Page 151 - Fundamentals of Enhanced Oil and Gas Recovery

CHAPTER FIVE

Thermal Recovery Processes

1
1
Forough Ameli , Ali Alashkar and Abdolhossein Hemmati-Sarapardeh 2
1
School of Chemical Engineering, Iran University of Science and Technology, Tehran, Iran
2
Department of Petroleum Engineering, Shahid Bahonar University of Kerman, Kerman, Iran

5.1 INTRODUCTION

The recovery processes of oil are increased due to dependency of the industry
to them and the requirements to petrochemical products. This leads to oil extraction
from unconventional reservoirs to compensate the possible deficiency between pro-
duction and demand, and oil with low API gravity. The total amount of heavy oils
and bitumen is about 9 trillion barrels. The characteristics of these oils include low
API gravity, high viscosity, and asphaltene content [1]. One technique for increasing
the displacement which leads to enhancement of heavy oil recovery is viscosity reduc-
tion [2]. The fluid resistance to flow is called viscosity. Reduction of this quantity
leads to increasing the mobility value as temperature is increased [3]. This fact states
the significance of enhanced oil recovery (EOR) (thermal EOR) processes, in which
the generated heat at the surface or in situ from steam or hot water is injected
through the porous media [4].

5.2 VARIOUS THERMAL ENHANCED OIL RECOVERY PROCESSES

Various methods of thermal EOR are applied in different ranges of viscosity.
For example, steam flooding is effective for heavy oil extraction, cyclic steam stimula-
tion (CSS) is applicable for extra-heavy oil, and steam-assisted gravity drainage
(SAGD) process is introduced for the recovery of bitumen [5]. This process leads to
generation of greenhouse gases as a result of burning the fuel which may cause envi-
ronmental problems. Solvent steam process was then introduced to resolve this envi-
ronmental issue by generating less amount of steam. This leads to reduction in
amount of emitted greenhouse gases [6,7]. If solvents for instance normal alkanes,
CO 2 , and CH 4 are also added to this stream, viscosity reduction would be increased

Fundamentals of Enhanced Oil and Gas Recovery from Conventional and Unconventional Reservoirs. © 2018 Elsevier Inc.
DOI: https://doi.org/10.1016/B978-0-12-813027-8.00005-9 All rights reserved. 139