The physical property data (densities, excess molar volumes, viscosities, surface tensions, and refractive indices) for ethanol + glycerol have been determined at 294 K and atmospheric pressure. Densities were determined by a vibrating-tube densitometer, viscosities were determined by U-tube viscometers, surface tensions were determined by the Du Noüy ring method, and refractive indices were determined by an Abbe refractometer. Excess molar volumes were computed from density values and were fit to the Redlich-Kister equation.

Dimethyl Ether Enhanced Waterflood (DEW) is a novel and promising solvent-based EOR technology developed by Shell. Dimethyl Ether (DME) is a widely-used industrial chemical which is applied as a water soluble solvent for EOR applications to enhance a conventional waterflood. Once the DME-brine solution is injected into the reservoir and comes in contact with the oil, the DME molecules partition into the oil phase which leads to oil swelling and mobilization of residual oil. Moreover the partitioning of the DME into the oil phase decreases the oil viscosity and improves its mobility. The combination of these effects results in both a significantly higher ultimate oil recovery compared to the conventional waterflood as well as accelerated oil production at lower energy footprint compared to thermal technologies. As the solvent is water soluble, it can be very effectively back-recovered from the reservoir by re-dissolving the trapped DME in the DME-free chase water slug. The solvent is recovered from the produced oil and water streams at surface and re-used. The main objectives of this paper are to present the first experimental results, explain the physical mechanisms of this novel concept and demonstrate the extra oil recovery. Additionally, modeling workflows used to interpret the experiments and predict the benefits of field EOR application are illustrated.To gain an insight into physical mechanisms behind the DEW, develop modeling workflows and de-risk the technology, an extensive experimental program was set up to investigate both the fluid-fluid and rock-fluid interactions. Phase behavior of DME/brine and DME/crude mixtures has been carried out, with a focus on the partitioning of the solvent between brine and crude. Mixing rules for properties affecting the phase mobilities have been determined. In parallel, a number of coreflood experiments were conducted on both carbonate and clastic cores of varying permeability to investigate the dynamic DME/crude behavior and DME/rock interaction. PVT experiments were used to build phase equilibrium models. Based on these PVT models, the coreflood experimental data was matched and interpreted using numerical simulation.Coreflood experiments confirmed the phase behavior-driven character of the DEW technology. A good match between the experimental and simulated oil recovery was obtained in most cases. This shows that PVT models, generated using measured basic data, are in a good agreement with the dynamic coreflood experiments.

A set of analog vapor-extraction (VAPEX) laboratory experiments was performed to test the ability of existing analytic and numerical models to predict oil-drainage rates from this process. The selected analog fluids and porous media enabled all input parameters to the analytic model to be determined independently of the analog VAPEX experiments without history matching. The results show that the underprediction of oil rate by the standard analytic model is not because of increased levels of mixing between the solvent and oil over that expected from molecular diffusion and convective dispersion, but rather because of a deficiency in the analytic model formulation.

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The availability of ~ 7 years of actual performance data for the ongoing field-scale polymer flood in South of the Sultanate of Oman provides ample opportunities to reveal the reservoir dynamics and its interplay with induced EOR mechanism. The paper focusses on analysis of the polymer pattern behaviour, underlying reasons for such response and key indicators to characterize pattern performance. Upsets in surface polymer injection facility leading to the phenomenon of WAP (Water-Alternating-Polymer) and it's impact on recovery is also assessed in context of actual field examples. The paper then illustrates how this information could be exploited to counter challenges faced in the field, enhance polymer pattern performance, optimize it's further expansion and de-risk any other future EOR development. A nested modelling approach has been employed, wherein models at different scales are generated, tailored to meet the objectives. High resolution 3D conceptual models are built in Shell proprietary tool PolyMoReS to calibrate the model response against the actual polymer pattern behaviour in the field, study the impact of mixing between polymer and water slugs in WAP type of recovery, and affirm the correct polymer rheology. Three segment models covering the field are created and history matched with the use of Stochastic Uncertainty Management. Attempts have been made to obtain history match (HM) on segment, pattern and well levels, with greater emphasis on polymer patterns capturing polymer oil response, water-cut reversals and polymer breakthroughs. Models are then complemented by Pressure Fall-Offs, tracer tests and PLTs to capture uncertainties in fracture growth and areal and vertical conformance. The HM model is then used to predict polymer performance. Significant insights into waterflood and polymer flood performance are gained, which help improve the pattern performances. Assessment of WAP with both conceptual Physics and field segment models demonstrate considerable deferment of oil. Capturing injector – producer connectivity has proven the most pivotal element in explaining polymer oil response and breakthrough. Models indicate that lower than expected incremental recovery and sharper decline of oil response in some patterns are related to the lower polymer mass injected, which in-turn could be attributed to many operational factors (e.g., polymer injection uptime, injection rate, low injection viscosity, WAP), and the presence of natural fractures or uncontrolled growth of induced fractures. The study also reveals optimization opportunity to reduce the volumes of back produced water. The paper presents a comprehensive multi-scale reservoir modelling study for a field with significant historical data of large scale polymer flood. Impact of WAP injection, reflecting the reality of interruptions in polymer flood due to operational upsets, on medium to long term polymer flood value is presented. Analysis of polymer patterns in the field demonstrates how different key indicators e.g., PUF (Polymer Utilization Factor) can characterize pattern performance throughout its life-cycle and answers questions, e.g., why some patterns behaved well, while others not.