Best Practices for New Well Fracs and Legacy Well Refracs Course
IES started teaching a refrac course in 2008 following the natural gas price dip that year, focusing primarily on conventional tight gas reservoirs. Motivation was the result of working on dozens of integrated reservoir characterization projects that showed huge volumes of stranded reserves. When the petrophysical analyses were integrated with geology and reservoir engineering it was observed in virtually every field study that there were significant volumes of stranded oil and gas. When the completion information was introduced, it appeared that completion engineers assumed that fracs were “reserve seeking missiles” and would find the pay. More often than not the fracs found the depleted areas of the reservoir. The result was numerous gas fields with +/- 10% recovery factors (vs 65% to 75%) and oil reservoirs with single digit recoveries vs 14% to 15%. IES published the first of many refac papers in 2009 (SPE 125008), the emphasis was on evaluating the original hydrocarbons in place and determining if there were remaining reserves that could be economically recovered. It focused on wells that did not use “best practices” in the original completion using the findings from SPE 90483 (Barba and Shook 2004). The paper recommended using expandable liners for mechanical isolation in all cases and recommended against bullheads. The industry eventually recognized that was the optimum refrac strategy at a (much) later date nine years later! Read more...