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The Connection Set Approach: Better Faults' Representation for More Robust Production Forecasts

3rd Prize - Best Innovators 2020

A project presented by Claire Fournier, Merouane Abbad, Magali Grangier, Alejandro Rodríguez Martínez et Ismail Zine-El-Abidine

claire_fournier_exploration_production_total
Claire Fournier

Reservoir

The Connection Set approach provide a greater precision in the representation of faults for the dynamic modelling of reservoirs. This digital tool allows more flexible and faster workflows. Better decision making is enabled by more robust development base-case, thanks to better uncertainty management and risk evaluation. This technology – double patented by Total – is a performance booster for geoscientists and a competitive advantage.

The Connection Set Approach Unlocks New Potential For Simulation Models

Exploration & Production teams routinely deal with the increasing complexity of geological settings, for instance, highly faulted deep-water reservoirs. In such context, a finer understanding of the reservoir characteristics and behaviour is key to have efficient field development. In particular, the transmissibility of faults, and their role as barriers or drains in fluid flows, is a key uncertainty in reservoir simulation.

Our new approach based on the Connection Set language – a world first - allows the explicit representation and visualisation of interactions between couples of neighbouring cells. This is a crucial progress in the understanding of the dynamic behaviour of our simulation models.

Connection Set Approach - Best Innovators 2020 - Exploration & Production - Total

A more precise dynamic representation of faults

Through the Connection Set approach, flow is modelled by describing the network of faults as a set of cell-to-cell connections: a Connection Set. Indeed, given a reservoir simulation grid and a set of seismic surfaces representing faults, it collects all the couples of neighbouring cells whose centre-to-centre connection is intersected by any of the fault surfaces. During simulation, the Connection Set is used as a support to modify flow by assigning suitable transmissibility multipliers to each cell-to-cell connection. The multipliers may be adjusted to account for the local physical properties of both the fault surface and the grid cells.

This innovation unlocks an unprecedented precision and flexibility for dynamic fault representation. In fact, it naturally adapts to the stairstep modelling technique, resolving all the intrinsic issues of simulation keywords previously used to model flow across faults. In fact, unlike traditional keywords that were never intended to work with advanced gridding techniques like stairstep, PEBI or fully unstructured grids, Connection Sets are naturally well-suited to these new trends in reservoir modelling.

The Connection Set approach also enables the 3D visualization of faults and simulation results to a degree that was unconceivable until today. Reservoir engineers can now obtain a much better understanding and visual quality control of their models, , even beyond faults: the Connection Set approach works equally well for any other geological feature represented as a surface (horizons, bodies, channels…) and for any cell-to-cell calculation like transmissibility, pressure drop, phase by phase rate, consecutive cells volume ratio etc. Integrated geomechanical flow simulations are on the near horizon, and Connection Sets are up to the challenge with their natural adaptability to unstructured grids.

Connection Set Approach - Best Innovators 2020 - Exploration & Production - Total

A flexible, user-friendly tool integrated with Sismage-CIG

This innovation changes the way in which dynamic reservoir simulation models are approached.

  • New workflows enable faults and other geological features to be inserted, on the fly, into an existing reservoir grid, without the need to go through an expensive update of the reservoir model. In traditional workflows, such a time-consuming update was needed even before the impact of the changes could be assessed. This represents a revolution in modelling, eliminating what used to be a long, costly sequential process.
  • Increased flexibility and efficiency contribute to estimated timesaving (and therefore cost-saving) gains of up to 40%.
  • The tool improves risk assessment. It also makes it possible to rapidly deliver more robust development and resource scenarios.

The modelling process and interface language were developed in-house over six months by the reservoir team in Sismage-CIG, Total’s integrated geoscience platform. The user-friendly interface is now integrated as a plug-in within the tool. Continuous agile development is pursued by developers and users, ensuring a healthy and useful life to the tool. The Connection Set approach has already been successfully employed in two of our fields: Chissonga in Angola and Preowei in Nigeria.

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