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.