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Thinking and Methodology Leading to a Major Sweetspot in Tight Sands - A Deep Eocene Misoa Sands Discovery

Chatellier, Jean-Yves D.1; Leon, Freddy 2; Sarzalejo, Sabrina 3; Perez, Renee 6; Hague, Paul 4; Wilpshaar, Martin 5
1 Talisman Energy Inc, Calgary, AB, Canada.
2 Partex Oil and Gas, Lisbon, Portugal.
3 McGill University, Montreal, QC, Canada.
4 Sarawak Shell, Miri, Malaysia.
5 Dutch200, Amersfoort, Netherlands. (6) Geochemical Research and Engineering Inc., Calgary, AB, Canada.

The methodology and thoughts that led to the discovery of the giant “Tomoporo-Profundo” Field will be reviewed to outline the power of a multidisciplinary integration associated with a 4-D diagenetic modelling. Our previous work in Lake Maracaibo demonstrated that very high porosity and permeability at great depth were likely linked to an early oil migration along a fault system. In Zulia Oriental, located east of Lake Maracaibo, deeply buried thick sandstones sequences were present but porosity was apparently absent.

The integrated work combined seismic with sedimentology, structural geology and geochemistry. The data comprised cores from a few wells and scattered 2D seismic lines. Vitrinite data was available for each of the 20 existing wells and gave us a good understanding of the basin burial history.

We generated predictive maps of various geological parameters for each horizon through time. Porosity evolution through time was calculated for each interval of interest in 9 hypothetical wells. One 2-D seismic line strongly indicated an early compression activity (Late Eocene) in an area close to a major fault that extends to the west to a short lived oil kitchen (Oligocene). The porosity destruction by quartz cement growth was thought to have stopped with the hydrocarbon filling the structural trap; implying the possible existence of a deeply buried “island” of sandstones with some 25% porosity among otherwise very tight sandstones.

A 3-D seismic was acquired on the prospective area with a subsequent discovery of a giant oil field; the “Tomoporo-profundo” Field.


AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009