Depositional and reservoir facies of the Mississippian Leadville formation, northwest Lisbon Field, Utah.

Abstract

The NW Lisbon field lies on the flank of a faulted anticline on the S edge of the Paradox basin in SE Utah. The field produces primarily from intercrystalline, moldic, and fracture porosity in Mississippian (Leadville) carbonates, with estimated recoverable reserves of 42.85 million barrels of oil and 7 billion m3 of gas. The carbonate sediments were deposited in shallow-marine to evaporitic supratidal environments. During and following deposition, the sediments were subjected to cementation, dolomitization, solution, uplift and a major period of subaerial erosion that followed deposition. The carbonates were subsequently buried and sealed by a thick Pennsylvanian evaporite sequence. Geological and geochemical evidence suggests that the petroleum was derived from the Mississippian sediments and migrated into the reservoir facies during mid- to late-Pennsylvanian time.-J.M.H.