Exploitation of unconventional resources is evolving rapidly. Case in point: liquid-rich shale (LRS) plays, once impermeable source rock, are now a prime target for unconventional exploration and development, with economic plays, such as the Eagle Ford, proving the potential. However, given complex and expensive completion, drilling and production operations combined with relatively low production rates and commodity prices, slim economic margins will likely prevail for the foreseeable future. Hence, the difference between economic success and failure could be the pace at which an economically robust development plan can be conceived, tested and implemented.
With this in mind, entry into new plays must rapidly and intelligently build on all unconventional best practices to-date – of which there is no shortage. Unfortunately, most are presented as rules-of-thumb, intuitive-but-unquantifiable or come with a long caveat list. Thus, the authors of this paper chose to quantify the credible ranges of several selected best practices based on the belief that there are only a handful of key engineering and geological levers that have step-change influence on production and cost (as opposed to optimizations). We have built an unconventional development workflow that identifies them, quantifies them, risks them and constructs full field development scenarios, which are economically evaluated and ranked, using only initial exploration data. Thus, even early appraisal wells can be planned to mitigate development risks and ensure the highest value geological and engineering data is collected early and used to steer timely development decisions.
The workflow is not novel, but at its core it accepts the inherent uncertainty of unconventional reservoirs and seeks to test end-member cases to drive decision making. This workflow was applied by Shell while planning the development of the Duvernay LRS play in Canada and will be described in that context. It consists of:
Identifying the key, play specific development levers
Gathering and analyzing analogue play data on these levers
Constructing individual well production profiles and economics
Building field development "end game" scenarios
Evaluating full development economics to understand total project value and robustness