Rebound Hardness: Relationship to Facies, Mineralogy, Natural Fractures, Reservoir Quality, and Rock Mechanical Properties, the “Mississippian Limestone” Play, North-Central Oklahoma, USA

Wang, Yulun (Oklahoma State University) | Grammer, G. Michael (Oklahoma State University)


ABSTRACT: Rebound hardness (RHN) has recently gained considerable interest as a rock mechanical parameter in the petroleum industry. However, few published studies target a comprehensive integration among RHN and reservoir parameters, which can be highly valuable in reservoir characterization and production. This study focuses on the integration among RHN and facies, mineralogy, natural fractures, reservoir quality, and rock mechanical properties of the unconventional “Mississippian Limestone” play in north-central Oklahoma, USA. In 2415 feet (736 m) of core, RHN correlates with porosity, permeability, and critical rock mechanical properties, suggesting its potential value as a quick and inexpensive tool in reservoir characterization and production design. RHN exhibits varying patterns in relation to porosity and permeability in different play areas, likely related to different depositional settings and sampling bias. Therefore, the prediction of reservoir quality from RHN should be tailored among different play areas with a well-defined sampling protocol. Results also indicate that RHN correlates well with mineralogy but exhibits limited variability among many fractured and non-fractured zones. This suggests that the present-day rock mechanics are likely a combination of earlier “unaltered” and later “altered” characteristics, indicating that the temporal evolution of rock mechanical properties should be considered in reservoir characterization and production design.


The “Mississippian Limestone” Play, located primarily in Oklahoma and southern Kansas (Figure 1), has been developed using conventional vertical drilling techniques for over half a century and has recently become one of the most active unconventional resource plays in North America. The associated strata - the “Mississippian Limestone” (MISS) - is an informal stratigraphic nomenclature which includes the Mississippian (Early Carboniferous)-aged strata present across the U.S. Southern Mid-Continent, including parts of Kansas, Missouri, Arkansas, and Oklahoma (Figure 1). As opposed to the historic “Mississippian Limestone” play, there are several recently discovered play areas nearby that target the Mississippian section, such as the “STACK” play southwest of the “Mississippian Limestone” play area (Figure 1).