莺歌海盆地泥-流体底辟树型输导系统及运移模式

莺歌海盆地发育多期泥-流体底辟。底辟活动的多期性造成底辟区断裂和裂隙不断开启,输导天然气从深部向浅部垂向运移,充注底辟两侧及周缘的砂体,在剖面上构成树形样式,称之为底辟树型输导系统。底辟树型输导系统连通了浅层和中-深层的构造和岩性圈闭,是莺歌海盆地中央凹陷带构造及岩性天然气藏成藏的主要输导通道和样式,其相应运移方式分为能量保持型和能量释放型两种。本文提出了莺歌海盆地中央凹陷带发育底辟树型输导系统及其运移的地质模型,泥-流体底辟活动控制下的底辟树型输导系统及其运移模型是对伸展-转换盆地油气成藏理论的发展和补充。

Tree-shaped conducting systems and related tree-shaped migration model of mud-fluid diapir in the Yinggehai Basin

The Yinggehai Basin is a Cenozoic sedimentary basin with high geotemperature and overpressure.There are many diapirs in the Central Depression of the basin.Limited by exploration and knowledge level,many problems and argues existed on distribution of overpressure,migration and accumulation of the natural gas.The conducting system and migration model of tree-shaped mud-fluid diapir were presented in this paper,namely,the faults,fissures and the sands around and the top of diapirs,developed in the varied active periods on diapirs,might be important elements which made up the conducting system of the Central Depression of the basin.The faults and fissures,conducting hydrocarbons from the deeper source rocks,acted as the vertical migration pathways,while the sandstones around the top of diapirs worked as the lateral conducting pathways.The diapir-causing faults,fissures and sandstones that distributed around the top of the diapirs constituted the tree-shaped conducting systems,and the corresponding migration model of natural gas was named as tree-shaped migration model around the diapirs.The tree-shaped conducting system and the related migration model was main conducting pathway and the accumulate model of the structural and lithologic gas reservoirs which was controlled by the mud-fluid diapir developed in the Central Depression of the Yinggehai Basin.The model could be classified into two kinds based on the migration modes:the energy-keeping and the energy-releasing models.This particular kind of conducting system and migration model generated the vertically superimposed gas formation,which allocated in both shallow and mid burial depth around the diapirs.The proposition of the conceptions of the tree-shaped conducting systems and the related tree-shaped migration model should be of great theoretical and practical significance in natural gas exploration in mid-deep burial depth of the basin.