Abstract
Shushufindi is the largest field in the Oriente Basin of Ecuador that was discovered by Texaco in 1970. It has produced about one billion barrels of oil over a period of 30 years. Early in the life of the field, peripheral water injection was implemented and was discontinued in 1999 based on the results of a previous reservoir simulation study carried out in late 90’s. Currently, the field is producing significant amount of water under very active water drive mechanism. The field consists of three main stacked reservoirs: Basal Tena, U and T and have produced from about 185 completions. This paper is focused on the reservoirs U and T. Historically, most of the wells in the field were produced commingled from these two reservoirs. This paper presents the results of an integrated reservoir study that was performed to optimize the field performance for effective reservoir management.
A 3D reservoir simulation model was constructed to optimize the performance of the field and to find opportunities to increase oil production. A successful history match achieved helped understanding the reservoir behavior and field performance. Since many wells produced commingled from the reservoirs U and T, dynamic fluid allocation was also performed by means of full-field history matching process. Distribution and location of remaining oil after accounting for the incremental oil recovery due to the workover wells helped delineating the locations of infill and step-out wells to increase production.
The results showed that reservoir pressure behavior was very erratic in both U and T reservoirs. However, the level of scatter was more pronounced in Reservoir U than in Reservoir T. Observed reservoir pressure trends seem to follow the channels observed from 2D seismic especially in reservoir U. However, local changes in the pressure trends could have been caused by the water injection. Some observations from the reservoir performance evaluation suggest that the erratic pressure behavior could also be attributed to the change in the formation compressibility due to fluid withdrawal and water injection.
The results also show that the effect of peripheral water injection was very limited and infill water injection could improve sweep efficiency of the reservoirs.
