Optimized Hydraulic Fracture Design: Using High-Resolution Borehole Images for 3-D Structural Delineation in Horizontal Shale Wells

Abstract

Designing and executing an optimized well completion design is of top priority for operators in unconventional plays. High-resolution wellbore image data is critical in identifying structural features that can significantly impact hydraulic fracturing effectiveness. Quanta-Geo, a new imaging technology, paired with eXpandBG, a well-centric structural modeling workflow, provides a new level of detail in reservoir analysis. Interpretation of Quanta-Geo images can identify, characterize, and map faults, fractures, and rock texture, allowing for smart completion design and, ultimately, increased production. This study focuses on lateral wells drilled into the upper Eagle Ford Shale play in South Texas, USA, where 3D seismic data has been acquired and interpreted. Faults, both regional and sub-seismic scale, are common across the acreage. There is also multiple water bearing zones overlying and underlying the target interval. The key to successful field development in this area is to distinguish which faults may present a hazard while drilling or during the stimulation process. If a wellbore is connected to a water hazard (via fault or hydraulic fracture), it has a high potential for failure. The first two wells in this area were stimulated without detailed analysis of the image logs. The end result was two wells drilled parallel off of the same pad that cost over $6MM each and a) produced with over a 95% water cut and b) failed to meet economics by a significant margin. Subsequent wells used the interpretation of the Quanta-Geo data to optimize the frac design. A significant fault was identified and appeared to be a potential hazard for water influx into the wellbore. This time, the operator attempted to mitigate the risk of water production by implementing a 350 foot safe zone on both sides of the subject fault during the completion and stimulation planning phase. The result for these wells was more positive as both produced at a normal water cut and showed no indication of a connection to water zone. This study provides a clear demonstration of how sub-seismic scale structural features can significantly affect well performance. High resolution image data upscaled to a well-centric structural model is critical to success in these wells. Completion designs that incorporate these models are essential to maximize production.

AAPG Datapages/Search and Discovery Article #90216 ©2015 AAPG Annual Convention and Exhibition, Denver, CO., May 31 - June 3, 2015