The Mississippian-Devonian Bakken Formation is a relatively tight mixed carbonate – clastic sequence in the Williston Basin of North Dakota. Although production can exceed 1000 BOPD, hydraulic fracturing is necessary to induce economic production. In late 2007 seven (7) operators along with Schlumberger formed a consortium for the purpose of applying the best available technologies to examine the geologic factors and the drilling and completion principles that affect production. As part of this, three (3) horizontal wells (each 4000 feet in length) were drilled 1500 feet apart into the Middle Bakken Member. Schlumberger positioned an array of 16 triaxial geophones, spaced 100 feet apart, in the middle lateral (Nesson State 42X-36) to monitor the microseismic activity during the hydraulic fracturing of the two (2) outside wells. Different hydraulic fracturing methods were applied in each stage; ranging from a single treatment in the northern lateral (Nesson State 41X-36) to a six (6) staged treatment with swell packers in the southern lateral (Nesson State 44X-36). The microseismic events were studied in the context of our geologic understanding of the area, comparison to the distributions of radioactive and chemical tracers and a reservoir simulation to develop a robust interpretation of effectiveness of the hydraulic fracture treatments. In addition to the microseismic monitoring conducted by Schlumberger, three other microseismic monitoring arrays were installed and monitored. The results of the various monitoring efforts varied dramatically and these differences are worthy of examination.

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