Brutus Late Life Redevelopment: An Integrated Field Study using Legacy 4D Seismic and Geochemical Analysis

Broussard, Robin (Shell Upstream Americas) | Jimenez, Juan (Shell Upstream Americas) | Leenaarts, Elise (Shell Upstream Americas) | Lyell, Sharon (Shell Upstream Americas) | Stammeijer, Jan (Shell Upstream Americas)

OnePetro 

Summary

Connectivity between reservoir compartments in the Brutus Field is difficult to predict despite extensive availability of conventional 3D seismic, and historic production and pressure data, resulting in risk and uncertainty in planning future late-life development wells. It is because of this that more sophisticated tools are needed to unravel the complex structural and stratigraphic framework in this mature field, leading to an integrated approach to field development using both qualitative legacy 4D seismic data and geochemical fingerprinting data obtained as part of the reservoir surveillance activities. The 4D signals observed on the time lapse analysis of a 2012 ocean bottom node (OBN) dataset compared to a pre-production, 1999 narrow azimuth (NAZ) streamer dataset appear consistent with production, pressure and geochemical data. This integrated interpretation approach supports the probability of several remaining undrained reservoir compartments that are being targeted in the upcoming Brutus drilling campaign. One of these compartments, the J2 Reservoir U2 fault block, will be the focus of this paper.

The integrated results of the legacy 4D, production, pressure, and geochemical data support the interpretation that the J2-RU2 block is an undrained/poorly drained compartment, thus lowering the subsurface risk of drilling a development well here.

Introduction

Brutus Field, located in Green Canyon blocks 158 and 202 in the Gulf of Mexico, is a mature oilfield producing since 2001 from Pliocene and Pleistocene reservoirs. The field is located along the eastern flank of a northwest-southeast trending salt ridge that formed during Late Pliocene to Early Pleistocene times in direct response to sediment loading and associated faulting. The sediments that accumulated within the resulting Brutus mini-basin have been strongly influenced by episodic salt withdrawal and syn-sedimentary faulting. Brutus’s most prolific and deepest reservoir is the Late Pliocene J Sand, which accounts for about two-thirds of the field’s production. The location map is shown on Figure 1.