Online Journal for E&P Geoscientists

Khlaifat, Abdelaziz ^*1; Qutob, Hani ¹; Barakat, Naiem ¹
(1) Weatherford Oil Tool, Dubai, United Arab Emirates.

A large portion of produced natural gas comes from unconventional resources such as shale gas, tight gas and coalbed methane. The production of shale and tight gas reserves on a viable scale is faced with significant technological and technical capability challenges. However, as technology matures and demands for natural gas grow, unconventional gas projects have become commercially viable.

North America had set an excellent example in leading the way in unconventional resources recovery and technology development. In 1996, shale gas wells in the United States produced 0.3 tcf, 1.6% of US gas production; by 2006, production had more than tripled to 1.1 tcf per year, 5.9% of US gas production. By 2005 there were 14,990 shale gas wells in the US producing from more than 70 shale gas plays. A record 4,185 shale gas wells were completed in the US in 2007. Shale gas has become an increasingly important source of natural gas in the United States over the past decade, and interest has spread to potential gas shales in Canada, Europe, Asia, and Australia. One analyst expects shale gas to supply as much as half the natural gas production in North America by 2020.

The unconventional gas reserves have taken on a growing strategic importance in the Middle East. With nations throughout the region, that are deficient in natural resources, are turning to importing necessary fuels or wisely gathering renewable resources. Nowadays, oil and gas companies in the Middle East are gearing up to capitalize on what amounts to more than 3000 tcf of unconventional gas in place. Many unconventional reservoirs have low matrix permeability, and natural fractures may be necessary for economic production rates. Therefore, optimal development of many unconventional reservoirs requires knowledge of the optimal completions and stimulation methods, as well as understanding of the role of natural fractures in fluid flow.

It is very important for gas operators to follow well-defined screening criteria that help them to decide whether to go after shale gas reservoirs exploitation. A comprehensive analysis of different properties of shale gas reservoirs, including their: mineralogy, gas in place, TOC, thermal maturity, water saturation, stimulation treatment, and completion strategies, is presented. The presented screening plan, constructed based on the available literature, will be of great help to oil and gas operators to make a go/no-go decision on shale gas projects.