When evaluating mud rock completions one is quickly struck with the complexity of the task. Mud rock "shales" by their very nature can be problematic to evaluate given the wide variation in geology, rock properties, and reservoir characteristics, not to mention the effect of multi-fractured horizontal well completions. Quite often, the reservoir characteristics between an economic well and an uneconomic well are very similar, further compounding the problem. So, what can we learn by taking another look at North American shale plays to help identify the more productive shales, improve economics and reduce the cycle time bringing this resource to market globally? Sometimes, the simple measurements we make at the wellsite can be very indicative of the things we don't measure very well, like the degree of natural fracturing and the interconnectedness of porosity. The subject material and the information discussed in this review was derived from the study of the characteristics and data from hundreds of completions with production results for shale wells in North America.
The findings presented show the results of formation evaluation and analytical evaluation which have proven to be good indicators of well productivity and hydrocarbon recovery. Many of these methods have been underutalized by the industry for shale evaluation and completion optimization.
Past successes in unconventional resource arenas are sometimes viewed as the result of seredipity. However, that has not been the case – past successes have evolved, in some cases over periods of years. A comparison of learnings from the Bakken and Eagle Ford show some interesting commonalities that help identify economic wells from subeconomic wells, as well as the most productive completion intervals in lateral wellbores. These findings and evaluation methodologies can readily contribute to the global hunt for unconventional reservoirs, and evaluation / optimization of their development strategy..