In the recent past, once a gas reservoir had been discovered and delineated,  development would routinely proceed with the drilling of wells to a pre-determined spacing, and production of these wells to depletion. Unlike oil reservoirs, which were known to leave large volumes in the ground that could only be produced through Secondary and Tertiary recovery techniques, it was generally not appreciated that large volumes of gas might remain between, beneath, or behind the casing of the existing wells. However, in the early 1980s, the Department of Energy, in conjunction with industry and academic partners, successfully introduced the concept of secondary recovery into the gas industry.  

DOE-sponsored work in the Texas Gulf Coast helped foster the awareness that premature pressure loss, avoidable formation damage, and inefficient infill drilling practices were wasting large volumes of the nation’s gas resource. For example, advanced technologies that had previously been limited to exploration applications, such as 3-D seismic and vertical seismic profiling, were found to be helpful in delineating the stratigraphic complexities that hindered complete gas recovery. In the years following the study, recovery efficiencies in the targeted districts jumped nearly 30 percent. Recently,  NETL has expanded these efforts to the offshore fields in the Gulf of Mexico and to large, mature fields in Appalachia, with similar results.

Currently, NETL is pursuing projects to extend the concepts of secondary gas recovery to unconventional reservoirs.  For example, a recent project in the San Juan Basin of New Mexico has shown that significant volumes of additional reserves can be added to developed fields by tailoring infill well patterns to interpreted trends in reservoir heterogeneity.