Browsing by Author "Chaouchi, Rabah"

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    Analysis and interpretation of environment sequence models in Hassi R’Mel Field in Algeria
    (2009) Baouche, Rafik; Nedjari, A.; Eladj, S.; Chaouchi, Rabah
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    Facies analysis of triassic formations of the Hassi R’Mel in southern algeria using well logs : recognition of paleosols using log analysis
    (2009) Baouche, Rafik; Nedjari, A.; El Aadj, S.; Chaouchi, Rabah
    Well logs are essential in the study of geological formations, in terms of taking into account the nature and the structure of the formations, as well as the sedimentary processes. Qualitative and quantitative interpretations of well logs respond to a sedimentologic need as well as the establishment of lithological columns, according to the response to logging tools. In this study, electrofacies have been defined by manual well-log analysis of ten surveys of Triassic formations in the Hassi R'Mel area of Algeria. The data thus obtained were then matched with sedimentary facies defined by core analysis. The results obtained during the facies analysis made it possible to define ten electrofacies (sands, shale, dolomite, and evaporite, as well as the presence of andesite and clay). The model obtained by the Petrolog software was also developed and tested on other wells. A semi-automatic data processing was then carried out on seven other wells.Our aim is to highlight the added value of this integrated regional-scale to reservoir-scale approach in identifying nearfield exploration potential and additional recovery opportunities in producing reservoirs. Based on this aim, we emphasise the following points using our facies modelling: (1) improved definition of deposition within and between reservoirs, (2) development of regionally sedimentological models for reservoir intervals (the Hassi R’Mel Formations), and (3) recognition of paleosols from well log analysis and controls on reservoir architecture and their links to the Triassic Province of Algeria
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    Geomechanical modeling to assess the injection-induced fracture slip-potential and subsurface stability of the Cambro-Ordovician reservoirs of Hassi Terfa field, Algeria
    (Elsevier Ltd, 2024) Benayad, Soumya; Sen, Souvik; Baouche, Rafik; Mitra, Sourav; Chaouchi, Rabah
    The in-situ stress state and the distribution of the critically stressed fractures have significant implications on optimum wellbore placement, production enhancement, fluid injection, and induced seismicity which largely influence the reservoir management strategies. This study presents a comprehensive geomechanical modeling to infer the likelihood of shear slippage of the optimally oriented weak planes in response to water injection in the deep Paleozoic oil reservoirs from the Hassi Terfa field, central Algerian Sahara. The ‘B-quality’ compressive failures, i.e., breakouts from the acoustic image log indicate the maximum horizontal stress azimuth as N114°E. The inferred in-situ stress magnitudes indicate a strike-slip tectonic regime in the study area. The reservoir is generally tight (porosity <8 %, permeability <0.4 mD) due to extensive silica cementation, however pre-existing closed to partially open natural fractures of variable geometries are identified on cores, thin sections, and image logs. The stress-based slip assessment indicates that none of the fracture geometries is critically stressed and hydraulically conductive at the initial reservoir stress state. The onset of slip on the critically oriented vertical fractures can initiate at 1200 psi of fluid injection at the reservoir level of ∼3500 m. The E-W to EES-WWN oriented fractures, parallel to the maximum horizontal stress azimuth, have a higher likelihood of being critically stressed during injection and therefore can contribute to the permeability enhancement. We restrict the practical injection threshold at 3000 psi, which can create tensile failures on the shale caprocks. We infer that the NE-SW and NNE-SSW striking, steeply dipping fractures and regional faults being perpendicular or at high angles to the regional maximum horizontal stress azimuth, are the most stable ones and therefore, less likely to slip within the practical injection limit.
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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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    Sedimentological characteristics and reservoir quality prediction in the Upper Ordovician glaciogenic sandstone of the In-Adaoui-Ohanet gas field, Illizi basin, Algeria
    (Elsevier, 2019) Benayad, Soumya; Ysbaa, Saadia; Chaouchi, Rabah; Haddouche, Omar; Kacimi, Aymen; Kaddour, Hichem
    The Upper Ordovician glaciogenic deposits are thought to have an important quantity of hydrocarbon across North Africa. Insight is provided about the IV-3 reservoir unit in the In-Adaoui-Ohanet field in the Illizi basin of south-east Algeria. The aim is to: 1) describe the lithofacies; 2) interpret the depositional environment; 3) describe the petrographic characteristics; 4) investigate the petrophysical properties; and 5) perform a biostratigraphic analysis of the unit IV-3 reservoir (Upper Ordovician) in the In-Adaoui-Ohanet field based on the core description and samples collected from the well IA-115. Lithofacies described in the study area are MT1, MT2, MT3, MT6, and MT9. Subglacial tillite is the depositional environment associated with lithofacies MT3, MT6, and MT9. These lithofacies are thought to be deposited medial to a distal fan, whereas lithofacies MT1 and MT2 are thought to be deposited in high-energy flows. Acritarch and Chitinozoan species are the most common biozones described in the study reservoir and they are thought to be affiliated with an Upper Ashgilian stage. Petrographic analysis shows that the study reservoir unit is formed by fine to coarse-grained sandstone. Quartz is considered to be the principal framework mineral (mean, 56.30%). Cementing minerals observed in this reservoir unit are quartz and carbonate. From a compositional point of view, the unit IV-3 reservoir in the In-Adaoui-Ohanet field is predominantly formed by quartz arenites, which are considered to be mature. Additionally, the tectonic setting of these arenites is most likely associated with a passive margin origin. The emphasis throughout this study is on the role of factors such as permeability, carbonate cement, and quartz overgrowth on the reservoir quality of unit IV-3 in the In-Adaoui-Ohanet field. The quality of this reservoir unit is highly influenced by the quartz overgrowth and pores that are plugged by carbonate cement, which dramatically reduces the pore network. An enhanced porosity was observed only in the MT3lithofacies (up to 22.3%). Additionally, from an economic point of view, the study reservoir unit is classified as a tight gas-bearing reservoir
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    Unconventional resources in Algeria : appraisal result from the Hamra quartzite reservoir
    (Springer, 2013) Benayad, Soumya; Park, Young-Soo; Chaouchi, Rabah; Kherfi, Naima