下扬子区上古生界构造作用与油气保存条件分析

基于中、新生代构造形变对下扬子地区海相地层及上覆盖层的影响,应用整体构造框架下的宏观保存体系评价思路,通过研究构造演化与隆升剥蚀、断裂构造作用、岩浆活动、水文地质条件、盖层的有效性等,对该区上古生界油气宏观保存条件进行了评价。(1)下扬子区上古生界油气保存条件地区差异性明显,具有"南北分带,东西分块"的特点;(2)下扬子区油气保存条件分为3类:句容—黄桥地区、海安凹陷中北部为Ⅰ类(有利)保存区;苏北盆地(东台—大丰地区、射阳地区、宝应—金湖南地区、姜堰—海安地区)、苏皖南地区(无为地区、望江—潜山地区、句容—常州地区)为Ⅱ类(较有利)保存区;下扬子其他地区为Ⅲ类(差)保存区。

Tectonic effects and hydrocarbon preservation conditions in Upper Paleozoic,lower Yangtze region

The tectonic deformations during the Mesozoic and Cenozoic influenced the marine strata and the overlying formations in the lower Yangtze region. The tectonic evolution history, uplift and denudation, fault activity, magmatic activity, hydrogeological condition and cap rock effectiveness of the study area were studied to evaluate the basin scale preservation conditions for oil and gas in the Upper Paleozoic. (1) The preservation conditions for oil and gas in the Upper Paleozoic vary in the lower Yangtze region, generally featured by "belts from north to south, and blocks from east to west". (2) The hydrocarbon preservation conditions were categorized to three types. Jurong-Huangqiao and the central and northern Haian Sag are most favorable for hydrocarbon preservation, judged as class Ⅰ. The North Jiangsu Basin (including Dongtai-Dafeng, Sheyang, Baoying-southern Jinhu, Jiangyan-Haian) and the southern Jiangsu and Anhui region (including Wuwei, Wangjiang-Qianshan, Jurong-Changzhou) are also favorable for hydrocarbon preservation, judged as class Ⅱ. The other areas in the lower Yangtze region have poor preservation conditions, and are judged as class Ⅲ.