Gas Generation and its Benefits in the Grosmont Reservoir during Thermal Recovery Process

ABSTRACT

The Saleski steam injection Pilot in Alberta, Canada, has proven recovery from a naturally fractured bitumen reservoir in the Grosmont carbonate. Non-condensable gases (NCG) generation and their behavior and flow in the reservoir have a significant effect on the performance of the thermal steam injection processes. This becomes even more important in a carbonate fractured reservoir where gas saturation and distribution largely impact Gas Oil Gravity Drainage (GOGD) process. Therefore, NCGs were likely instrumental in the successful recovery observed in the Grosmont Pilot. Understanding the role played by NCGs in the Cyclic SAGD process at Saleski can lead to insights and improvement in the recovery process.

The Saleski Pilot, a joint venture between Laricina Energy Ltd. and Osum Oil Sands Corp. started in 2010 to exploit the Grosmont carbonate fractured reservoir. Saleski pilot operation was ended in September 2015 as the goals of the project were achieved. During close to five years of operation of the pilot a great deal of data on all important parameters were collected. Gas production numbers as wells as gas composition were also measured and Laricina Energy Ltd. has agreed to make it available to the public. The NCG production data is reviewed for the whole period of operation and total GOR as well as individual gases GOR are calculated. This information is used to calibrate a kinetic reaction model which is implied in the numerical simulation work in order to examine the effect of NCG.

Results from lab experiment and Saleski Pilot show gas production higher than initial solution gas of the bitumen with substantially higher than expected concentration of CO₂. To further understand these observations, a kinetic model is developed and calibrated to the observations. This model was then implemented into reservoir numerical simulations to develop further insights into thermal bitumen recovery from the Grosmont and improve history matching practice of the Saleski pilot.

Gas generation, behavior, and flow inside the reservoir during a thermal steam process in a carbonate fractured reservoir have not been investigated previously. This work presents invaluable field data on gas production in Grosmont reservoir and further assesses the possible effect of NCG presence on recovery mechanisms.

A full version of this paper is available on OnePetro Online.