大地电磁测深在桂中坳陷油气勘探中的应用

通过桂中坳陷两条大地电磁测深剖面研究桂中坳陷及周边的地质结构。对构造单元及断层组合特征及古生物礁显示的分析结果显示:坳陷可划分为北部斜坡、西部斜坡、中部凹陷、东部斜坡四个次级构造单元;坳陷是下古生界浅变质岩基底上发育起来,泥盆系平均达4 000 m;泥盆系中下统是古生物礁发育的主要层位,电性特征总体表现为相对稳定的低阻,二维反演断面中发现低中显高的电性异常体,推测为古生物礁;中部凹陷背斜十分发育,中部凹陷及其边缘是油气勘探远景区。

THE APPLICATION OF MAGNETOTELLURIC SOUNDING TO OIL AND GAS EXPLORATION IN CENTRAL GUANGXI DEPRESSION

According to the exploration results of two magnetotelluric sounding profiles in central Guangxi area,the authors have studied the geological structure of central Guangxi depression and its surrounding areas.Central Guangxi depression is divided into four sub-units,i.e.,northern slope,western slope,central depression and eastern slope.The depression was developed on the basis of lower Paleozoic epimetamorphic rock series,and the average thickness of Devonian strata reached 4 000 m.The electrical characteristics show that the Middle-Lower Devonian strata constitute the main horizon of the biogenic reef,and the electricity is characterized by relatively stable low resistance.Two-dimensional inversion of the section has revealed an electrical anomalous body with the character of "high in low",which is inferred to be a reef.Brachyanticlines are well developed in the central depression,and hence the central depression and its surrounding areas are considered to be favorable areas for oil and gas exploration.