Field-Scale Modelling and Sensitivity Analysis of DME Enhanced Waterflooding

Abstract

Di-methyl-ether (DME) is a solvent with clear potential for EOR through its novel use in DME enhanced water flooding (DEW). 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.The first part of this paper presents the basic modelling workflow for DEW for light to medium oils and typical concentration and saturation profiles and ternary diagrams. The objective is to determine the main driving mechanisms and their impact on the incremental oil recovery and DME utilization. The second part of the paper focusses on the upscaling of the DEW model to field scale. In particular, sensitivities to reservoir heterogeneity, relative permeability data and grid size are discussed through examples of sector and field models.The one-dimensional sensitivity studies provide valuable insight into the efficiency and dependencies of the fundamental recovery mechanism. The sensitivities focus on incremental oil recovery and DME efficiency and cover design parameters relevant to the DEW process, such as DME slug size and brine salinity, oil properties, remaining oil saturation and parameters used in simulation studies, such as grid size.Results for field scale modelling give guidance on how the DEW models can be effectively upscaled and what sensitivities can be expected at reservoir scale, and show the value of the model in supporting decision making and implementation of DEW in the field. Recommendations for field scale modelling are given, based on sensitivity analyses for various DEW scenarios. Computational techniques, such as adaptive gridding and parallel computing, are proposed to overcome limitations due to grid size sensitivity.

On Oil Recovery Mechanisms and Potential of DME–Brine Injection in the North Sea Chalk Oil Reservoirs

“…Chahardowli et al also studied the impact of DME on spontaneous imbibition of oil in carbonate and sandstone cores. Groot et al carried out reservoir scale simulations for the DME EOR technology and studied the sensitivity of the results to different design parameters. Te Riele et al investigated the importance of reservoir management and designing suitable well patterns in the field implementation of this technology.…”

Numerical modeling of water-soluble solvents for enhancing oil recovery in heterogeneous chalk reservoirs

“…R. Ratnakar et al, 2016;Ratnakar et al, 2017aRatnakar et al, , 2017b or DEW core scale modeling (M. Groot et al, 2016a). Moreover, in all of the previous publications, the swelling and viscosity reduction of oil are suggested as the main mechanisms of DEW enhanced oil recovery, which seems inadequate given the small difference between the liquid density of DME and oil (Groot et al, 2016c), and large extent of extra oil recovery by DEW, which seems to be more than the limited equilibrium swelling. This is one of the aspects that will be discussed in this paper.…”

“…DME is a colorless gas at standard condition but it liquefies at low temperature or high pressure (Fujimoto et al, 2007). It can be manufactured from methane, which is supplied by natural gas or gasification of coal (Groot et al, 2016b). DME is miscible with oil and due to its slight polarity, it also can be dissolved in water, which makes it an attractive candidate for tertiary recovery as an additive to the injected water.…”

“…The recovered DME can be used for reinjection or injection in neighboring wells. The efficiency of DME recovery depends on the heterogeneity and well completion (Groot et al, 2016b). Through a series of core flooding tests, Chernetsky et al (2015) showed that most of the injected DME could be recovered from the core by only one pore volume injection of chase water.…”

Dimethyl Ether Enhanced Oil Recovery in Fractured Reservoirs and Aspects of Phase Behavior

“…A recently proposed solvent for the mutually soluble solvent-based EOR technique is dimethyl ether (DME). DME, the simplest ether, is a colorless gas at atmospheric conditions, which liquifies at moderate pressures and ambient temperature. − It is a nontoxic compound, environmentally benign, , and partially soluble in water, which then exhibits first-contact miscibility with the oleic phase. The combination of these favorable properties has recently attracted the attention of the oil industry.…”