Meeting the Pinedale Challenge
John Bickley, Candyce Beck Brake, Mike Caputi, Floyd Doughty, Paul Huckabee, Bud Johnston, Edwin Quint, and Robert Whale
Shell E&P Co., Houston, Texas
Shell’s Tight Gas Task Force (TGTF) was formed to find, develop, and implement technologies that would assist in unlocking natural gas resources from ultra tight reservoirs (>.01 milidarcies) in North America. The initial focus of this team was to address technology issues related to optimal development of Shell’s leases located in the Pinedale Field of southwestern Wyoming.
The Pinedale field, located in Green River basin of southwest Wyoming is a thrusted, asymmetrical anticline, with 2000’ (610 meters) structural relief and aerially is 35 miles (56 km) long and 6 miles (10 km) wide. The primary productive interval is the Maastrichtian age Lance formation comprised of 5,500’ (1692 m) of stacked fluvial sands with the productive interval depths ranging between 7,500’ (2286M) and 14,000’’ (4267m). Reservoir porosities average 8% and permeabilities range from 1-10 micro Darcys; pressure gradients range from .5 to 85 Psi. USGS gas-in-place volumes for the entire anticline are estimated to be 159 TCF. The field is currently being developed on 40 acre (402 meters) spacing with Shell having variable working interest in over 550 locations. Significant efforts are actively in progress that may ultimately result in the entire anticline being developed on 20 acre spacing.
Clearly much has been published as to the criticality of cost management and mechanical efficiency if these types of resources are to be profitably recovered. However it is our experience that to achieve step function profitability improvement it is equally important to maximize understanding of the subsurface and related drilling and completion processes. Further more, we believe for this type of profitability improvement to be achieved it requires a highly integrated effort between those in the field developing the resource, combined with an integrated, applied research and development (R&D) effort focused on pushing the boundaries of existing technologies as well as developing and implementing of new and emerging technologies.
Shell’s technology focus areas for unleashing tight gas potential are: sweet spot identification using seismic, drilling optimization focused on horizontal drilling and under balanced coiled tubing drilling, completion optimization focusing on improved hydraulic fracture designs and improved reservoir performance monitoring and prediction capabilities. Several examples associated with improved subsurface understanding and drilling and completion optimization will be discussed that clearly demonstrate bottom line impact of technology.
Finally, a clear learning from this effort is that no single “silver R&D bullet” exists that addresses the technical challenges faced with producing gas from ultra low permeability reservoirs, rather the use of an integrated R&D approach is a key ingredient to success. Also, it is equally important to have a high level of asset support to evaluate, execute, and deploy new technologies in the field.