Abstract
The South Umm Gudair (SUG) field is located in the northwest corner of the Divided Zone (DZ) bordering Kuwait and Saudi Arabia. It represents the southern plunge of Umm Gudair field in Kuwait in the north. The field is producing from the Lower Cretaceous Ratawi Oolite reservoir that is capped by shale limestone sequences of the Ratawi Limestone. The field was discovered in 1966.
There has been significant increase in the water cut throughout the field. The production data in the recent past has shown an increase in water production in a number of wells (50% to 80% water cut) and a resulting drop in oil production.
The field was subjected to three different development phases. In each phase, the Oil Water Contact (OWC) was getting shallower with time. Production logs were run in several wells that indicated water encroachment in individual wells. The reservoir pressure has dropped considerably and all producing wells are completed with electrical submersible pumps.
Efforts made to control the high water cut by conventional mechanical plug back techniques of shutting off the lower perforations were successful in the past but it did not sustain for a longer period of time. The water cone would soon get bigger and encroach the higher perforations with increased water cut, thus the wells would be producing below their optimum potential. It was observed that some advanced technology which could delay the water encroachment more effectively was needed.
This paper describes the case histories of successful applications of a deep penetrating polymer system that was used to create an impermeable gel barrier in the reservoir around the well bore that could sustain long-term water shutoff results in these SUG wells. In addition, the understanding of the reservoir, geology, fluid flow mechanism, and systematic approach of treatment design with proper placement techniques, provided insight into these treatments' success and of limiting the uncertainties involved.
The system was applied to several SUG wells and in all these cases excellent water shutoff results were obtained. Specifically in the first well the water cut was reduced from 71% to less than 1% (0.9%). In another well the water cut was reduced from 72% to 3.4%. In all these cases the oil production was significantly increased.
In addition to the incremental oil gain there is a big reduction in the cost of lifting and handling of unwanted water production resulting in achieving great economic benefits.
The post-job analysis allowed further optimization of these processes, which are facilitating similar applications in the future.
