With drilling on the rise, there is a growing belief that better understanding of the effectiveness of completion designs and hydraulic fracturing strategies will require far greater subsurface geological understanding. Moreover, continued well productivity improvements will only be realized through improved reservoir characterization, and by applying formation petrophysical and geomechanical information to optimize methods of drilling, completing, and stimulating wells.
Given the nonhomogeneous nature of the geology in unconventional reservoirs, applying vertical offset well logs and interpolating field reservoir models is generally accepted as a good start, but hardly the complete solution. Geometric completions and fracturing strategies are not practical or effective in these unpredictable heterogenous environments. Along the wellbore, operators are encountering highly variable rock properties that affect fracturing efficiencies, and result in poor or unexpected well production results.
This trend is forcing producers to evaluate stage-by-stage production contributions. They are finding that large portions of their wells are not contributing. There is a growing realization that improved well results that are repeatable and predictable are only going to come about by enhancing production at every stage in the wellbore. This requires engineered completions programs and tailored fracturing strategies that account for the considerable rock heterogeneity along the lateral.
Operators are not simply seeking open hole logs. They want to translate formation evaluation measurements into useful insights that enable them to adjust their fracturing and completions strategies. They are looking for ways to incorporate subsurface geological data into practical operational applications that improve fracturing efficiencies and maximize well productivity. For example, various related well data sets—such as cuttings analyses, gas detection, tracer surveys, and actual pumping records—are overlaid to provide a full view of why actual well productivity may be different from the anticipated. This way, a continuous improvement process can be implemented.
Although repeatable and predictable results have been elusive, some well productivity success has been demonstrated. However, with so many variables to the recipe, most observers agree that exploiting shale is more of an art than a science.