贺西地区中生代沉积坳陷划分及油气远景概述

DIVISION OF MESOZOIC SEDIMENTARY DEPRESSIONS AND OIL POTENTAL IN WEST OF HELAN MOUNTAINS

林梁

Lin Liang

该区面积50余万平方公里,可分为阿拉善坳陷区和北山隆起区,前者包括11个坳陷,中、新生界厚2000—8000m 不等。多数坳陷的中下侏罗统、下白垩统发育;大部凹陷具备生油条件,但凹陷规模较小。额济纳旗-阿拉善右旗一线以西的中下侏罗统、走廊坳陷北段及宗南、宗北诸坳陷的下白垩统含油气远景较好。

The Mesozoic sedimentary-structural units within the area of 500000 km to the westof the Helan Mountains,south of the boundary line,east of Xinjiang and north of the Qi-lian Mountains are dividid into Alxa depressed region (including 11 depressions) andBeishan uplift region according to recent data of geology and geophysical exploration.Thebasements are composed of metamorphic rocks belonging to Pre-Caledonian,Caledonianand Hercynian Epoches and the overlying beds are composed of Meso-Cenozoic sedimentswhich range from 2000 to 8000m in thickness.The structural evolution shows distinctdifferentiation in east and west parts.Middle-Lower Jurassic and Lower Cretaceous sediments are better developed in thewestern depressions which have the conditions for hydrocarbon generation,but the areasare usually not broad enough (in more than 80 depressions,only 40% have the areasgreater than 1000km).The Middle-Lower Jurassic to the west of Ejin Qi-Alxa Youqi,and the Lower Cretaceous in the northwest part of the corridor,Zongnan and Zongbei De-pressions have better oil potential.

10.11743/ogg19900411