Production Results from Levee-overbank Turbidite Sands at Ram/Powell Field, Deepwater Gulf of Mexico

Clemenceau, G.R., Jason Colbert, and Dennis Edens, BP-Amoco, Deepwater GOM, Houston TX.

Abstract

The Ram/Powell Field is in the northeastern Gulf of Mexico in 3200 ft of water. BP-Amoco has a 31% WI in the ~300 MMBOE field, which is currently producing at 45000 BOPD and 270 MMCFPD from four middle Miocene reservoirs. These reservoirs are stratigrap hically trapped within various facies of an unconfined submarine fan system.

One of the reservoirs, the "L" sand which contains ~18% of the field reserves, is trapped entirely within the levee-overbank facies of a channel-levee system, according to log, core, and 3D seismic interpretation. The "L" sand is divided into proximal and distal elements based on net sand percentage and bedding architecture. The proximal levee averages ~60% net sand and has bed sets of increasing and decreasing dip patterns, whereas the distal levee averages ~27% sand but constant low angle dips. Conven tional core data from this thin-bedded and laminated sand indicate porosities of 15-32% and permeabilities of 20-1000mD. The presence of interbedded silts and shales within a complex architecture, as observed in core and dipmeter data, is expected to red uce inter-well connectivity and therefore decrease well rate and recovery.

Well rate and recovery performance are difficult to predict from levee-overbank facies sands because their sub-seismic complexity is hard to understand using limited well and core data. Simulation of such complicated bedding geometry is also difficult, requiring gross up-scaling of potentially important details. Recent development drilling and production data from the Ram "L" sand have provided a better understanding of how levee-overbank reservoirs can perform.

The "L" sand reservoir is completed with a single 2500 foot near-horizontal well, located in the proximal levee facies. Well results show that pressure transient estimated permeability from the "L" sand completion is ~35 mD, considerably less than the con ventional core average of ~300mD. The lower reservoir permeability, measured from the producing well, may be due to baffling of the high permeability thin sand beds as seen in the logs and cores. However, the peak production rate of 105 MMCFD x 9600 BCPD exceed expectations. Production results from the horizontal well and wireline pressure data from other wells show that the entire 4000 acre reservoir is in communication. One explanation for the better than expected connectivity is the suspected presenc e of sand-on-sand cut and fill architecture as suggested by cores, dipmeter logs, and outcrop observations.