INTEGRATED APPROACH FOR RESERVOIR CHARACTERIZATION, STATIC MODELLING, AND VOLUMETRIC ESTIMATION OF TWO RESERVOIRS

ABSTRACT

Integration of 3D seismic, wireline logs and checkshot data has been used to characterize the “Prime field”, build a robust static model, and estimate in-place hydrocarbon volumes for two reservoirs in ‘Prime Field’, Onshore Niger Delta. A suite of Schlumberger software including Petrel and Techlog as well as workflows were utilized to define the facies geometry, structural styles, hydrocarbon type and distribution, reservoir property heterogeneity and estimates of hydrocarbon volume within the modelled 3D static reservoirs. Two reservoirs of interest were identified and correlated across all 4 wells with average thicknesses of 280ft and 292ft for reservoirs 1 and 2 respectively. 3 facies types- sand, shaly-sand and shale have been interpreted from facies analysis. Sand units were inferred to be of channel and shoreface origin and the shales marine using the standard log signatures from the GR logs. Structural analyses reveal the occurrence of Collapse Crest Structures, Simple/Faulted Rollovers, and Regional Foot Walls/Hanging Walls dominating within the mainly extensional zone and these constitute the major hydrocarbon traps in the area. Well to seismic ties were established for all two reservoirs to carry over interpretation from the wells to the seismic volume. Top structure maps in time and depth were generated for the three reservoirs of interest. 3D grid models were built and populated with properties using the Stochastic Indicator Simulation and Gaussian Random Function algorithms. The average reservoir porosity and water saturation values for reservoirs are 0.2598 and 0.408 for Beta reservoir, and 0.2533 and 0.423 for Gamma reservoir respectively. Oil initially in-place for Beta and Gamma reservoirs are 545MMSTB and 637MMSTB and Gas initially inplace was 22186MMSCF and 20081MMSCF based on estimates from the static models built.