# Electromagnetic radiation in heavy oil recovery process. Assessing a numerical model to predict the oil mobility

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## Abstract

New recovery technologies are having an impact on heavy oil production which makes many marginal projects profitable. Before applying any technology or investing any capital in that, it is very important to have a model that can predict the results or oil recovery ratios. This paper deals with a model for predicting the flow in porous media of heavy oil using one of these emerging technologies (electromagnetic field) for heavy oil recovery. Some experiments were performed using different scenarios and thus evaluate the accuracy of the model developed in this article. It was found that the time and the frequency of the waves are key factors in promoting oil production. Also the article presents preliminary results of the model which will be useful for selecting the optimal frequency and time to stimulate heavy oil production to industrial scale.

## Keywords

Heavy oil Model Oil recovery Electromagnetic waves Simulation## Introduction

- a.
Reduction in the use of chemicals such as acids and solvents.

- b.
More precise stimulation of the wellbore can be accomplished as it can be directed to any defined interval.

- c.
It can be carried out during production of the well.

Recovery rates are determined by the mobility of the crude within a formation (Kovaleva et al. 2011). While artificial and enhanced oil recovery techniques may help in this matter, it is important to test and simulate the process before a decision on enhanced recovery can be recommended. A model for interfacial area dynamics based on pore scale is necessary for the simulation of the multiphase porous media.

In the literature, some references can be found, however few of them display a model that can be used for predicting the behavior of the technique before it can be implemented (Hascakir et al. 2008; Kovaleva et al. 2011; Sahimi 1995; Haque 1999). The phenomenon is based on molecular structures of the oil and porosity of the soil basically. Oils in different deposits vary in chemical properties and characteristics of the soil. The estimation of the size of the pore channel is a crucial factor for estimating the production of oil and permeability (Kovaleva et al. 2011; Masliyah et al. 2008). The objective of this article is to create a model for predicting the dynamic conditions and production of the well under electromagnetic radiation. This model can allow the user to estimate the effects of the method on oil production and it can be used in field-scale reservoirs.

## Experimental setup and model

*V*is the volume of the pore body,

*V*

_{s}is the local saturation,

*N*is the number of the pore in the body (31 % approximately), and

*Q*the volumetric flow from pore

*i*to pore

*j*. In order to calculate the volume average in saturation, a representative volume should be defined where the volumetric flow is related to pressures using Poiseuille´s law

*P*the pressure. Boundary pressure is fixed to 300 kPa. In all simulations, we assume that the contact angle is zero and the radii of the pore bodies and pore throats are generated using a cut-off log normal distribution using upper and lower radius values shown. Finally the volume average velocity is given by the sum of each interfacial velocity weighted by area of interface.

*a*is the interfacial area per volume and

*A*is the total interfacial area (Davletbaev et al. 2011). By capillary theory, the radius can be estimated according to

*p*is pressure and

*σ*is the surface tension. The energy balance is not included because the system was set up at a constant temperature. Assuming symmetry in radial homogeneous conducting medium (Bientinesi et al. 2013; Santos et al. 2011). The radial pressure distribution will be calculated as follows

*γ*is the power absorption and depends on the type of material and

*φ*is the power per unit area (W/mm

^{2})

*T*can assume constant at 5 °C maximum. This Eq. (6) allows us to predict the density according to the electromagnetic radiation applied to the system. The efficiency of the electromagnetic field at experimental scale does not depend on the polar components of the oil.

Influence of the gravity at 50 cm and 250 MHz

Gravity (API) | Velocity (mm/s) (average) | Velocity (mm/s) (model) |
---|---|---|

8 | 26 | 27.1 |

9 | 30 | 31.3 |

10 | 36 | 36.1 |

Influence of the gravity at 50 cm and 100 MHz

Gravity (API) | Velocity (mm/s) (average) | Velocity (mm/s) (model) |
---|---|---|

8 | 27 | 27.1 |

9 | 29 | 30.4 |

10 | 36 | 35.6 |

Influence of the height at 9 API and 250 MHz

Height (cm) | Velocity (mm/s) (average) | Velocity (mm/s) (model) |
---|---|---|

25 | 25 | 26.1 |

35 | 31 | 30.4 |

50 | 36 | 36.3 |

60 | 44 | 44.1 |

80 | 54 | 34.1 |

Influence of the time of application of the EM at 250 MHz

Time (h) | Velocity (mm/s) (average) | Velocity (mm/s) (model) |
---|---|---|

Oil sands at 8 API and 50 cm height | ||

0 | 20 | 20.2 |

8 | 35 | 37.2 |

15 | 48 | 47.2 |

25 | 56 | 55.5 |

Oil sands at 9 API and 50 cm height | ||

0 | 20 | 20.2 |

8 | 31 | 29.3 |

15 | 46 | 47.8 |

25 | 54 | 54.8 |

Oil sands at 10 API and 50 cm height | ||

0 | 20 | 20.2 |

8 | 29 | 32.1 |

15 | 42 | 41.7 |

25 | 51 | 51.5 |

Influence of the frequency at 50 cm and 9 API

Frequency (MHz) | Velocity (m/s) (average) | Velocity (mm/s) (model) |
---|---|---|

80 | 34 | 34.2 |

150 | 46 | 45.3 |

250 | 54 | 54.1 |

To assess the effect of the height in the production, the results are shown in the Table 3. The results also reveal that the increase in the oil production was more pronounced at large height because it contains more oil.

All results were analyzed (included or not in this article), we found that the three key requirements in this method are: the exposed time to the wave, the frequency, and the gravity (API). These requirements allow to increase the production in the well significantly. Among different schemes it was observed that this technique never lets the well fall below the base oil production. This finding suggests that any wave frequency and or short-time application stimulates the oil production.

## Conclusion

Overall, we believe that the model captures many of the essential features of flowing heavy oil and the effect of the electromagnetic field on the sands. The different variations of time and frequency should be considered depending on the reservoir and fluid properties. The results showed in this article were obtained to small scale, thus electrical conductivity should increase with increasing water saturation in big fields. We are currently working this model to real scale. We expect to continue to use the same framework presented herein to calculate the average velocity nevertheless, the electromagnetic field generator used at industrial scale is different from the generator used in the laboratory. Microwave energy was depicted to be effective in some applications; however, it is not used commercially at the present time.

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## Copyright information

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