Development of Low-Permeability Carbonate Reservoir by Use of Horizontal Wells inMature South Umm Gudair Field in the Neutral Zone–A New Approach

摘要

The South Umm Gudair (SUG) oil field located in the Neutralzone between Kuwait and Saudi Arabia has produced since1968 from an active water drive carbonate reservoir of LowerCretaceous age. The lower zones are homogenous intervals ofhigher permeability which appear to be sufficiently swept bynatural water drive over a period of time. The upper zones ofthe reservoir are more heterogeneous and have lowerpermeability in the range of 50-150 millidarcies. These upperzones are relatively thin and are bound by tighter intervals thatact as effective barriers to the natural water drive system. Dueto the presence of barriers and low permeability intervals,these zones have been poorly swept resulting in significantvolumes of by-passed oil remaining in these parts of thereservoir.The new approach of exploiting these reserves by drillingand completing 4 horizontal and 2 horizontal side track (HST)wells targeting the lower permeability portions of the reservoirin the SUG field since January 2004; have yieldedconsiderable success in extracting significant incremental oilproduction with the added benefit of very low water cut. Thissuccess has led to field development plan to recover un-sweptoil reserves from these low permeability zones. This papersummarizes the various aspects of field development plantaking into consideration geology, reservoir data andproduction data while highlighting the successes of the newhorizontal and HST wells in the low permeability reservoirportions of the SUG field.