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Analysis of Petroleum Charge Scenarios – An Example from the Norwegian Barents Sea

Michael Cheng1, Laura Lawton1, Dave Burnett1, Will Parsons1, and John Guthrie2
1Hess Limited, Level 9, The Adelphi Building, 1-11 John Adam Street, London WC2N 6AG
2Hess Corporation, One Allen Center, 500 Dallas Street, Houston, TX 77002

Petroleum systems analysis is now routinely applied in many oil and gas companies for regional and prospect scale geological evaluations for exploration. Analysis of charge adequacy and scenarios - integral to petroleum systems analysis - often carries uncertainties for a variety of reasons. For example, poor characterization of source rock variability and/or inaccurate mapping of thermal stress related to uplifting and erosion. In this paper we present a case study of regional-scale charge scenario analysis designed to constrain uncertainties for an area in the Norwegian Barents Sea.

The Norwegian Barents Sea is a prolific petroleum province with multiple proven source rocks and reservoirs. Within this province significant volumes of gas and condensate have been discovered, while large volume of oil was discovered only in the Snohvit field. However, the recent oil discoveries at Goliat (2000) and Nucula (2007) present a different aspect of the petroleum systems complexity in the Barents Sea.

To help us understand such complexity and investigate for viable petroleum charge scenarios for Goliat & Nucula as well as regional evaluation of prospect charge adequacy, we conducted an integrated petroleum systems analysis. Our analysis has two important components: 1) we characterized source rocks for ultimate expellable potential (UEPs) using data from a large number of wells and built a 3D thermal history model (via ZetaWare Trinity) using regional seismic maps of key horizons; and 2) we integrated results of a regional geochemistry analysis of reservoir fluids and fluid inclusion stratigraphy analysis for multiple wells.

We applied the regional-scale 3D Trinity model, which incorporates regional estimates of erosion and is constrained by observed bottom-hole temperatures, for charge scenario and fetch history analysis. Using known pressure and temperature, fluid and reservoir properties at the Snohvit and other discoveries (oil and gas API gravities, column heights, net-to-gross, and HC in-place volume), we then applied prospect-scale Trinity model for multi-stage (pre and post- uplift) PVT considerations. Such PVT considerations provided us a unique calibration to our charge scenario/fetch history analysis. This integrated regional analysis shed important insights for us to the likely charge scenarios for Goliat and Nucula and it provided us a confident risking for prospect charge scenarios.

 

AAPG Search and Discovery Article #90091©2009 AAPG Hedberg Research Conference, May 3-7, 2009 - Napa, California, U.S.A.