Published: 09/14/2020
Published: 09/14/2020
Located approximately 60 km off the coast of Mexico in the Sureste Basin, the Zama Field is thought to be one of the world's largest shallow-water oil discoveries. Initially identified as a three-way dip structure sealed against salt, the field's massive stacked turbiditic sands are overlain by a thick hemipelagic shale. In the first exploration well, sampling was limited because of well complexities and the loosely consolidated reservoirs. Without multiple representative fluid analysis and samples, reservoir connectivity could not be assessed. This had to be addressed during appraisal.
The Ora intelligent wireline formation testing platform leverages new architecture and metrology to apply focused sampling with a 3D radial probe for acquiring pure fluid samples and conducting DFA. The wideband downhole pumps precisely govern their broad dynamic range with automated flow management, which enables the controlled low-pressure drawdown necessary to prevent sanding in unconsolidated reservoir intervals. The real-time DFA guides the sampling process, identifying additional depth intervals that require characterization for assessing reservoir continuity through application of the new discipline of reservoir fluid geodynamics (RFG).
"Talos was very interested in bringing the latest technology to our appraisal program at Zama. The new Ora platform allowed us to achieve our objectives of collecting very clean samples throughout the reservoir to enable highly reliable advanced fluid studies."
—Loren Long, Vice President–Mexico, Talos Energy
More than 30 pressure-compensated high-purity fluid samples were efficiently collected with the Ora platform at multiple depths in station times of only 1 to 2 hours. The real-time optical density measurements of different zones in the two wells confirmed reservoir continuity. The RFG analysis also indicated that the multiple stacked sands were laterally connected.
Subsequent laboratory analysis of the samples confirmed the determination of lateral connectivity. Petroleum geochemistry analysis also corroborated the DFA fluid gradient and RFG asphaltene concentration gradient models to provide further insight on the timing of migration and reservoir charging. Interpretation of geological image logs and subsequent full-core analysis were consistent with gradient analysis, with further confirmation of the predicted lateral connectivity provided by a multizone well test.
Talos Energy Inc. employed the Ora intelligent wireline formation testing platform for downhole fluid analysis (DFA) and sampling in two complex wells, enabling conducting reservoir fluid geodynamics to confirm connectivity in unconsolidated sands that could not be sampled with conventional technology.
