Increase Productive Life and Add to In-Place Oil in Mature Reservoirs with Integrated Studies: Zubair Reservoir in Kuwait
The Zubair reservoir is an Albian siliciclastic reservoir on production for the last six decades. Cumulative production indicates a higher oil recovery factor than expected. An integrated study involving sequence stratigraphy, sedimentology, biostratigraphy, petrophysics and modeling techniques resulted in a better understanding of rock fabric, mineralogical composition, depositional settings and their evolution leading to discovery of more in-place oil and a rejuvenated development plan.
Petrographically, the formation comprises highly mature clastic deposits with variable and heterogeneously distributed argillaceous matter. The fine- to medium-grained sandstones are weakly overprinted by authigenic mineral precipitates. Whole rock and clay-fraction XRD indicate very low expandable clay minerals.
The deposits were rationalized into three levels of comprehensive descriptive and interpretative schemes. The expected geometries, dimensions, internal heterogeneities and reservoir qualities of the various facies associations were upscaled into Gross Depositional Environments (GDE) to increase the confidence and consistency of sedimentological interpretations from openhole logs alone. The palynologically constrained GDE indicate increased importance of deltaic as opposed to previously envisaged shallow marine processes.
Four low-order sequence stratigraphic sequences were identified: A basal transgressive set, a heterogeneous highstand deltaic and more homogeneous channel-dominated lowstand set, which in turn are capped by transgressive deltaic to open marine deposits.
Azim, S. A, Al-Anezi, S, Kostic, B, Bryant, W, Hoppe, M, Al-Blayees, M, Al-Qattan, S and Al-Saad, B. (2013) Increase Productive Life and Add to In-Place Oil in Mature Reservoirs with Integrated Studies: Zubair Reservoir in Kuwait. Paper presented at the AAPG Annual Convention and Exhibition, Pittsburgh, May 19-22nd, 2013.
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