Relating Sonic Velocities, Minimum Horizontal Stress, and Natural Fracture Distribution to Stimulation Efficiency during Completion of the Marcellus Shale MIP-3H Unconventional Well, West Virginia, USA

Log data from the Marcellus Shale Energy and Environment Laboratory (MSEEL) was acquired along the lateral of the MIP-3H well. This unconventional shale-gas well was completed within the Marcellus Shale just above the Cherry Valley Limestone, a thin limestone member separating organic rich units of the Marcellus. The geomechanical moduli, Poisson’s Ratio (PR) and Young’s Modulus (YME), were generated using compressional and shear sonic logs to indicate zones of increasing brittleness for each of the 28 stages along the 6124 ft. (1867m) horizontal lateral. Brittle reservoir rock is more readily fractured during hydraulic stimulation than more malleable rock. Stages with geomechanically homogeneous clusters were more likely to have evenly distributed energy during stimulation. Natural fractures formed during maturation of the Marcellus Shale are interpreted to have initiated during the Permian and are distributed along the wellbore. The contrast between calcite and shale in Schlumberger Quanta Geo logs facilitated fracture identification, and 1600 calcite-filled and a few open pre-existing fractures were recognized along the horizontal portion of the well. Research conducted suggests that all pre-existing fractures are reactivated during hydraulic stimulation and contribute to the complex fracture network. Because these fractures are reactivated during the hydraulic fracturing process, natural fracture intensity and distribution within stages can impact the efficiency of stimulation. Minimum horizontal stress (Shmin) is an important factor to consider in the completion process. Cluster placement at locations of equal or similar Shmin allows for fracturing fluid to more evenly disperse across all perforations. Hydraulic stimulation data were obtained with the use of a fiber optic cable. The distributed acoustic sensing (DAS) data allows for a comparison of the energy distribution during stimulation. Comparing geomechanical properties of individual stages to the apparent stimulation efficiency shown in the DAS data can result in improved methods of well completion. This would lead to more geologic approaches to stage and perforation completion rather than geometric. Increased stimulation efficiency could increase production and estimated ultimate recovery from unconventional shale-gas reservoirs