L. A. Kovaleva

Numerical simulation of injection of a solvent into a production well under electromagnetic action

The results of a theoretical investigation of the possibility of using powerful radio-frequency (RF) electromagnetic (EM) radiation combined with solvent injection in high-viscosity oil fields for the purpose of intensifying oil recovery are given. A mathematical model of the three-stage stimulation of a high-viscosity oil pool is proposed. The model takes into account the cross-flow heat and mass transfer effects initiated by the movement of a multicomponent system through a porous medium under the action of an EM field. A comparative analysis of the results of calculations of the proposed combined method and its components (EM treatment of the reservoir bottomhole zone without solvent injection and “cold” displacement of oil by a solvent) is carried out.

An investigation of the processes of heat and mass transfer in a multilayer medium under conditions of injection of a miscible agent with simultaneous electromagnetic stimulation

A numerical investigation is performed of the impact of high-frequency (HF) electromagnetic (EM) field on the process of filtering of miscible fluids and propagation of heat in a uniform stratum. The cross effects of heat and mass transfer, which arise under conditions of nonisothermal motion of a multicomponent medium in porous medium, are taken into account during simulation.

Simulation of high-viscosity oil production using electromagnetic radiation combined with hydraulic fracturing of formation

This paper presents the results of a study of the filtration and temperature fields in the inflow to a well with two perpendicular fractures induced by hydraulic fracturing under high-frequency electromagnetic treatment. The technology of a stepwise thermal treatment on the producing formation is considered; the results obtained for different capacities of the electromagnetic waves and for “cold” withdrawal are compared, and the sensitivity of the results to the pressure difference between the well and the formation and to the parameters of induced fractures is examined.

Combining solvent injection, electromagnetic heating, and hydraulic fracturing for multistage heavy oil recovery

To model the combined multistage technologies of radio-frequency electromagnetic heating (RF-EM), solvent injection, and hydraulic fracturing, a mathematical model was developed. It was assumed that the well was previously hydraulically fractured and then the solvent was injected through it with simultaneous RF electromagnetic irradiation. The radiator of RF-EM waves was located at the bottom of the injection well. When the electromagnetic waves were irradiated into the reservoir, the temperature rises and the viscosity of the liquid decreases around the fractured well. While “cold” solvent was injected, it was heated at the bottom of the well so that the heat was transferred into the fracture and reservoir by convection. This leads to an increase of reservoir coverage by heating. The area of the thermal effect was determined by the length of fracture, duration of solvent injection, reduction in oil viscosity, increasing injectivity due to rising temperature, and solvent–heavy oil mixing around the bottomhole. Multistage process of reservoir stimulation was considered: (1) «Cold» production of heavy oil through the fractured well, (2) shut (shutdown) of the well without treatment, (3) solvent injection into the fractured production well with simultaneous RF-EM heating, (4) well was suspended to “soak” without any treatment, and (5) production of heavy oil with solvent without heating. The most efficient scenario was the combined RF-EM heating/fracturing multistage production technology. Recurring stages of solvent injection/RF-EM heating allowed maximum use of thermal energy and achieved the most efficient production growth.

Microstructure evolution of water-oil emulsions in high-frequency and microwave electromagnetic fields

We investigate the impact by high-frequency (HF) and microwave electromagnetic (EM) fields on the microstructure of oil-water emulsions. The laboratory stand for those studies is described. We present the investigation results showing the patterns of the evolution of the water-oil emulsions depending on the EM field parameters and the dielectric properties of the emulsions.

Heavy Oil and Bitumen Recovery Using Radiofrequency Electromagnetic Irradiation and Electrical Heating: Theoretical Analysis and Field Scale Observations

