A new insight on sedimentary facies of the Miocene to Pliocene Agbada Formation, offshore Niger Delta Basin, Nigeria

Abstract

The Niger Delta Basin contains rich oil and gas resources and has always been a focus for oil and gas exploration. Further research on the sequence stratigraphy and sedimentary facies is particularly significant in hydrocarbon exploration. In this study, the sequence stratigraphic structure and sedimentary facies of the Miocene and Pliocene Agbada Formation in the southeastern part of the Niger Delta were studied based on the integrated investigation of coring, well logging, seismic and geological data. The results show that: (1) One Type 1 and three Type 2 sequence boundaries are identified in the Agbada Formation. Based on the identified sequence boundaries, the Agbada Formation can be divided into three third order sequences SQ1, SQ2 and SQ3, which are well-developed, isochronal and traceable in this area.(2) The Agbada Formation in the study area was consisted of delta front, gravity flow channel and turbidite fan deposits.The latter two appeared at the bottom of SQ3 and SQ1, respectively. Moreover, the delta-gravity flow accumulation development model in the study area was established. (3) The main factors affecting the formation of gravity flow included sufficient sediment supply and specific triggering mechanism, which both induced the failure of delta front/slope and the consequent debris flows/turbidity currents. The discovery of gravity flow might be of great significance for further hydrocarbon exploration.