Application of Geostatistical Inversion for Developing Thin Carbonate Reservoirs in Umm Gudair Field, West Kuwait

Deeper carbonate pays in the Umm Gudair oil field of West Kuwait are the focus of the study in this paper. Oil is produced mainly from a pair of vertically stacked thin reservoir units separated by a thin impermeable layer. Subsequent to their discovery in 1984 most of the development wells have been drilled vertically over the structural highs to exploit them. Deterministic inversion and porosity modeling could not resolve the individual reservoir units. But the results show the presence of highly porous reservoir geobodies on the flanks of the West Umm Gudair structure. Horizontal wells or re-entry by side tracking from existing vertical wells are planned to exploit these reservoir bodies. Successful planning and drilling of horizontal wells requires (1) precise spatial distribution of individual reservoir units and (2) the uncertainty associated with reservoir predictions. Present geostatistical approach not only helps in resolving these thin reservoir units but also in mapping their spatial distribution in detail. Multiple realizations achieved in the geostatistical inversion process are the key input in preparing 3D geological models and for future development plans for these thin reservoir units.