Changing a Low Potential Viscous Oil Sandstone Reservoir to the Biggest Conventional Incremental Project in the Neuquen Basin

Thompson, Anthony; Martino, Luis; Oviedo, Enrique; Sánchez, Fernando Roberto Chiapa; Barros, P.; Campos, Héctor S; Gandi, Silvana; Morettini, E.

doi:10.2118/177171-ms

Cited by 3 publications

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Alluvial fans and fluvial fans at the margins of continental sedimentary basins: geomorphic and sedimentological distinction for geo-energy exploration and development

Moscariello¹

2017

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Alluvial fans and fluvial fans are the most common depositional landforms along the margins of continental sedimentary basins. Their occurrence is determined by the area, relief and hydrology of the catchment, which ultimately control the relative ratios of sediment v. flow discharge and runoff regimes. Fundamental morphological and process distinctions exist between these two kinds of deposystem, which are seen as essentially different facies associations and internal architectures for the corresponding deposits. Alluvial fans commonly develop over short radial distances (hundreds of metres to a few kilometres) and are constructed by ephemeral, flash flow events that lead to poor organization of the sedimentary facies and overall architecture of the corresponding deposits. By contrast, fluvial (mega)fans are fed by proper river systems, which aggrade much larger volumes of clastic sediment over distances of up to a few hundred kilometres. Distinct channel belt and overbank domains are developed with a marked heterogeneity in the distribution of sedimentary facies, represented by hierarchically well-organized fluvial deposits. The general properties of alluvial and fluvial fans reflect the different potentials for the corresponding successions to host economically attractive oil and gas resources and the different approaches required in exploration and prediction.

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Alluvial fans and fluvial fans at the margins of continental sedimentary basins: geomorphic and sedimentological distinction for geo-energy exploration and development

Moscariello¹

2017

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Surveillance and Initial Results of an Existing Polymer Flood: A Case History From The Rayoso Formation

Martino¹,

Righi²,

Gandi³

et al. 2017

SPE Latin America and Caribbean Petroleum Engineering Conference

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A semi-regional 3D model of the Rayoso Formation in the Neuquén basin, Argentina, has been used to predict that several millions of barrels of additional oil can be recovered by polymer flooding in six fields of YPF S.A. As a result of static and dynamic modelling, two polymer flood pilots in separate fields have been approved. The first pilot started polymer injection in July 2016, while the second one is expected to commence in late 2017. This paper describes the approaches currently used and proposed for surveillance to ensure that the pilot objectives are met and to demonstrate the feasibility of field-scale application of polymer flooding across the Rayoso formation. A multidisciplinary integrated surveillance plan has been implemented to prevent the pilot from failing due to avoidable causes. Data on polymer quality monitoring, tracer surveys, interwell tracers, fall-off tests, and production and injection review are regularly fed into simulation models. We describe how this is achieved while limiting additional staffing and equipment costs. The pilot test discussed here lies in a multi-reservoir field where oil production is commingled with two deeper reservoirs. In order to make the oil production response to polymer injection directly detectable, the central producing wells in the pilot were recompleted to produce only from the Rayoso formation. Since there was no practical possibility to do the same for the second-line (offset) production wells, geochemistry techniques were used to identify the oil produced from each formation and thus estimate incremental produced outside of the pilot area. Although the Rayoso formation has been exploited for more than 30 years, only recently has it been given priority as a production target. At the beginning of the study, several major uncertainties exisited that could adveesely affect the potential success of polymer flooding in this reservoir, especially those regarding the initial and remaining oil saturation in the formation. As a result of the appraisal and surveillance plan applied, key project uncertainties were addressed or assessed by monitoring potential deviations of a set of variables from the project prognosis in real time. Interwell tracers and pressure fall off tests during the baseline waterflood provided data to reduce the uncertainty in the presence of possible flow barriers in the pilot area. Frequent production tests and continuous well bottomhole pressure data enabled calibration of the simulation model and to predict the behavior of the declining phase of the baseline waterflood with resasonable confidence. A single well polymer injectivity test with back flow, performed in one of the pilot injectors, showed that the selected polymer at the target concentration was not significantly degraded in the reservoir.

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Design, History Matching and Utility of a Simulation Model for a Polymer Pilot

Thompson¹,

Martino²,

Gandi³

et al. 2018

SPE Improved Oil Recovery Conference

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A polymer injection pilot started in 2015 in the Rayoso Formation, Desfiladero Bayo field (Neuquen Basin, Argentina) A detailed monitoring of the pilot was planned and the amount of data anticipated led to the construction of a reservoir model with a high level of detail in order to compare the results to prognosis and to reduce the uncertainty to the business case forecast. A specific complication was that the Rayoso Fm. had been produced to date in a commingled way with no exclusive production data before the pilot. Subsequently other data was needed to constrain the simulation model. Clearly, when the pilot started, the Rayoso Fm. was not in a virgin state (after ten years of waterflooding), so RFT data, saturation logs of infill wells, injection logs, tracer and geochemical data were used instead, adding production and injection exclusively from the Rayoso Fm. in the new wells and workovers subsequent to the pilot starting. The history match of the water injection stage of the pilot showed things that were not initially obvious; one was that the production of one of the pilot producer wells was not consistent with the log response and core data. It was subsequently established that errors were occurring in the production tests of this well in the field that were then corrected. Breakthrough times for water were consequently history matched and it was established that even after polymer injection started, water cut was expected to initially rise, this being key for expectation management. As the pilot has progressed, the tracer dosed with the polymer was seen before polymer, this suggesting either the presence of a thief zone or as a methodology for estimating the polymer retention. Additionally the mismatch of tracers between the simulation and actual data was used to estimate the real injection rates into the Rayoso Fm. of commingled injectors lying near the pilot area. In this paper we discuss how a detailed pilot simulation model can be constructed and constrained when production data specific to the formation is absent. Subsequently, when field results are different to expectation, simulation can be used as tool to establish the probable cause of the deviation from prognosis and hence identify remedial action if required. Finally, the simulation model was key to manage expectations; unrealistic expectations are one of the leading causes of pilots failing.

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Changing a Low Potential Viscous Oil Sandstone Reservoir to the Biggest Conventional Incremental Project in the Neuquen Basin

Cited by 3 publications

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Alluvial fans and fluvial fans at the margins of continental sedimentary basins: geomorphic and sedimentological distinction for geo-energy exploration and development

Alluvial fans and fluvial fans at the margins of continental sedimentary basins: geomorphic and sedimentological distinction for geo-energy exploration and development

Surveillance and Initial Results of an Existing Polymer Flood: A Case History From The Rayoso Formation

Design, History Matching and Utility of a Simulation Model for a Polymer Pilot

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