Structural Evolution and Hydrocarbon Accumulation Conditions of the StrikeSlip Pull-Out Basin in the Central African Rift System: A Case Study of the Doseo Basin in Chad

Doseo Basin is the key block of CNPC's overseas oil and gas exploration currently in Chad, and important oil and gas discoveries have been made in recent years. Based on the latest drilling and seismic data, utilize geochemical analysis data, this paper systematically analyzes the tectonic evolution and basic petroleum geological conditions and hydrocarbon accumulation in the CNPC’s blocks of Doseo Basin, and identifies the next favorable exploration areas. Three mainly stages of tectonic evolution and three sets of favorable source rocks are mainly developed in Doseo Basin. The Kedeni Formation source rocks have large thickness, wide distribution, good organic matter type and high maturity, are the most favorable reservoir formation conditions. The fault system formed by multi-stage tectonic activities provides convenient channels for oil and gas migration and accumulation. The reservoir formation assemblages are dominated by lower generated and upper stored assemblages of Kedeni Formation. Many types of structural traps are developed, such as anticline, fault anticline, fault nose and fault block. The central depression is the main source of hydrocarbons generation, and hydrocarbons migrated closed vertically and laterally along faults formed structural reservoirs near the central depression. On the basis of this analysis, the next favorable exploration fields in the study area are defined. The structure-lithologic reservoirs in the north steep slope zone and the south slope zone, and the oil and gas exploration in the deep Mangara Formation are mainly the next favorable exploration areas. The research results point out the direction for the follow-up exploration in the study area, and it is hoped to open a new situation of exploration and consolidate the resource base for increasing oil and gas storage and production in Doseo Basin.