Using Decline Curve Analysis to Forecast Production in Unconventional Reservoirs

The application of "Decline Curve Analysis" (DCA) in unconventional reservoirs may be problematic.  The Arps relations (hyperbolic and exponential relations) have been the standard for evaluating estimated ultimate recovery (EUR) in petroleum engineering applications for more than 80 years.  However, with the pursuit of low and ultra-low permeability plays, these relations often yield ambiguous results due to invalid assumptions (e.g., existence of the boundary-dominated flow regime, presumption of a constant bottom hole pressure, etc.). Misapplications of the Arps' relations to production data exhibiting long-term, transient flow will generally result in inaccurate estimates of reserves. In a paper published by the Society of Petroleum Engineers, D&M experts present guidelines for the application of the various rate-time relations currently being deployed in the petroleum industry, with examples from three different shale plays. They lay out the advantages/disadvantages of each decline curve relation in the paper.  For more information on D&M’s expertise in evaluating unconventional reservoirs, send an email to its Dallas office.