A Novel Enhanced Oil Recovery Technique: Experimental Results and Modelling Workflow of the DME Enhanced Waterflood Technology

Abstract

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.

Compositional modeling and simulation of dimethyl ether (DME)-enhanced waterflood to investigate oil mobility improvement

“…Recently, dimethyl ether (DME) was investigated as a potential solvent for EOR. DME, a well-known industrial chemical used as a fuel additive and aerosol propellant, has recently been used as a replacement for transport, cooking, and heating fuels (DME Handbook 2007; Chernetsky et al 2015). In recent years, DME has been considered as a solvent for EOR.…”

“…In recent years, DME has been considered as a solvent for EOR. In particular, Shell has studied and developed this process (Chernetsky et al 2015;Groot et al 2016;Parsons et al 2016). DME is often compared to LPG due to their similar physical properties; however, the solubility of DME in water is almost 1000-fold greater than that of propane (Parsons et al 2016).…”

Field-Scale Modelling and Sensitivity Analysis of DME Enhanced Waterflooding

“…Fundamentally, this phase behaviour driven EOR process is based on an immiscible displacement of the oil phase by the water phase, enhanced by DME mass transfer between the two phases. Modelling such a process is far from trivial and requires a tailored modelling approach.In previous work (Chernetsky, et al, 2015) a dynamic model for DEW was successfully employed to history match core-flood experiments. This paper builds on this work by analyzing the driving mechanisms and sensitivities at different stages of the DEW process and describing the process of efficient upscaling of the model to field scale.…”

“…In previous work (Chernetsky, et al, 2015) a dynamic model for DEW was successfully employed to history match core-flood experiments. This paper builds on this work by analyzing the driving mechanisms and sensitivities at different stages of the DEW process and describing the process of efficient upscaling of the model to field scale.…”

“…Introduction DME Enhanced Waterflood (DEW) is a novel EOR solution that has the potential to significantly increase oil recovery from both mature and new waterflood developments (Chernetsky, et al, 2015). The active agent in this EOR process is DME, which is dissolved in water and injected in the reservoir.…”