Challenges to Explore Shallow Sandstone Reservoir for Optimized Unconventional Development Strategy in Kuwait

Ferdous, Hasan; Chaudhary, Pradeep; Ahmad, Fatma; Abbas, Faisal; Ahmed, Khalid; Llerena, Javier; Sammak, Ibrahim

Challenges to explore a shallow poorly-consolidated viscous oil bearing sandstone reservoir is presently being undertaken in Kuwait through extensive core sedimentology and integrated reservoir evaluation efforts to optimize the future development and production strategy of the reservoir.

The reservoir grossly consists of two separate sand packages, predominantly of deltaic origin influenced by estuarine-transitional-marine settings. Sand-bodies commonly represent multi-stacked fluvial to distributary channel-fills and associated facies resulting to stratified reservoir intervals with variable degree of fluid saturations. High-resolution sequence correlations reveal the dominant lowstand and transgressive depositional regimes for reservoir development, which demands finer scale reservoir characterization for precisely alike interval relationships.

Reservoir characterization uncovers high matrix contents along with various cement phases, predominantly calcite, dolomite, and clay minerals control the pore-networks with inter-granular primary porosity and generation of secondary pores, essentially portray the pore-geometry, thus impacting the overall petrofacies and fluid flow-path.

Structurally, the reservoirs dip very gently towards north-east with no definite structural closure. Viscous oil accumulation is mainly controlled by lithofacies variations and extent of biodegradation which resulted in stratigraphic trapping. Lithofacies distributions and diagenetic modifications have overall characterized the petrofacies with variable fluid saturations into a stratified-reservoir condition. Irregular and dubious presence of free and dissolved gas furthermore enhances the overall complexity and challenges to the development strategy.

Thus seemingly simple channel-based reservoir intervals have been greatly altered by post-depositional diagenetic episodes that need to be understood and evaluated. This necessitates an arduous regular and unconventional drilling, completion and production strategy to pursuit the precise pay-intervals for the reservoir's development.

Keeping the challenges in mind, all pertinent data related to integrated geology, drilling, and production are closely evaluated to understand the reservoir trends and embrace the needed approach, ensuring the optimal completion and production strategy to meet the long-term development plan for this viscous oil bearing asset.

AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013