Characterizing the Potential for Injection‐Induced Fault Reactivation Through Subsurface Structural Mapping and Stress Field Analysis, Wellington Field, Sumner County, Kansas. Issue 12 (13th December 2017)

• Record Type: Journal Article
• Authors: Schwab, Drew R.; Bidgoli, Tandis S.; Taylor, Michael H.
• Is Part Of: Journal of geophysical research. Volume 122:Issue 12(2017)
• Page Start: 10, 132
• Page End: 10, 154
• Publication Date: 2017-12-13
• Subjects: in situ stress -- drilling induced fractures -- induced seismicity -- CO2 storage -- carbon sequestration; Geomagnetism -- Periodicals; Geochemistry -- Periodicals; Geophysics -- Periodicals; Earth sciences -- Periodicals; 551.1
• DOI: 10.1002/2017JB014071
• Languages: English
• ISSNs: 2169-9313

Abstract

Abstract: Kansas, like other parts of the central U.S., has experienced a recent increase in seismicity. Correlation of these events with brine disposal operations suggests pore fluid pressure increases are reactivating preexisting faults, but rigorous evaluation at injection sites is lacking. Here we determine the suitability of CO2 injection into the Cambrian‐Ordovician Arbuckle Group for long‐term storage and into a Mississippian reservoir for enhanced oil recovery in Wellington Field, Sumner County, Kansas. To determine the potential for injection‐induced earthquakes, we map subsurface faults and estimate in situ stresses, perform slip and dilation tendency analyses to identify well‐oriented faults relative to the estimated stress field, and determine the pressure changes required to induce slip at reservoir and basement depths. Three‐dimensional seismic reflection data reveal 12 near‐vertical faults, mostly striking NNE, consistent with nodal planes from moment tensor solutions from recent earthquakes in the region. Most of the faults cut both reservoirs and several clearly penetrate the Precambrian basement. Drilling‐induced fractures ( N = 40) identified from image logs and inversion of earthquake moment tensor solutions ( N = 65) indicate that the maximum horizontal stress is approximately EW. Slip tendency analysis indicates that faults striking <020° are stable under current reservoir conditions, whereas faults striking 020°–049° may be prone to reactivation with increasing pore fluid pressure. Although the proposed injection volume (40, 000 t) is unlikely to reactive faults at reservoir depths, high‐rate injection operations could reach pressures beyond the critical threshold for slip within the basement, as demonstrated by the large number of injection‐induced earthquakes west of the study area. Key Points: Faults within the Arbuckle Group reservoir are conductive and penetrate the Precambrian basement Mapped faults are critically stressed at depths typical for earthquake hypocenters in southern Kansas and northern Oklahoma Reservoir‐based slip tendency analysis may be inadequate for assessing reactivation potential of basement faults in the central U.S.