Darche, Gilles (Total SA) | Marmier, Rémy (Total SA) | Samier, Pierre (Total SA) | Bursaux, Romain (Total SA) | Guillonneau, Nicolas (Total SA) | Long, Jérôme (Total E&P Congo) | Kalunga, Hernani (Total E&P Angola) | Zaydullin, Rustem (Total E&P Research & Technology USA) | Cao, Hui (Total E&P Research & Technology USA)
We present a global simulation strategy of coupling reservoir and surface network models to manage production profiles of a deep-offshore field (West Africa) operated with a subsea development. This strategy allows a better consolidation of both short-term and long-term production profiles as compared to stacked standalone reservoir profiles.
The simulation study consists of 4 independent reservoir models, connected to surface facilities through a common subsea network. The first method uses loose external coupling between a new-generation commercial reservoir simulator and a commercial subsea network modeling package. It will be used to derive an optimal management of the network (network design, surface controls). This first coupling approach can also generate input data (pressure drops in network described by VLP tables) necessary for the second coupling approach, consisting in a fully coupled reservoir-surface simulator developed in-house, used to evaluate infill scenarios and to compute long-term production profiles.
These two coupling approaches bring their own value to the evaluation of the potential of the field.
The loose external reservoir-network coupling better manages surface constraints. It enables to design and to optimize the subsea network, accounting for the surface capacities. It also manages transient effects in the network, therefore enabling short-term optimization of the production. It will also highlight critical features (like pipe erosion, managed through the C-factor parameter) for the network.
However due to high TCPU and numerical instability, it is unsuitable for extensive sensitivity studies. For that, we use our in-house fully coupled reservoir-network simulator, with network description provided through the external coupling approach. These fully-coupled simulations, though using simpler network descriptions, are much faster and more robust, enabling to perform sensitivities on reservoir management, on infill well scenarios, in order to maximize long-term production profiles. We also developed new options in our in-house simulator to model the critical network features identified by the external coupling approach (like C-factor, fluid mixing, gas-lift optimization on risers).
Therefore, the use of these two workflows has enabled a full optimization of the field development, both The study has shown that these two technical coupling approaches are complementary, and bring better value to a field development when performed together. Furthermore, the external coupling approach identified the critical network features to be also managed in a fully-coupled reservoir-surface simulator, leading to new developments into this simulator (management of C-factor, fluid mixing, gas-lift optimization on risers).
The paper proposes a novel framework for the reservoir and surface facilities modeling. Our new approach benefits from the advantages of the two previous approaches: numerical stability/efficiency of the fully coupled approach and the workflow/accuracy of the separated approach.
Morel, Danielle (Total SA) | Al-Amrie, Omar (Total ABK) | Delattre, Eric (Total ABK) | Cordelier, Philippe (Total SA) | Greder, Hugues (Total SA) | Rivero, Mayela (Total US) | Romero, Carolina (Total SA) | Bursaux, Romain (Total SA) | Peltier, Sophie (Total SA) | Levitt, David (TOTAL SA, ADMA)
In 2014, Total performed a surfactant-polymer one spot pilot offshore to test the effectiveness of inhouse developed surfactant molecules to mobilize trapped oil. This paper describes the deployment of this pilot, as a key step of the derisking roadmap of chemical EOR under the harsh salinity and temperature conditions of Middle East carbonates. During several years of R&D and focused studies on this field of the Emirates, a surfactant polymer formulation has been developed able to achieve very low residual oil saturation at core level. The question of testing the formulation in the field has been addressed in parallel to the laboratory work, through extensive surface and subsurface integrated studies, in order to define which type of pilot would be the more suitable.
The paper addresses several aspects: Pilot type selection from a geosciences point of view and versus objectives and information provided: where, how many wells, time response, cost Monitoring needs: base line establishment, injection and production follow up, Surface issues related to the pilot in this offshore context: injection and production top side facilities Chemical logistics when part of the formulation is a R&D chemical, to be manufactured on purpose, and imported in due time, including the choice of premix versus on line mixing products Management of a pilot as a project but still with the specificities of derisking and qualifying a technology on a mature field (from preliminary study to project execution) Offshore concerns, with the added difficulty of a H2S environment
Pilot type selection from a geosciences point of view and versus objectives and information provided: where, how many wells, time response, cost
Monitoring needs: base line establishment, injection and production follow up,
Surface issues related to the pilot in this offshore context: injection and production top side facilities
Chemical logistics when part of the formulation is a R&D chemical, to be manufactured on purpose, and imported in due time, including the choice of premix versus on line mixing products
Management of a pilot as a project but still with the specificities of derisking and qualifying a technology on a mature field (from preliminary study to project execution)
Offshore concerns, with the added difficulty of a H2S environment
After a cautious analysis of the pros and cons, a one spot pilot has been sanctioned. The design of the pilot versus effective realization is provided, together with the decision tree that was constructed in order to face any operational issue. The paper emphasizes how a strong project management, and headquarters/operational team collaboration allowed completing a safe and successful pilot, ultimately achieving ultra low residual oil at the one spot scale.
