Niobrara Gas in the Eastern DJ Basin: Components of Economic Development

Bruce Kelso¹, Jeanette B. Dubois¹, Charles R. Durkoop¹, and Dan Donoho^2
1Berry Petroleum Company, Denver, CO
²Donoho Oil & Gas Consultants, Evergreen, CO

Drilling for shallow, low pressure natural gas resources of the Cretaceous Niobrara formation chalk facies is expanding beyond productive limits of existing fields in the eastern Denver-Julesburg Basin. To improve both the economics and success rate of the gas play, Berry employs petrophysical characteristics determined by analogy with economically productive wells, regional trend maps, 3D seismic data, coiled-tubing drilling and effective practices to handle water production along with gas.

Reservoir parameters associated with economic levels of production are primarily identified using resistivity and neutron/density wireline logs. Crossplots between estimated ultimate recoveries (EURs) and resistivity, porosity gas effect, hydrocarbon pore volume and elevation data are utilized to establish productivity indicators. Mapping various reservoir parameters helps to establish regional trends for high-grading future development opportunities.

Seismic data plays a key role in both the exploration for new Niobrara gas accumulations and the ongoing development of existing fields. Areas marked as prospective for future development benefit from 3D seismic data by the identification of structural highs, fault location, magnitude of displacement and amplitude variations. The 3D seismic data define ‘local controls’ which aid in the placement of well locations, the number of wells that can be drilled, and ranking the drill order based on productive risk. These capabilities are not possible from a regional investigation alone.

Use of coiled-tubing drilling rigs has positively changed the activity pace of the Niobrara gas play and reduced the foot-print of well pads on agricultural lands. Costs are very competitive, partly due to reduced drill times, averaging about one day down from two-and-a-half days, and economies of scale.

AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas