Exploration Insights March 2020

18 | Halliburton Landmark Exploration Insights | 19 85 74 11 0.93 1.10 0.17 75 145 70 Top of Oil Window (km) 2.40 1.60 0.80 (33%) Top of Gas Window (km) 3.55 2.40 1.15 (32%) Vitrinite Reﬂectance (Ro%) Peak Hydrocarbon Expulsion (Ma) Table 2> Selected values between deep and shallow offshore pseudo well models at present day. The relative change in percent is shown in brackets. later hydrocarbon expulsion timing for the Middle Jurassic source rocks provides a longer window for traps to form, leading to a decreased risk for exploration in the deeper offshore. Cretaceous CONCLUSIONS Based on the hydrocarbon source rock maturity results from the 1D basin models, it is unlikely that there will be potential for Cretaceous source rock plays. However, the source rock depth was never varied in the 1D models, and varying this input could have generated hydrocarbon potential from the Cretaceous source rock. Recent success on the East African margin has sparked exploration interest in the conjugate western Madagascan margin. Using data and insights from the Neftex Insights portfolio, integrated and processed in Permedia petroleum systems modeling software, we have assessed the source rock maturity of the Morondava Basin offshore western Madagascar. LICENSE BLOCK TARGETS — WHERE IS OIL OR GAS PREDICTED? Triassic and Jurassic rifting episodes affected both the East African and western Madagascan margins. The East African margin generally has The license blocks extend from the shallow offshore in the north-eastern Morondava Basin to 0 Deep Offshore IMM Oil Gas 0 Fine-grained deep marine siliciclastics Deep marine carbonates OM 1 Gas OM Fine-grained deep marine siliciclastics 200 Late 180 Early Triassic 160 Mid Jurassic 140 Late Fine-grained deep marine siliciclastics 3 Organic-rich carbonates Fine-grained shallow marine siliciclastics 4 Continental sediments 1 Vitrinite Reflectance [%R o ] Minimum 5 Best Estimate Fine-grained deep marine siliciclastics 3 Organic-rich carbonates 4 Fine-grained shallow marine siliciclastics 5 6 0.1 Continental sediments 1 Vitrinite Reflectance [%R o ] Maximum Potential Range 80 60 Late Pal. 40 Eocene Paleogene 20 0 Olig. Miocene Pl. Time (Ma) Neog. Q. Oil Oil Event Reservoir Deposition Deep Oﬀshore Expulsion Gas Gas © 2020 Halliburton Shallow Oﬀshore Expulsion Figure 5> Select petroleum system events and the best estimate of the hydrocarbon expulsion timing for the Middle Jurassic source rock in the deep (Pseudo Well D) and shallow (Pseudo Well F) offshore. The reservoir deposition and trap formation timing data were taken from the Neftex ® PlayFinder Application greater source rock maturity, in part due to the greater overburden produced by the major deltas in the region, which are not as pronounced on the western Madagascan margin. Although both regions experienced the same major tectonic events, the sedimentary processes differed, which resulted in less sediment deposition and, thus, a decreased hydrocarbon maturity along the western Madagascan margin relative to the East African margin. This means that the western Madagascan margin is likely to be more prospective for oil than the gas-dominated conjugate East African margin. The Middle Jurassic source rock represents the source rock with the lowest exploration risk. With more calibration data, such as vitrinite reflectance or borehole temperature measurements, the tectonic events could have been varied as inputs to the 1D basin models and served as a tool to better understand the tectonic evolution model for the region hosting the basin. The hydrocarbon potential in the offshore Morondava Basin looks positive from a source rock perspective. Now, further work is required to assess the reservoir and trap potential of the offshore. ACKNOWLEDGMENTS The tectonic events of the region were incorporated with the 1D basin models to estimate the source rock maturity throughout the Morondava Basin. Results suggest that the shallow offshore is likely to be gas prone, and the deep offshore is likely to be oil prone. West Pseudo Davie Well D 0 East Pseudo Well F Ridge Madagascar License Block Boundaries 2 4 J K K Cretaceous J J Jurassic T T 8 J Triassic Immature Oil Window T Gas Window K 0 2 K Cenozoic K 6 The authors thank Halliburton Landmark for the support provided through the Science and Technology for Exploration and Production Solutions (STEPS) program. This work presents the results of STEPS project NF06 - Can the Pseudo Well E Precambrian Basement 5 100 Cretaceous Volcanics 2 120 Early Trap Formation Deep marine carbonates Fine-grained deep marine siliciclastics 2 Oil 1 Fine-grained deep marine siliciclastics 0.1 Shallow Offshore IMM 220 4 T K 6 50 km J J T Overmature T Transformation Ratio (%) 240 Mid Depth the deep offshore in the west (Figure 1). Based on the drilled wells with vitrinite reflectance data and modeled pseudo wells in the proximity of the license blocks, there is potential for oil and gas accumulations in this area. The north-eastern license blocks in the shallow offshore are a promising target for gas plays, while the western blocks deeper offshore are more likely to be oil prone. The range in the ages of the reservoirs that could have been charged is greater for the deep offshore, as hydrocarbon expulsion occurred later than in the shallow offshore. Thus, younger reservoirs could have been changed in the deep offshore (Figure 5). Deep Shallow Oﬀshore Oﬀshore Diﬀerence Parameter 8 Source Rock: K Cretaceous J Jurassic T Triassic © 2020 Halliburton Figure 4> Minimum, best, and maximum vitrinite reflectance estimates for the deep (Pseudo Well D) and shallow (Pseudo Well F) offshore. Figure 6> Modeled cross-section, including pseudo wells D-F, with a maturity overlay under the best estimate conditions. Line location is taken from Tari et al. (2017), and can be seen in Figure 1.

Exploration Insights March 2020 | Page 18