Mud shale diapir structure and hydrocarbon distribution in the Rio del Rey Basin of Cameroon

The Rio del Rey Basin is located in Cameroon and the northeast of the Niger Delta. It is rich in oil and gas resources, and has more than 30 years of oil and gas exploration and development history. Long-term regression and delta sedimentation since the Eocene have formed the present Rio del Rey passive continental margin basin. Three stratigraphic units developed, including the Akata, Agbada and Benin formations respectively from bottom to top. In the process of delta progradation, the extensional, shale diapir and toe thrust tectonic zones were formed from north to south and also from onshore to offshore because of the gravity action of continental margin and the plastic over-thrusting of deltaic mudstone. In the mudstone diapir tectonic zone, many diapir anticlines or faulted-anticlines and lithologic traps related to mudstone diapirs or mudstone ridges have been formed. The large oil and gas fields that have been discovered to date are mainly related to these traps. At the same time, the activity of mudstone diapirs also provided superior conditions of reservoir and migration, which promoted the oil and gas enrichment and high yield in the diapir tectonic zone. Therefore, the mudstone diapir tectonic zone and the traps associated with mudstone diapirs are still the main targets for further exploration potential in the Rio del Rey Basin.