I came across a good AAPG presentation put on by Jesse Gilman and Chris Robinson of SM Energy. It is called Success and Failure in Shale Gas Exploration and Development: Attributes that Make the Difference. It dissects the current methodology for evaluating shale reservoirs using characteristics such as TOC, Ro and thickness. The results are interesting and fit with some of the analysis we have done.
First, you hear all the time the importance of thickness. While in general thicker rock will provide better results, this is true only to a point. We studied the Barnett extensively and discovered that there is a point in which the incremental gains become negligible. Below is their slide detailing the correlation (or lack thereof).
Furthermore, they discovered that conventional vitrinite reflectance ranges need to be modified, up to 3% is the best range in shale-gas. Even more interesting is a correlation involving EUR/stage to temperature gradient.
They mention a few theories, one is vitrinite reflectance measures max temperature, not how long the rock has been cooking. Therefore just because there is a nice vitrinite reflectance, does not mean the rock has been cooked for an optimal time, ie “Brisket Theory”. The other is that higher temperature gradients could lead to enhanced dewatering.
Finally, they discuss the effect faulting has on production. The theory is that faults hog the frac energy resulting in ineffective stimulations.
Good stuff by these guys definately worth the read, make sure to read the presenters notes at the bottom.
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