凹陷葵花岛断裂背斜构造带由燕南断裂带控制发育，是渤海海域的重要油气勘探区。燕南断裂带是郯庐断裂的组成部分，其断裂绝大多数是正断层。钻于该断裂带西侧的７口井证实，已见油气的４口井油气层均靠断面封闭。利用测井资料分析断裂结构面力学性质，认为断面很致密，发育断层泥（ＫＨ４井２４０２ｍ深度断面能够封闭的最大油柱高度为６７．４８ｍ）；根据横切断裂的地震剖面（道积分剖面），认为广泛发育断层泥；根据流体性质、压力系统和断面图分析，各断块互不连通，断裂两盘砂岩有相接处，靠断层泥封闭。燕南断裂带主要活动时期为早第三纪沙河街组和东营组沉积期，该阶段断裂间歇性活动，断面开启与封闭交替；馆陶组沉积期以来，断裂活动微弱，根据葵花岛构造带异常地层压力形成时期和油气显示层位，认为断裂带在东营组沉积期末形成封闭。图５参１０（王孝陵摘）

Kuihuadao faulted anticlinal belt in the east depression of Liaohe basin, one of the most important petroleum exploration blocks in Bohai Gulf region, is controlled by the development of Yannan fracture belt. Yannan fracture belt, a cluster of normal faults located on the west of Kuihuadao structure, is a part of the famous Tanlu faulted belt in China.Four wells with commercial oil and gas flows among 7 drilled in Kuihuadao structure proved that the oil and gas reservoirs are sealed by fault planes. Logging data and fracture mechanics analyses suggest that the fault planes are rather “tight”. Seismic profiles crossed the fault plane show that the fault gouge is well developed in the area. Fluid property, pressure system and fault plane map analyses indicated that the faulted blocks in the area are isolated by the faults, at the sand juxtaposition along faults, however, the fluids are sealed by fault gouge. The major activity period of Yannan fracture belt is the deposition stage of the Shahejie and Dongying Formations, during which the Yannan faults opened and closed intermittently. The activity of Yannan faults weakened from the Guantao stage. According to the intervals of oil and gas shows, and the periods of abnormally pressure occurred and developed in Kuihuadao structure, the authors believe that the Yannan fracture belt was closed from the end of Dongying stage.