ABSTRACT: Knowledge of the direction of hydraulic fractures can impact reservoir management in fracture stimulated reservoirs. Fracture direction can affect where wells are placed for optimum drainage (especially in-fill wells), how fracture treatments are designed, and how well patterns for EOR floods are designed. In-situ stress direction is especially important in the drilling of horizontal wells in order to determine the optimum direction of the wellbore with respect to well bore stability and intersection of the wellbore with hydraulic and natural fractures. Reliable, cost-effective methods for determining fracture direction can aid production engineers and reservoir engineers alike in optimizing production from fields stimulated through hydraulic fracturing and/or developed with horizontal wells.
This paper details a study of in-situ stress and hydraulic fracture direction in the Hugoton, Panoma, and South Cutter fields in Kansas and Oklahoma. Data were collected in 6 wells across the field in the Chase, Council Grove, and Chester formations to determine in-situ stress and hydraulic fracture orientation. The azimuths of hydraulic fractures (determined from tiltmeter surveys and passive borehole seismic measurements) compared well with the orientation of maximum horizontal in-situ stress (determined from shear acoustic anisotropy and strain relaxation measurements).
Of the six wells studied, four suggest an azimuth of maximum horizontal stress between 90° and 98°. The data suggest that the east-west regional compressive stress trend for the southern mid-continent area (Zoback, 1992b) continues at least as far north as mid-Kansas. The orientation of stress in the other two wells appears to be affected by local faulting in the area. The data will be used to help choose in-fill well locations to maximize drainage and to determine the most advantageous orientation of horizontal wells.
