Unconventional Resource Recovery Improvement Using Conventional Reservoir Engineering Strategies

Roundtree, Russell¹
 Sedillos, Lia²
 Wright, John³
 Miskimins, Jennifer⁴

Conventional resources follow a very different reservoir development process than do most unconventional resource plays. In the case of the numerous tight gas and shale gas plays in

, maximizing the profitability of the individual well being drilled dominates the development strategy compared to maximizing overall resource recovery. Most conventional resources utilize a workflow that incorporates optimizing the overall reservoir recovery and rolls the field-wide economics into the decision making process.

Unconventional resources usually require stimulation. Often, the biggest challenge is not finding the productive zones as much as finding the zones that are most conducive to effective stimulation. Optimizing hydraulic fracture treatment characteristics, zone-by-zone, often determines the degree to which the available resource is recovered. In practice, however, fracture treatment parameters are often selected that produce profitable wells but leave behind considerable hydrocarbon resources.

In low permeability reservoirs well placement decisions can have dramatic effects on field-wide reservoir drainage if stimulation patterns are not well understood. Unconventional resources often begin development with a low drilling density and are down-spaced as reservoir understanding increases. Utilizing development drilling strategies that conform to the plethora of technical constraints while maintaining the option of efficient down-spaced drilling options in the future is particularly challenging. Often, resources are stranded and become impossible to economically recover at some future date.

This paper will show, via models and actual field results, how unconventional resource developments, while pursing profitable wells, often do so at the expense of leaving considerable bypassed resources behind that will never be economic to recover. These decisions can result in sub-par overall economic performance for the operators utilizing this strategy. Some emerging technologies and workflows are discussed that enable more efficient exploitation of unconventional tight gas and shale plays and maximize the ability to improve the recovery factors of most unconventional resource plays.