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Friday, November 22, 2019
Invictus Energy has received the geochemical analysis results from its recent outcrop source rock field sampling program carried out in July 2019 in the Cabora Bassa Basin to the west of its SG 4571 permit. The analysis was conducted by GeoMark Research in the USA. A total of 19 samples were obtained for source rock analysis, with 7 of these samples undergoing saturate/aromatic (SARA), biomarker and isotope analysis.
The new program of outcrop sampling and geochemistry analyses has provided the Company with a cohesive RockEval and extract SARA/isotope/biomarker database, and has allowing for source rock facies and maturity interpretation and correlation with equivalent parameters from the existing database; and subsequently has expanded confidence in the source rock presence and quality.
The analysis confirms at least two source rock facies are present in the Cabora Bassa Basin, in the Mkanga Formation (Permian age) which consists of a high-quality oil prone lacustrine source rock interbedded with good quality gas and liquids source rocks; and the Angwa Alternations Member (Triassic age) consisting of good quality gas and liquid (condensate and potentially light oil) prone source rock.
The Mkanga Formation has present day Total Organic Content (TOC) values up to 40% and Hydrogen Index (HI) up to 380. whilst the Alternations Member of the Angwa Formation has TOC values up to 35% and HI up to 290. The TOCaverageis well above the recommended thresholds of 0.5 and 2.5 weight % of gas and oil generation respectively and confirms the ability of the source rock to generate significant quantities of hydrocarbons.
The source rock analysis also correlates with data from other African and West Australian Basins and suggests affinity with oil and gas prone source rocks from Madagascar, Ethiopia, Tanzania, Seychelles, Uganda and Perth Basins where billions of barrels in place and multiple TCF gas volumes have been discovered (see Figure 1). The calculated vitrinite reflectance (%Ro) and TMax data from RockEval suggests the majority of samples from outcrop are immature for hydrocarbon generation and expulsion (at surface), indicating the sampling locations on the flanks of the basin have undergone minimal burial and uplift; this is consistent with the rift-sag model of basin development.
However, three new samples from the Permian aged Mkanga Formation have calculated %Ro sufficient for hydrocarbon generation, with the geochemical analysis of these samples additionally indicating the presence of generated liquids. Extrapolation of these maturities into the subsurface of the basin suggests therefore that these source rocks identified in outcrop will have generated and expelled hydrocarbons deeper in the basin.
Invictus Managing Director Scott Macmillan commented: “The new RockEval geochemistry data has provided evidence that the source rock sequences present in the Cabora Bassa Basin possess good to excellent gas and liquid potential, comparable to ones in Africa and West Australia which host multi-billion barrel oil and multi-TCF gas discoveries. The reprocessing of the seismic data has generated higher resolution imagery, particularly near surface on the flanks of the Chewore Inliers, to the west of SG 4571, where the source rocks samples were collected from surface.
“The enhanced seismic imaging obtained has enabled the outcrop source and reservoir sequences to be mapped into the subsurface with greater confidence as well as providing a favourable view of the timing of two major episodes of generation of hydrocarbons into the multiple traps in the basin. The location of the source rock directly beneath reservoir positions them to charge the primary Upper Angwa Alternations Member target as well as shallower horizons in the Pebbly Arkose, Forest and Dande Formations. There is potential evidence of this shown by the seismic amplitude anomalies that conform to structure.”
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