ALASKAN HEAVY OIL: FIRST CHOPS AT A VAST, UNTAPPED ARCTIC RESOURCE

This paper describes a cold heavy oil production with sand (CHOPS) flow back and a multi‑zone drill‑stem test undertaken to characterize a large, untapped, extra heavy oil resource on Alaska's North Slope for commercialization. Application Although the resource is found in multiple reservoir zones extending across the basin, initial appraisal focused on the deeper, less viscous oil in the east which was believed to be suited to for "cold" production techniques that exploit solution gas drive. Suitability of reservoir fluids for cold production is difficult to quantify due to high oil viscosities & unconsolidated reservoir sands. Due to the surface environment, significant well construction and artificial lift design challenges also exist. Reservoir access, balanced with effective solids transport along the wellbore are key considerations in for future CHOPS or horizontal well development and needed to be better understood. Results, Observations, Conclusions A 2008 flow back to test the viability of CHOPS recovered the first significant quantities of 11‑12 API oil at minimal drawdown and 5‑40% sand over a 3‑week period. In a separate appraisal well, PVT quality fluid samples were obtained from 2 additional sands with a drill‑stem test that provided crucial information to characterize the reservoir. Based on the appraisal data gathering, the following conclusions can be made about developing the resource: 1.Exploitation of the resource is technically possible using cold production techniques. 2.Formation permeability and dissolved gas suggest that massive sand production may not be required for effective primary production. 3. Well design & artificial lift must be centered on managing fluid viscosity and transporting produced solids. Significance of Subject Matter. Understanding reservoir properties in unconsolidated, heavy oil reservoirs is challenging, but essential in appraising the resource. Collecting quality data early in is crucial to unlocking this large, unconventional resource.