Publications Scientifiques

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Author: search.filters.author.Sen, SouvikHas files: No

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    Modeling In-situ tectonic stress state and maximum horizontal stress azimuth in the Central Algerian Sahara – A geomechanical study from El Agreb, El Gassi and Hassi Messaoud fields
    (Elsevier, 2021) Baouche, Rafik; Sen, Souvik; Chaouchi, Rabah; Ganguli, Shib Sankar
    Central Algerian Sahara hosts many prolific hydrocarbon accumulations in the Paleozoic successions. In this work a contemporary stress field of the Saharan platform has been evaluated using the dataset from recently drilled wells in El Agreb, El Gassi and Hassi Messaoud fields. A pore fluid pressure gradient of 0.56 PSI/feet is interpreted from the in-situ measurements in the Paleozoic reservoir units. Vertical stress (Sv) modeled from the bulk-density data indicates an average of 1.02 PSI/feet gradient. Rock elastic property-based approach is employed to model the magnitudes of minimum (Shmin) and maximum horizontal stress (SHmax) components, which were calibrated with leak off test/minifrac and breakout widths, respectively. Paleozoic stress profiles reveal Shmin/Sv range of 0.74–0.84, while SHmax/Sv varies between 1.1 and 1.33. Subsurface stress distribution indicates that the present-day stress field in the Saharan platform is principally strike-slip faulting (SHmax > Sv > Shmin). A cumulative 1490 m of B-D quality wellbore breakouts, inferred from the acoustic image logs, suggest a NW-SE/WNW-ESE SHmax orientation, which is parallel to the absolute African plate motion and Africa-Eurasia plate convergence direction, implying ridge push force to be the dominant contributor to the tectonic stress field. Mean SHmax orientation shows slightly anticlockwise rotation (126◦N to 144◦N) from south (El Agreb) to north (Hassi Messaoud field). Inferences are discussed regarding the fault slip potential and hydrocarbon reservoir development.
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    Petrophysical, geomechanical and depositional environment characterization of the Triassic TAGI reservoir from the Hassi Berkine South field, Berkine Basin, Southeastern Algeria
    (Elsevier, 2021) Baouche, Rafik; Sen, Souvik; Ganguli, Shib Sankar; Hadj Arab, Feriel
    An integrated knowledge of the sedimentological data, petrophysical and geomechanical characteristics significantly enhances the understanding of the reservoir properties, leading to a reliable subsurface modeling. This work presents a comprehensive reservoir assessment of the prolific Triassic Argilo-Gréseux Inférieur (TAGI) sandstones of the Hassi Berkine South (HBNS) field, Southeastern Algeria. The Lower Triassic producer appears to be laid down on the Late Devonian erosional surface (Hercynian unconformity) in a fluvial depositional system. Based on the sedimentary structures, a fluvial depositional environment is deciphered from cores. Lateral and vertical disposition of the channel and floodplain deposits from regional well log correlation infers a shift of depositional regime from braided in the SW to meandering in the NE direction. Two distinct reservoir rock types (RRT) are interpreted from core-based petrophysical assessment. RRT1 is composed of macro-megaporous medium to very coarse grained amalgamated channel sandstones and yields the best reservoir attributes, while the mesoporous fine grained RRT2 translates to impervious to poor reservoir quality. RRT1 channel sands are found to be laterally continuous, while the fine grained crevasse splay sands corresponding to RRT2 are laterally discontinuous, thus making them difficult to correlate field wide. Rock-mechanical property-based in-situ stress estimates suggested a normal to strike-slip transitional (Sv ≥ SHMax > Shmin) stress state in the TAGI Formation. Direct measurements indicate that the TAGI reservoir had an initial pore pressure gradient of 11.08 MPa/km and is presently depleted by 2.1–2.5 MPa. A stable depletion stress path value of 0.57 is inferred considering a pore pressure-minimum horizontal stress coupling. At the present-day depletion rate, normal faulting is unlikely to have happened at the TAGI reservoir level and it can be depleted by another 25 MPa before inducing any production-induced reservoir instabilities