RESERVOIR CHARACTERIZATION, DETERMINATION OF THE ENVIRONMENT

ABSTRACT

Utilizing sedimentological characteristics and the sand bodies' quality as reservoir indicators, the XY Well reservoir was characterized. Six lithofacies were recognized, namely laminated mudstone (ODI), Bioturbated sandstone (0D2), Wavy lenticular heterolith (0D3), Wavy bedded sandy heterolith (0D4), fine grained mm scale laminated sandstone (0D6), and lenticular muddy heterolith (0D7). Two hydrocarbon bearing reservoirs were also identified at depth 3160-3195ft (35ft) in Core I and at depth 3220-3226ft (6ft). The porosity values in Core 1 range from 12.6% - 41.1% with an average of 31% and permeability range of 21.9-1560md with an average 995md. Core 2 porosity values range from 20.5-38.1 with an average of range of 18.9-2200md with an average of 986md. The values show good to excellent porosity and very good permeabilities. The reservoir quality which is excellent is dependent on the facies, grain sizes and sorting which are fine to medium grained and a moderately depicting a moderately high energy environment. The bioturbation structures also enhance fluid flow, hence the high vertical permeability values. The various parameters above indicate deposition in a tidally influenced environment probably a distributary channel fill.