Evaluating Potential for Induced Seismicity Through Reservoir-Geomechanical Analysis of Fluid Injection in the Arbuckle Saline Aquifer, South Central Kansas
The Cambro-Ordovician Arbuckle Group consists of laterally extensive shelf carbonates that unconformably overly Proterozoic basement or Cambrian strata. The thickness (~200 to 1400 ft), relatively high permeability (10 to 1500 mD), depth (>3500 ft), and naturally low pressure (below hydrostatic) of the Arbuckle have made it an ideal target for UIC Class I and II injection in Kansas, and more recently for proposed injection of CO2 for long-term storage (Class VI). However, a recent increase in the frequency and size of earthquakes in Harper and Sumner counties, southern Kansas, where coproduction and disposal of brines associated with development of the Mississippian play has been most active, has elevated concerns about the relationship between fluid injection and seismicity. To evaluate the impacts of fluid disposal within this area of recent seismicity and possible mitigating strategies, we are constructing a geologic model of the Arbuckle in Petrel™. The model will incorporate detailed stratigraphic and reservoir property analysis (e.g., φ, Sw, Vsh, k) of ~24 wells, covering a 600 km2area. The porosity of the Arbuckle will be estimated using multi-mineral quantitative formation evaluation, whereas the permeability of the formation will be estimated using a neural network, fuzzy logic, or alternative method pending availability of core data. The model will also incorporate faults identified from analysis of regional structure contour and isopach maps and potential field data. The geologic model will be upscaled into a dual-permeability compositional model for simulation in CMG™, which will be used to estimate changes in pore fluid pressure, the vertical and lateral extent of disposed fluids, and geomechanical stability of the formation. The geologic and simulation model could provide stakeholders tools and information to guide mitigation should seismicity in the area exceed thresholds established by the Kansas Seismic Action Plan.
AAPG Datapages/Search and Discovery Article #90216 ©2015 AAPG Annual Convention and Exhibition, Denver, CO., May 31 - June 3, 2015