湘中涟源地区复杂地质结构与天然气勘探潜力

湘中涟源地区处于中扬子板块南部边缘,特殊大地构造位置与多期次构造运动叠合导致该区复杂地质结构和多样的构造样式。对于该区主要油气勘探目的层——晚古生代构造层而言,早期挤压应力导致以缩短变形构造样式为主,晚期应力松弛期,以滑脱回缓构造样式为主。凹陷总体属于盖层滑脱式逆冲褶皱组合。凹陷西部发育叠瓦逆掩冲断带、中部为隔挡式褶皱带、东部为滑覆断皱带。钻井揭示凹陷具丰富的生油气物质基础,纵向上有效储盖组合和构造组合指示中部隔挡式褶皱区最具天然气勘探潜力。逆断层下隐伏圈闭、凹陷内的低背斜和近凹陷中心的深盆气等的研究对该区油气潜力具有重要意义。

Analyses on the complex geologic structure and its gas exploration potential in Lianyuan region of middle Hunan province

Lianyuan region is located in the south margin of Middle Yangtze plate in Hunan province.Special tectonic position and multistage tectonic movement had led to complicated geological structures and diversified structural styles in this region.The target strata of oil and gas exploration in this region is late Paleozoic tectonic layers,which are dominated by shortened deformed structures in early period due to compressional stress,and sliding structures in late period during stress relaxation.The structural pattern in Lianyuan depression generally belongs to caprock detached thrust fold assemblage,with imbricated overthrust belt developed in the west part of the depression,barrier fold belt in the middle,and sliding nappe fault-fold belt in the east.It had been revealed by drilling that the depression holds abundant material base of oil and gas generation.The effective vertical reservoir-seal assemblage and structural assemblage indicate that the barrier fold belt in the middle has the most gas exploration potential.Concealed traps under reverse fault,low anticlines and deep basin gas near depression center are of important research significance to potential oil and gas.