2021 GSOC October Meeting

Importance of Recognizing Preexisting Fractures to Completion and Production Efficiencies in the Marcellus Shale.

Dr. Tim Carr

Abstract

The Marcellus Shale Energy and Environmental Lab (MSEEL) provides a publicly available dataset and a hypothesis-driven field test of the significance of preexisting natural fractures at multiple scales on the effectiveness of the stimulation of an unconventional reservoir. Sonic and micro resistivity imaging show the presence of numerous preexisting cemented fracture swarms is evaluated. Natural fracture intensity in the Boggess 5H and MIP 3H were interpreted based on wireline and LWD image logs showing that 1000’s of calcite and bitumen cemented, but weak, fractures are present along the laterals as swarms that are at an angle to the present-day stress regime. Fractures with complex bitumen and calcite filling were recognized in core at the micro and macroscales (micron to millimeter). The importance of pre-existing fractures geometric stimulations was evaluated and compared to cluster that avoid intense pre-existing fractures using fiber-optic DAS/DTS data and supported by production and simulation. Fiber-optic DTS and DAS measurements coupled with wireline and LWD image logs from the lateral to recognize preexisting and cemented fractures. This data is supplemented with core analysis including (CT and thin sections) from vertical pilot wells show that clusters in parts of a stage dominated by preexisting fractures have significantly more hydraulic fracture activity to the point that other clusters appear largely inactive. In addition, processed fiber-optic data indicates that preexisting fractures can form near-well bore leak-off pathways to previous stimulated stages. Both can lead to stimulation and subsequent production inefficiencies. Two wells (Boggess 1H and 3H) that attempted to avoid preexisting fractures showed a significant increase in fracture stimulated volume based on decline curve analysis and micro seismic. Production history and simulated future production, support the conclusion that avoiding preexisting fractures in the Marcellus Shale can increase estimate ultimate production. We present conclusions about stage and cluster spacing and the significance of preexisting natural fracture on stage isolation and fracture efficiency. The publicly available data and workflow allow others to use, verify, and evaluate our findings using the same initial data.

Biography

Dr. Timothy R. Carr came to West Virginia University in 2007 as the first Marshal Miller Energy Professor in the Department of Geology and Geography. Dr. Carr is also a visiting professor at the China University of Geosciences in Wuhan and consultant to the private sector and the US State Department. He is a past President of the Council Energy Research and Education Leaders (CEREL) and the Eastern Section of the American association of Petroleum Geologists (AAPG). Current research projects are in the areas of unconventional resources, subsurface petroleum geology and geophysics, energy systems, and carbon capture and storage. Prior to coming to West Virginia, Carr worked as chief of the Energy Research Section and as senior scientist for the Kansas Geological Survey at the University of Kansas. He was also co-director of the Energy Research Center and adjunct professor in the University of Kansas, Department of Geology. His experience also includes 13 years with Atlantic Richfield (ARCO), where he worked in a number of research, operations and management positions. At ARCO, Carr was involved in both exploration and development projects in locations including Alaska, the North Sea, East Greenland, California and Kansas. He was a founder of a company focused on carbon storage and associated enhanced oil recovery. Carr has a bachelor’s degree in economics from the University of Wisconsin, a master’s in geology from Texas Tech University and a doctorate in geology from the University of Wisconsin.