A Geomechanics Updates on Alaska’s GNI Project: Monitoring, Assessment, Validation and Assurance for the World Largest Drill Cuttings Injection Project
Abou-Sayed, A.S. and Wang, G.G. Advantek International, Engle, H. BP Alaska, Willson, S.M. BP, Bill, M. ASRC Energy SErvices
40th U.S. Symposium on Rock Mechanics (USRMS) Rock Mechanics for Energy, Mineral and Infrastructure Development in the Northern Region, June 25-29, 2005, Anchorage, Alaska
The ongoing Prudhoe Bay Grind and Inject (GNI) program began in the mid 1990’s. State and Federal Environmental regulations require the operator to assure the injected material not be allowed to migrate to groundwater aquifer zones or to the surface. Sensitive fracture modeling and annual surveillance activities have been conducted to ensure the integrity of the process. A recent extensive technical review of the field’s collected information, injection simulation results and well testing data was conducted to evaluate the containment of the injected slurry. The current paper discusses the results of engineering simulation and field monitoring efforts within the perspective of a geomechanics review to verify the injected slurry extent. Novel interpretations of pressure records along with new simulation results are presented. Analysis of the waste domain simulation, based on fracture propagation in compactable (soft) rocks and well testing data, confirm that the fracture domain is confined in the intended injection zone. This paper will also compare the results of successive fracture domain simulations to the results of annual well tests over the last 5 years. Finally, the applicability of other potential means of disposal domain monitoring and diagnostic tools such as surface and downhole tiltmeters, micro seismic diagnostic, and tracers, are assessed from a geomechanics perspective.