Integrating the practices of locating, selecting, and acidizing fractures into one focused approach has provided successful results in wells in southern Mexico. Previously these methods handled independently have yielded unpredictable results.
The standard methods of locating fractures within a naturally fractured carbonate do not inherently help in determining which are the important fractures in the geological system. Neither do they indicate which fractures are actually open at a useful distance beyond the borehole wall and will be the main production contributors. Often the drilling processes make both minor and major fractures appear to have equal importance.
In southern Mexico, this network of fractures requires a combination approach to evaluate the candidates. This paper explains how combinations of deeper investigating NMR response, conventional logs, and image logs can be combined to narrow the selection of key fractures. Focusing the subsequent completions on specific fractures allow more investment in actual productive intervals making the stimulation more effective.
Concentrating on the properties of the fractures rather than the host rock enhances the stimulation with the new acid systems available. Focusing on the fractures that will take most of the acid during a stimulation job allows decisions to be made about perforation planning with respect to the other reservoir properties. Perforating decisions and or acid stimulation planning can be used to enhance the fractures not normally sufficiently stimulated. This also allows the decision criteria for perforating to be based around enhancement and final production. Case histories, exclusively from Mexico, demonstrating this technique will be presented, as well as examples of other practices and the results.