On fingering of steam chambers in steam‐assisted heavy oil recovery

Abstract

Western Canadian oil sands reservoirs are among the largest petroleum accumulations in the world. Given original oil viscosity up to 5,000,000 mPa‐s, these oils are currently recovered from these reservoirs using steam which heats the oil to ∼250°C with reduced viscosities <10 mPa‐s. A key issue faced by thermal recovery processes is the uniformity of the steam chamber within the reservoir. Nonuniformities of the chamber arise from multiphase flow instabilities in the porous media where fingering has been explained by penetration of low viscosity steam into viscous oil. Here, fine‐grid thermal reservoir simulation reveals that fingering takes place in the gas phase beyond the chamber edge in a zone created by gas exsolution due to elevated temperature beyond the edge of the steam chamber. The results suggest that nonuniform chambers will occur in perfectly homogeneous reservoirs which implies that uniform chambers along wells may be impossible to achieve. © 2015 American Institute of Chemical Engineers AIChE J, 62: 1364–1381, 2016

Thermal Viscous Fingering in Thermal Recovery Processes

“…Analytical studies by Gotawala and Gates [7] also estimated the height of steam fingers to be of order of millimeters to tens of centimeters. Whereas it was originally believed that the linear instability that arises at the steam interface will result in non-uniform heating of the bitumen leading to poor sweep efficiency, Zhu et al [8] show that linear instability at the steam-oil interface is induced by ex-solution of solution gas from bitumen. They also show that fingers could be beneficial to the heat transfer process as it increases the contact area for heating.…”

“…Fingering occurs and creates instability in the steam-oil interface since lower viscosity steam channels through HO/B due to unfavorable mobility ratio. It is believed that this enhances the heat transfer area resulting to additional heat transferred to the bitumen reservoir [8]. The thrust of the research described here provides further insights on heat transfer and fluid flow dynamics beyond the steam-oil interface.…”

A fishtail well design for cyclic steam injection—A case study from Yarega heavy oil field in Russia

“…Furthermore, wellbore hydraulics is also postulated as a reason for this preferential flow of steam into fractures. Factors affecting the wellbore such as irregular steam pressures during injection, formation damage, and multiple steam injection points at uniform locations could have impacted the fixed upward distribution of steam in the domain . The improved contact points by the fishtail wells, as well as the cyclic injection strategy, meant better steam conformance was achieved and a more sustained recovery was derived from the reservoir.…”

“…With the use of the commercial package CMG‐STARS 2017, we obtain solutions to the final set of matrix equations using Newton‐Raphson iterations. CMG‐STARS has been used in the modeling of heavy oil‐related problems for several years with great accuracy . A high‐performance computing cluster (HPCC) system was used to run the simulations for computational speeds.…”

Instability of parallel flow of two immiscible liquids in a pore and application to steam‐assisted gravity drainage

“…At more than 200 C, the viscosity drops to less than 10 mPa s and it can be drained from the reservoir. [13] In these processes, injected steam loses its latent heat to the oil sand, raising the temperature of the oil with consequent formation of steam condensate. With greater mixing at the interface between mobilized (heated) oil and steam condensate, if instabilities occur, there is an opportunity for mixing with resulting enhanced heat transfer and emulsion formation.…”