Tertiary Petroleum Systems around the World: Sediment Controls from Regional GIS Studies

By

William G Dickson¹, Janice M Christ², Al Danforth³, Ian W Somerton⁴, James W. Granath⁵

(1) DIGs, Stafford, TX (2) J-SEA Geoscience, The Woodlands, TX (3) Consulting Exploration Geologist, Houston, TX (4) GETECH, Leeds, West Yorkshire, United Kingdom (5) Granath & Assoc, Houston,

 This story began in the South Atlantic and progressed around SE Asia. A small global new ventures team began combining potential field and other data using GIS (Geographic Information Systems) software. The approach provides such utility that it deserves a new name, here dubbed EGIS (Exploration Geology Information System). We show examples in Tertiary sequences in five basins (Congo Fan, Angola; Baram Delta, NW Borneo; Campos Basin, Brazil; Pearl River Mouth Basin, China; Niger Delta, Nigeria) where striking correlations were observed between geologic features that control sedimentation and signatures of potential field attributes.

The EGIS environment enabled faster, more precise interpretations and digital presentation of results. Long-recognized features not previously imaged in their entirety were reinterpreted, realigned and extrapolated, due to improved data coverages. The data signatures in map view drew unexpected geologic inferences using simple tools and basic concepts.

We first reinterpreted extents of continental, oceanic and proto-oceanic crust with implications for hydrocarbon maturation. Investigations of crustal type and limits revealed surprising correlations between gravity imagery and reservoir and source distribution. This paper illustrates:

- inter-raft sediment pathways, post-salt depocentres and unconfined basin floor fans, Congo Fan - basement control on Oligocene fans, bypass zones and source pod locations, Campos Basin - correlations between discovery trends, toe thrust belts and basement structure, Niger Delta - projections of base of slope/basin floor fans offshore NW Borneo & Pearl River Mouth Basin

The story continues as more detailed data advance our understanding and the simple tools empower improvement in both techniques and interpretations.