Title : Fracture system analysis and optimization of oil recovery In the Chinguetti offshore reservoir
Abstract:
The MSGBC basin (Mauritania, Senegal, Gambia, Guinea-Bissau, and Guinea-Conakry basin), which is located in the North West Africa Atlantic Margin (NWAAM) (Figure 1 ), is a passive margin basin that was developed in response to the opening of the proto- Central Atlantic Ocean. It is tectonically controlled and highly dissected by a set of highly complicated structure (Dahmane et al, 2025). Fractured reservoirs are among the most important sources for enhancing global oil and gas production. Accurate fracture characterization is a critical step in modeling fluid flow in naturally fractured reservoirs (Al-Rubaye et al., 2021; Cao et al., 2025; Liao et al., 2025; Jinyang et al., 2025).
The Chinguetti Field, located offshore Mauritania in water depth, is a faulted anticline overlying a salt diapir, with Miocene turbiditic reservoirs between 2200–2800 m TVDss and pressures of 3500–4200 psig. The reservoir exhibits high structural complexity and compartmentalization due to extensive faulting. Initial production peaked at 75,000 BOPD in 2006 but declined sharply due to limited connectivity and reservoir heterogeneity (Dahmane et al 2025). The Field structure is a faulted domal anticline developed over an underlying salt diapir. The faults are radial and concentric, dominated by a complex, roughly east-west, main fault that appears to be the oldest. The faulting of the field has produced compartmentalisation and perched fluid contacts across the structure and at least three different oil–water contacts (OWCs) are interpreted. Locally the sediments are controlled by structure, a combination of salt diapir growth, salt withdrawal in the rim synclines and the associated growth faulting in the dome.
Fracture characterization in the Chinguetti Field reveals significant dysconnectivity caused by complex faulting within Miocene aged reservoirs. These insights are highly relevant to nearby offshore fields such as Tiof, Banda and TEVET, which also target Miocene reservoirs and may face similar connectivity challenges. In summary, it can be concluded that majority of the oil producers have already experienced water breakthrough from injected water, based on the observation from both the high watercut status in the respective wells and the results from the tracer injection. In essence, the injected water is practically a recycling stream and continuously sweeping small remaining oil in the path between the water injector and oil producer. Different chemical tracers were injected into each layer of each well to help identify injection water breakthrough. The injection tests indicated that injection BHP exceeds fracture pressure and the fracture systems generated were consistent with an unconsolidated heterogeneous layer and channelised reservoir sequence.
The study provides a valuable framework for understanding and managing fractured systems in future developments. This study aims to: analyze Faults fractures-controlled trapping mechanisms using 3D seismic profiles to define the structural Control of the reservoir and evaluate fracture/Faults network connectivity to identify high-permeability and high-porosity zones for the optimization of production in such fractured reservoirs.
Key words: MSGBC, GTA, FMI, AVO, Traps, production optimization, fractured reservoir.
