To complete the Marcellus shale's horizontal wells simply and cost-effectively, operators typically use geometric perforation designs in order to prepare for hydraulic fracturing. With this technique, perforation clusters are placed at equidistant points along the lateral. However, microseismic monitoring shows that this type of stage selection often distributes hydraulic fracturing treatments unevenly. The fracture treatments propagate to the lowest-stress intervals, leaving a large number of perforations under stimulated or simply unstimulated. In an attempt to improve on this technique, a study was performed in which wells using an engineered perforation design were compared against offset wells that had a geometric perforation design.

For the wells employing an engineered design, an acoustic scanning tool was deployed on wireline and mechanical rock properties were obtained along the length of the productive lateral. The critical well information, including in situ stress, lithology, Young's modulus, and Poissons Ratio enabled engineers to create custom staging and perforating designs. These designs were optimized to provide more consistent stimulation along the entire lateral, and lower breakdown and treating pressures. The final result of using the engineered perforation design was a significant increase in production when compared to conventionally completed wells.

During the stimulation treatment of the engineered perforation design, there was a significant drop in the average treating pressures during fracturing when compared to geometric offsets. This was due to several factors including the fact that perforations targeted lower stress intervals. In addition to lower pressures, an elimination of premature job terminations or "screen-outs?? was seen. This occurs when pressures increase to such a degree that the stimulation treatment cannot continue within acceptable pressure ranges. Previous treatments in offset wells yielded a 35% screen out rate which resulted in significant lost time and additional costs.

The process and production results of wells completed with geometric perforations to wells with engineered perforations.