The success of a pilot project is conditioned to the strict application of a rigorous methodology of study, validation, and execution, like any development project
In 2014, TOTAL performed two Single Well Tracer Tests (SWTT) to evaluate the remaining oil saturation in an offshore high temperature, high salinity carbonate reservoir. The SWTT method has proved to be a reliable way, when carefully programmed, to measure a representative remaining oil saturation without being impacted by near wellbore effects. The objective of these measurements was to evaluate the efficiency of a single well chemical EOR (CEOR) pilot by measuring oil desaturation.
Extensive in-house laboratory work was carried out by TOTAL to lay the foundation for the pre and post CEOR pilot SWTTs. A specific tracer injection skid was internally developed to ease the operations. Specific numerical work was performed to achieve robust designs and interpretations. These simulations, carried out in-house, took into account all major uncertainties highlighted by experimental work. Detailed results from the SWTT preparation phase will be described in the paper.
Results from the baseline SWTT interpretation evidenced excellent quality tracer profiles from the first test and high remaining oil saturation, improving our knowledge on the flooding pattern of this reservoir. Results from the post EOR SWTT showed again a clear response of a remarkable decrease in remaining oil saturation, proving the efficiency of the chemical formulation provided by TOTAL and the envisaged recovery mechanism. Interpretation of these Single Well Tracer Tests also allowed us to evidence a much lower than anticipated reservoir dispersion. These findings highlight the potential of EOR implementations in these carbonate formations.
Lessons learned from these two offshore SWTTs are discussed in this paper, such as the need for specific preparation to tackle the complexity of a high temperature high salinity carbonate reservoir in presence of H2S. TOTAL has shown that such operations can be performed in a strict timeframe while adhering to company safety rules. Careful interpretation of such results is mandatory to validate the success of the single well chemical EOR pilot.
Al-Amrie, Omar (ADNOC) | Peltier, Sophie (ADNOC) | Pearce, Adrian (ADNOC) | Abu-Dhabi, Total (ADNOC) | Al-Yafei, Arafat (ADNOC) | Morel, Danielle (Total SA) | Bourrel, Maurice (Total SA) | Bursaux, Romain (Total SA) | Cordelier, Philippe (Total SA) | Jouenne, Stephane (Total SA) | Juilla, Hugo (Total SA) | Klimenko, Alexandra (Total SA) | Levitt, David (Total SA) | Nguyen, Michel (Total SA)
In 2014, Total performed a surfactant-polymer single-well pilot to test the effectiveness of a surfactant formulation developed in-house, and including a new proprietary class of surfactants with improved temperature- and salinity-tolerance characteristics. This paper unveils the results of this pilot which targeted a high temperature, high salinity carbonate reservoir. The operations were performed on an oil bearing reservoir of Lower Cretaceous age, in an offshore field operated by Total since 1974 and located 180 km offshore Abu Dhabi. Dedicated topsides were designed and installed for this EOR project. Extensive in-house laboratory studies were performed to select and synthesize the chemicals. Specific simulations, using laboratory results as input, were carried out to predict the pilot performance, design the Single Well Tracer Tests (SWTTs), and size the equipment.
In this paper we will discuss the workflow used to select the most appropriate well and present the methods and results used to characterize the reservoir. Then we will relate it to the surfactant-polymer injection field operations. Finally the reservoir monitoring activities that were necessary to preserve reservoir integrity and demonstrate the pilot efficiency will be described.
The strong decrease in remaining oil saturation measured after the chemical EOR pilot clearly proves the effectiveness of the chemicals synthesized by Total to mobilize the remaining immobile oil after water-flood.
These positive outcomes change the perception of CEOR in hot, saline Middle-East carbonate reservoirs, and could be a "game changer".