Depositional Setting and Petrophysical Evaluation of Reservoir of the K-Field in the Western Offshore Depobelt, Rio Del Rey Basin, Cameroon

Abstract

The Rio Del Rey basin is a prolific petroleum field on the Continental margin of the gulf of Guinea and is one of the major producers in the gulf. The study was carried out using Schlumberger Petrel and Synergy Interactive Petrophysics software for the sequence stratigraphy and petrophysical analysis to study the depositional setting of the Rio Del Rey Basin, using Well Log Data. Five sequence boundaries, five Transgressive Surfaces and four Maximum Flooding Surfaces were identified from wireline log. The progradation of sediments is characterised by a number of stacked sequences deposited in a coastal complex, with offshore, shoreface, beach and tidal deposits. Sequence one contains mostly Lower shoreface deposits of fine to very fine laminated sediments. In sequence two there is, an increase proportion of upper shoreface deposits. Sequence three is dominated by upper shoreface and distributary channels deposits with a concomitant reduction of lower shoreface deposits while sequence four and five contain mostly stack distributary channels and beach deposits. The study has aided the identification and interpretation of two gas bearing and two oil bearing zones in the three wells based on hydrocarbon-typing using the sonic-resistivity logcombination. The total and effective porosities of the reservoirs range from 20% to 31% and 15% to 31% respectively, indicating that the reservoirs have very good porosities. The ratio of the net to gross thickness of the reservoirs is as high as 0.83. The water saturation values of the reservoirs ranges from 11% - 80%. The results of the petrophysical investigation show that the sand formations have good reservoir properties. The vertical facies succession records a migration/translation of laterally linked depositional environment, controlling reservoir properties like geometry, heterogeneity, porosity and permeability.