The Future of 4D in the Nile Delta

By

 Robert Francis Marten¹, James A Keggin¹, Giles F Watts¹

(1) BP Egypt, Maadi,Cairo, Egypt

 4D or time-lapse seismic is now an accepted technology for reservoir management. There are numerous documented successes in oil reservoirs from the North Sea, Gulf of Mexico and elsewhere. The science behind the 4D technology is beautifully simple: as oil or gas is produced from the reservoir, the reservoir experiences pressure and saturation changes. Provided the magnitude of these changes is large enough, repeat seismic surveys over the field may be able to track flood fronts or recognize flow barriers, identifying bypassed pay and extending the life of the field.

While numerous 4D success stories can be credited to oil reservoirs, little work has been done on applying the technology to gas reservoirs. Although time-lapse effects are expected to be generally smaller in gas reservoirs, recent modeling studies show the effects should still be visible. Strongest effects are expected to be seen in shallow gas reservoirs with good quality 3D seismic datasets. This includes most of the Pliocene in the Nile Delta, where 14 Tcf of gas have been discovered, with current production from numerous fields. If 4D technology could be applied here, it could provide a great cost benefit by enabling the cost-effective management of gas reservoirs through field life.

This paper presents recent rock property work on BP Egypt’s Ha’py field, which suggests that time-lapse seismic may have be an appropriate technology for reservoir management. The commercial benefits are explored and some predictions made about the level of repeat seismic activity that may be justified in future years.