南海西部莺—琼盆地天然气勘探领域分析

AN ANALYSIS OF THE NATURAL GAS EXPLORATION AREAS IN YING QIONG BASIN IN WESTERN SOUTH CHINA SEA

从研究气源区和成藏模式入手，对莺歌海—琼东南盆地天然气有利勘探领域进行了分析和划分。莺—琼盆地依构造结构可划分出“箕型”、“复合型”和“碟型”三类凹陷（坳陷），后两者具高温高压特征，是富生气凹陷（坳陷）。以天然气主运移方向和气藏压力为依据，共分出纵向、横向和纵向—横向３大类共６亚类成藏模式。根据气源区和成藏模式所得认识，指出天然气有利勘探领域分布在６个地区：莺歌海盆地泥底辟构造带；琼西披覆背斜带；莺东斜坡构造带；莺歌海盆地临高构造带；琼东南盆地松涛３６—１构造带；琼东南盆地松涛２９—１构造带。进而细分出１０个气聚集带，其中有４个高压气藏聚集带和６个常压气藏聚集带。

Based on the study of the gas source areas and gas reservoir formation patterns,the areas favourable for gas exploration in Ying Qiong Basin are analyzed and divided.According to structural characteristics,three types of sags (depressions) as “half graben”,“combination” and “dish”may be divided in Ying Qiong Basin and the last two have the properties of high temperature and high pressure,being the rich gas generation sags (depressions).In accordance with the main gas migration direction and reservoir pressure,three major types (vertical,lateral and vertical lateral) and six subtypes of gas reservoir formation patterns are classified.On the basis of the understanding of the gas source areas and gas reservoir formation patterns,it is pointed out that there are six favourable areas there,i.e.the mud diapir structure belt in Yinggehai Basin,the drape anticline belt at West Qiong,the structural belt on East Ying slope,the Lingao structural belt in Yinggehai Basin and the Songtao 36-1 and 29-1 structural belts in Qiongdongnan Basin,then ten gas accumulation belts can be subdivided,in which there are four high pressure and six normal pressure ones.