准噶尔盆地托斯台地区构造分析及油气勘探前景

STRUCTURE ANALYSIS AND PETROLEUM EXPLORATION PROSPECT OF TOSTAI AREA IN JUNGGAR BASIN

本文在研究了准噶尔盆地南缘西部托斯台地区地面地质及地球物理资料后认为:①托斯台为山前斜坡上的基岩隆起,主要是由北天山山前西部的北西向右旋走滑断裂在喜马拉雅期活动造成的,其前沿斜坡为隆断构造;②基岩隆起上的背斜构造分为三排:南排背斜有多期活动并伴有南倾中生代正断层,中排和北排背斜形成于喜马拉雅期,是北倾的背冲断裂造成的表皮构造;③托斯台的油气苗主要是喜马拉雅后期从山前的四棵树凹陷运移上来的;④前沿构造为最有利的勘探领域,其中肯斜型、断裂遮挡型及基岩型油气藏可能处于同一垂直空间上。

Based on the comprehensive study of the available outcrop and geophysical data of Tostai area,it is concludedthat: 1 )Tostai, a basement platform on the top of the front monocline of the Tianshan mountains, was formed by thenorthwestward dextral strike slip movement of the western North Tianshan Morntain in Himaiayan period; 2)Thereare three rows of anticlines on the basement platform :The southern row of anticiines were deformed by several struc-tural movements and accompanied by south-dipping Mesozoic normal faults; the middle and the northern rows wereformed during Himalayan movement and are thin-skinned structures resulted from north-dipping back thrust fault- ing; 3)The oil and gas seepage in Tostai was migrated from Sikeshu depression in the north in late Himalayan period;4 )The frontal structures are the most prospective exploration targets. The anticlinal, the fault-blocked and baserockreservoirs may be penetrated by one vertical well.