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The AAPG/Datapages Combined Publications Database
The enormous gas resources locked in the various Mississippian and Devonian shale layers of the major eastern geologic basins naturally attracts the interest of energy policy makers and commercial entrepreneurs who are motivated to see and participate in the exploitation of that fraction which can be easily recovered. To succeed in this endeavor, however, certain constraints have to be faced, and other nagging problems have to be resolved. This paper classifies the constraints and the problems so that they can be dealt with systematically, and so that the expectations will not overtake the prospects and the realities.
The fact that the shale gas resource is widespread, and indeed reasonably evenly spaced, must be weighed against the observation that so far very few ways have been found to achieve high levels of prolonged production even from the historic reservoir locations. The obstacle that most appears to limit recovery is the fact that the shale matrix which holds much of the gas has the character of a molecular sieve. This means that somehow transport paths must be induced (especially when they do not naturally preexist) so that gas can easily move toward the wellbore sinks. Completing shale wells with stimulations that induce fractures and other types
of rubble, and which otherwise break down the formation to increase the effective wellbore radius, frequently will be indicated.
Another major obstacle is the necessity of minimizing skin damage resulting from the drilling, completion, and stimulation processes. A third obstacle has to do with economics which is dependent on the cost-effectiveness of the exploration and exploitation procedures that are followed in particular cases. Although it would be convenient to have evidence that a high selling price (e.g., due to market demand) would circumvent the major constraints and avoid the attending problems, the evidence points on the contrary to the need for achieving a technologic breakthrough before the full impact of economics will be felt.
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