Shale Well Productivity: Quantifying and Minimizing Uncertainty in Decline Analysis
Dr. Frank Male
Bureau of Economic Geology
Because of the economic value of predicting production from gas and oil wells, there have been several decades of work in this area. The bulk of that work focused on vertical wells in high permeability reservoirs, but with the shale revolution, a new paradigm has taken its place, which requires rethinking the problem. Using the geometry inherent in a reservoir penetrated by a horizontal well with extensive hydrofractures, Patzek, et al (2013, PNAS) developed a physics-based scaling approach to describe production. The most important feature in the approach is that a well's production can be described by two parameters, the time to boundary dominated flow and the mass of fluid accessed by the well during production. Knowing just these two parameters leads to a complete understanding of the production potential for a well.
For wells that have entered boundary dominated flow, the two parameters can be determined with great accuracy. However, wells that are still in transient flow cannot have the parameters determined from first principles with any certainty. The focus of this talk will be determining and reducing uncertainty in these parameters for young wells using several statistical and physics-based techniques.