Residual strata and hydrocarbon accumulation model of marine sediments in Subei Basin

Abstract

Based on the understandings of previous studies and exploration results, with the analyses of regional geophysical profiles and drilling data, it was discussed in this paper the deformation and distribution of marine sediments in the northern Jiangsu area under the superimposed transformation of Indosinian-Yanshanian compressional structures and Himalayan extensional structures. On this basis, the possible types of hydrocarbon accumulation and their key controlling factors of the study area were summarized by comprehensive analysis of accumulation assemblage. Results indicate that: (1) Bounded by Huaiyin-Dongtai fault, the Lower Paleozoic strata dominate the remaining strata of the west side, which basically show a stratum inversion in vertical direction and gradually change from old to new from north to south. The remaining strata of the east side are dominated by the Upper Paleozoic, which are normally distributed vertically and gradually change from old to new from north to south. (2) There are four types of hydrocarbon accumulation related to marine strata in the northern Jiangsu area, including early-stage primary-generation and residual type, late-stage new-generation and ancient-storage type, late-stage ancient-generation and new-storage type, and ancient-generation and ancient-storage type. For the early-stage primary-generation and residual type, two factors must be occurred: the favorable area for early accumulation and the weak degree of reconstruction and damage in the Yanshanian period. For the late-stage new-generation and ancient-storage type, the connection between continental hydrocarbon kitchen and marine reservoir is needed. For the late-stage ancient-generation and new-storage type, there must be late hydrocarbon generation kitchen and vertical migration channel to continental reservoir. For the late-stage ancient-generation and ancient-storage type, there must be late hydrocarbon generation kitchen and vertical regional cap rocks. The late-stage ancient-generation and new-storage type is a favorable target for recent breakthroughs in marine exploration, and the late-stage ancient-generation and ancient-storage type is favorable for further exploration.

Keywords

• hydrocarbon accumulation model
• hydrocarbon accumulation condition
• tectonic movement
• marine strata
• subei basin