In Steam Assisted Gravity Drainage (SAGD) operations, steam is the primary means of mobilizing the in-situ bitumen or heavy oil-Bitumen (HO-B) resource. The cost of steam generation and delivery accounts for a significant portion of ongoing operational expenditures of the recovery process, thus any efficiency gains in delivering steam to the reservoir makes the entire process more cost effective. Two significant challenges that impact the process efficiency are the occurrence of steam breakthrough along the lateral and steam non-conformance. Both of these issues are largely due to the presence of reservoir heterogeneities. A possible solution to address these challenges is the inclusion of flow control devices (FCDs) in SAGD completions.
In order to quantify the impact of including FCDs in the SAGD process, this study was performed by numerical analysis with a model built from publicly available geological data representing the Surmount field of Alberta. The model has the reservoir fully coupled to a discretized wellbore. With this model, the study is able to capture the presence of heterogeneities and the effect with respect to steam breakthroughs and non-conformance. Several wellbore variations are tested in this study, including a Base Case having a traditional completion (long string/short string completion) and other cases with various FCD configurations and arrangements.
The results of the modeling process show that the inclusion of FCDs positively impacts the SAGD process by minimizing the occurrences of breakthroughs, improving conformance and by increasing the volumetric sweep efficiency of the process. Included is a comparison of the results from the Base Case versus other cases. The comparison presents a conclusion which demonstrates that deploying FCDs in SAGD wells provides an economic benefit. The economic comparison is based on net present value (NPV) analysis and payout of the various cases. This study is relevant because it demonstrates how FCDs can be employed to overcome geological challenges that would otherwise result in non-conformance and steam breakthrough. By overcoming these challenges the project economics improve. The functionality of these devices also presents the possibility of using slimmer and longer completions for the SAGD well pairs which will improve project economics even more.