A Mechanism of Gas Production in SAGD

Abstract

The dissolution of gas in both water and bitumen as a mechanism contributing to gas production in SAGD is studied. The contribution of this mechanism to the production of gas in SAGD is evaluated through the implementation of appropriate thermodynamic models into a series of numerical simulations in order to more accurately represent the physics of gas behavior inside the SAGD chamber. Methane, carbon dioxide and hydrogen sulphide are considered. It is observed from the numerical simulation results that the production of a gas in SAGD is directly proportional to the solubility of that gas in the liquid phases being produced. Additionally, these results lead to the conclusion that gas dissolution is an important mechanism in gas production. Results from this study also confirm the findings observed by other researchers that gas will accumulate at the front and top of the SAGD chamber, thus reducing SOR and oil production rates. The degree of such accumulation of gas depends, among other operational and reservoir conditions, on the solubility of that gas in the liquid phases under the temperature and pressure conditions inside the steam chamber.

A Critical Review of Reservoir Simulation Applications in Key Thermal Recovery Processes: Lessons, Opportunities, and Challenges

“…Heron et al (2008) proposed a set of K -values in a simulation study to model NCG solubility in both water and bitumen, which would help gas removal from a steam chamber during production . Canas and Kantzas in 2012 also thought that more gas should be produced due to its relative high solubility in water during coinjection . Nourozieh et al in 2015 proposed a concept of rate-dependent dissolution and ex-solution of solution gas to model NCG coinjection, which showed an improved oil rate and reduced SOR .…”

“…234 Canas and Kantzas in 2012 also thought that more gas should be produced due to its relative high solubility in water during coinjection. 235 Nourozieh et al in 2015 proposed a concept of rate-dependent dissolution and ex-solution of solution gas to model NCG coinjection, which showed an improved oil rate and reduced SOR. 236 Mendoza and Kantzas in 2020 stated a new gas−liquid relative permeability for a steam and NCG coinjection process based on laboratory measurements.…”

3D experimental investigation on enhanced oil recovery by flue gas assisted steam assisted gravity drainage

“…However, this technique also has some defects, including that high consumption of steam, serious heat loss, and incomplete steam chamber development, which restricts the oil recovery factor (Lawal, 2014;Li et al, 2013;Shin and Polikar, 2006). To solve the above problems, non-condensable gas such as flue gas and natural gas was proposed to inject into the production of SAGD (Butler, 1999;Butler et al, 1999;Butler et al, 2001), an abundance of subsequent experiments and simulations confirm that it could effectively reduce the heat loss of the top of the reservoir (Canas and Kantzas, 2012;Lin et al, 2012) by forming a heat insulation layer, expand the sweep range of the steam chamber (Fatemi,2010;Yuan et al, 2018), slow down the topwater drainage, contributing for improving the oil-steam ratio and the production of SAGD (Jiang et al, 2000;Li et al, 2011Li et al, , 2017Pang et al, 2017). In addition, by taking advantage of gas lifting, non-condensate gas, such as natural gas and carbon dioxide, can be injected into reservoir through the tubing, which can reduce crude oil density and bottomhole pressure, the fluidity of crude oil is enhanced and well production is increased.…”

Numerical simulation of solvent and water assisted electrical heating of oil sands including aquathermolysis and thermal cracking reactions

“…Gas generation from oil sands is often modeled using a solubility concept . In this approach the aquathermolysis reactions are not included and instead CO 2 and H 2 S were sourced in formation water and bitumen and exsolved throughout the thermal recovery process . In these studies, the importance of gas generation on performance of SAGD was highlighted and it was found that inclusion of gas generation slowed the recovery process …”