Exploration Strategies for the U.S. Rockies

Stephen A. Sonnenberg
Kerr-McGee, Denver, CO

Exploration for oil and gas in the U.S. Rockies is a critical component of meeting the rising demand for oil and gas. Resource assessments from various groups suggest abundant remaining resources in the Rockies.

During the 1990s, restructuring of the industry and a move towards low risk development drilling took place. Currently, several resource play areas are being developed that were the result of exploration in the 1970s and 1980s. Exploration is a critical aspect of finding new resource plays.

The Mesozoic of the Western Interior contains significant potential for several reasons. The Mesozoic section contains tremendous volumes of mature source rocks (organic rich shales and bedded coals) and reservoir rocks. Several transgressive-regressive (T-R) cycles create the potential for large conventional and unconventional traps (resource plays). Superimposed on these T-R cycles is the Laramide event which broke the Western Interior basin in the U.S. into many basins along with burying source and reservoir rocks. The burial in many cases caused significant degradation in reservoir quality (i.e. tight gas), matured the source rocks and created abnormally pressured systems. Tight reservoirs, shale, and coals are considered unconventional reservoirs and should be a focus of future exploration.

Exploration strategies should include the following: identification of potential basin center areas, analyses of geothermal gradients (most fields are associated with geothermal anomalies), abnormal pressure identification, visualization techniques, specialized maps, application of new technologies, and a study of commercial and minor or noncommercial occurrences of oil and gas.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005