Technology Focus: Tight Reservoirs (October 2014)
Authors: Kalfayan Leonard 
Published: February 2015

Technology Focus
Exploration and development of unconventional hydrocarbon reservoirs continue to grow at a pace that exceeds our understanding of the nature of these ultratight formations and how to sustain longer-term production from them. This is confounded further by the expansion of the industry into the broader and increasingly mysterious realms of liquid-rich and tight oil reservoirs beyond the relatively better- understood tight gas formations with their longer history of exploitation. With this greater breadth of activity, the unknowns, uncertainties, and challenges are increasing.
Already, estimates of unconventional hydrocarbon reserves have varied greatly, and the financial and future-energy-outlook implications of such wide-ranging uncertainty are enormous. With the industry moving forward with exploration and development in the broader categories of unconventional resources globally, it is of paramount importance to assess and improve the different methods and tools for estimating reserves, to establish their accuracy and credibility. And this must be accomplished in conjunction with increasing our fundamental understanding of unconventional formations at the nanoscale. This is a considerable challenge but one with significantly greater emphasis and efforts across the academic and industry research-and- development landscape.
In conjunction, there is increasing attention on addressing the immediate issue of rapid well-production declines from the often prolific, but short-lived, initial production rates. With that in mind, methods including the use of enhanced recovery fluids and well-pattern schemes, and reactive fluids such as acids in drilling, completion, and stimulation processes, are beginning to receive genuine consideration. The importance cannot be overstated because alternatives to hydraulic fracturing may become a necessity, at least in certain areas of the world. Through special core analysis and flow studies, visualization techniques, and simulation, acid stimulation in carbonate-rich tight oil formations (as one example) may find greater and more-creative application beyond the acid spearheads ahead of hydraulic-fracturing stages. Other strategies for enhancing production and extending production performance, such as through imbibition and post-stimulation shut-in strategies, especially in liquid-rich and tight oil developments, are receiving more attention and are providing new and important learnings, too.
The papers featured this month provide new insights and examples in some of these key, and exciting, areas of current focus in unconventional, tight oil and gas, and shale developments. The reader is encouraged to delve into these topics and continue to monitor progress, which is moving at a fast pace. JPT
Recommended additional reading at OnePetro: www.onepetro.org.
SPE 163814 Prediction of SRV and Optimization of Fracturing in Tight Gas and Shale Using a Fully Elastoplastic Coupled Geomechanical Model by M. Nassir, University of Calgary, et al.
SPE 167092 Evaluating Treatment Methods for Enhancing Microfracture Conductivity in Tight Formations by Philip D. Nguyen, Halliburton, et al.
SPE 167713 Water Loss vs. Soaking Time: Spontaneous Imbibition in Tight Rocks by Q. Lan, University of Alberta, et al.