The Impact of Local Stress Field Orientation On Pressures Encountered During Waste Injection Operations In the Ivan River Field, Alaska

K. Zaki; S. Marinello; A. Algarhy; A. El-Fayoumi; Z. Zhai; A. Abou-Sayed; G. Simon; C. Walsh; M. Lynch; L. Greenstein; T. Hillegeist
44th U.S. Rock Mechanics Symposium and 5th U.S.-Canada Rock Mechanics Symposium, Salt Lake


The Ivan River Unit is a remote onshore gas field located in the northwest side of the Cook Inlet basin, in south-central Alaska. Class II drilling and production waste is disposed of onsite. Lack of service roads and accessibility during the winter limit other waste-handling options. Many of the disposal injection wells in the region are recompleted abandoned production wells. Wells that were directionally drilled to production targets may be oriented sub-optimally for injection purposes. Regionally, injection pressures have been low initially, with an increasing trend consistent with the volume of waste injected. It was, therefore, unexpected when unusually high injection pressures were encountered in the Ivan River Unit. The pressures recorded were in excess of the overburden stress and 1400 psi above those predicted in the feasibility study. A geomechanical assessment included a survey of published stress orientation data for the area, which indicated that the principle horizontal stress is oriented sub-perpendicular to the azimuth of the deviated injector wellbore. This orientation would require higher injection pressures due to multiple factors. The model was benchmarked against the injection history, leakoff and step rate test data provided. An assessment of breakouts in a nearby field confirmed the principle stress orientation and its potential effect on fracture orientation and the resultant injection rates and pressures.