Heavy-oil and bitumen recovery from difficult geological media such as deep, heterogeneous and high shale content sands and carbonates, and oilshale reservoirs requires techniques other than conventional thermal and miscible injection methods. Materials in oil reservoirs (formation water, crude oil, oil-water emulsions, bitumen and their components like resins, asphaltenes, and paraffin) are non-magnetic dielectric materials with low electrical conductivity. If the electromagnetic field can be created to change these properties, electro-thermo controlled hydrodynamics could improve the displacement and recovery of heavyoil/bitumen. This paper deals with the recovery improvement of heavy-oil/bitumen by Radio-Frequency (RF) Electromagnetic (EM) radiation. The RF-EM fields in the form of waves can penetrate deeply enough from fractions of a meter to several hundred meters into oil and gas containing reservoirs to generate heat and eventually improve recovery mainly due to the reduction of oil viscosity. The recovery mechanisms and the dynamics of the RF-EM heating process were analyzed for several field scale applications in Russia. In the Yultimirovskaya tar sand deposits, RF-EM energy was transmitted from the RF-EM generator, located at the surface, into the formation by a coaxial system of the well pipes. Another field example analyzed was the RF-EM stimulation process in several wells of the Mordovo-Karmalskaya tar sands performed in the 1980s. It was observed that the formation was heated to the temperature which was sufficient for injection of oxidant (air) to initiate fire flooding. Then, a mathematical model of this process was presented with a sample exercise. Some data needed for this exercise were obtained from the field tests evaluated. Field tests proved the efficiency of the RF-EM stimulation of heavy oil / bitumen deposits with low water cut values (in operating production wells with water cut <30% on early field development stages). Numerical simulations suggest that bottomhole temperature and heat/mass transfer effects in the reservoir can be controlled by setting the output performance of the RF generator and by the difference between the reservoir and bottom-hole pressure. Introduction Applying radio-frequency electromagnetic energy (RF-EM) into heavy-oil reservoirs is an unconventional stimulation method. The RF-EM radiation generates a volume source of heat in the reservoir rock. Due to dielectric absorption in the medium, the EM energy transforms into thermal energy, and the resulting heat reduces the viscosity of the reservoir fluids. Results of RF-EM treatment experiments were well documented in numerous studies (Chakma and Jha, 1992; Kasevich et al., 1994; Nigmatulin et al., 2001; Ovalles et al., 2002). Theoretical aspects of heavy-oil production were covered by Abernethy (1976), Islam et al. (1991), Sahni et al. (2000), Sayakhov et al. (2002), and Carrizales et al. (2008). Several other studies investigated the heat and mass transfer processes in heavy oil reservoirs stimulated by EM radiation (Sayakhov et al., 1998; Kovaleva and Khaydar, 2004; Kovaleva et al., 2004; Davletbaev et al., 2008 and 2009). A number of other investigations proposed analytical models of lab experiments (Hiebert et al., 1986; Ovalles et al., 2002).

Acoustic wave energy absorption and distributed heat sources upon an acoustic impact on media

The absorption of acoustic wave energy by media and the occurrence, in that connection, of distributed heat sources are investigated. The distribution of the totality of heat sources for the case of impact on an oil bed by high frequency electromagnetic and acoustic fields is considered. Comparative graphic charts of distribution of the heat sources produced by these fields separately and in total are provided, and the results obtained are analyzed.

High-viscosity oil flow in a formation with a hydraulic fracture under the action of a high-frequency electromagnetic field

The results of numerical investigations of high-viscosity oil flow in a low-permeability reservoir under high-frequency electromagnetic action in combination with hydraulic fracturing are presented. The fluid flow toward a solitary vertical sand-filled fracture with high permeability, much higher than the permeability of the formation, is considered. The electrophysical and thermal characteristics of the formation and fracture both saturated with formation fluid are assumed to be identical. The unsteady fluid pressure, temperature and viscosity fields near the hydraulic fracture are calculated and the efficiencies of high-viscosity oil extraction are compared for different electromagnetic radiation powers and “cold” fluid withdrawal.

Experimental studies of heating rheologically complex fluids with electromagnetic field

Heating of rheologically complex fluids in electromagnetic field in a coaxial system is studied. The experimental results show that the dynamics of changes in temperature of the fluid are affected by the electromagnetic field.

Determination of temperature in an emulsion drop under microwave radiation

The effect of microwave radiation on an individual emulsion drop is studied. The laboratory bench for exploring the microwave radiation on an individual emulsion drop is described. The dynamics of the temperature change inside the micron drop under microwave radiation is studied.