Reservoir and fracturing engineering challenges in tight gas development

Development of tight gas in continental North America has a long history. Some of the early attempts at stimulating and producing economically from microdarcy formations date back to the 1970s (Holditch et al., 1971, Fast et al., 1977, Wyman, 1980). The US price incentives in the Natural Gas Policy Act of 1978 spurred technology development, most notably massive hydraulic fracturing (MHF). Since then improvements in fracturing technology have continued unabated. Horizontal wells and more recently multi-stage hydraulically fractured horizontal wells represent the state of the art. Continued improvements in exploration/imaging tools, and advances in reservoir engineering interpretation techniques have helped identify what is actually occurring in the field. All of these factors have made tight gas a significant part of the current North American gas production. Kuuskraa (2006) estimated that unconventional gas (including tight gas, coalbed methane and shale gas) accounted for 40% of US natural gas production in 2004, and is rising every year.