Revisiting the Subsalt Trap Archetype Classification Scheme After Eight More Years of Gulf of Mexico Subsalt Drilling

摘要

Subsalt exploration in the Gulf of Mexico (GOM) remains an area of intense focus by the oil and gas industry. Successfully accessing economic hydrocarbon accumulations beneath the extensive allochthonous salt sheets in the northern GOM basin requires solving a number of geophysical, geological, and drilling challenges. In 2001, Hart and Albertin presented a geological tool which, given imaging challenges associated with complex allochthonous salt, could be used for qualitatively ranking subsalt exploration prospects according to their structural attributes. The ranking scheme proposed by Hart and Albertin is comprised of a collection of subsalt trap archetypes, each archetype representing an important structural variation with specific trap merits and risks. These archetypes are grouped into four genetic play families, calibrated for overall prospectivity by a statistical analysis of subsalt well success rate. The statistical analysis in 2001 used a database of 69 subsalt wells; since then, at least 122 new subsalt traps have been drilled by the industry. We used this new subsalt well data to revisit the classification scheme and answer a few specific questions: does the trap family priority hold up given the subsalt successes and failures of the past eight years, do the original archetypes still represent the full range of observed salt styles, and are any revisions to the classification scheme warranted?