Kevin R. Evans¹, James F. Miller²

(1) StratiGraphix, Aptos, CA
(2) Southwest Missouri State University, Springfield, MO

ABSTRACT: Correlating Outcrops with Potential Oil and Gas Reservoirs Using Gamma-Ray Spectrometry, Western Desert, Utah

Petroleum exploration in the Utah's Western Desert has had limited success, but the potential for new discoveries continues to fuel wildcat drilling. Principal plays include sub-unconformity traps, sub-thrust-fault traps, and traps within valley-fill successions. Fractured Paleozoic carbonates are the main targets among the first two types. Oil and gas shows have been reported from the Confusion Range, but no significant accumulations have been discovered.

Outcrop gamma-ray spectrometry is a powerful tool for correlating stratigraphic sections with well logs. We have initiated a project, GRAPZ (Gamma-Ray Analyses of Paleozoic Strata), to measure sections and construct gamma-ray profiles of strata in the House Range, Confusion Range, and Wah Wah Mountains of western Millard County. Stratigraphic successions, cumulatively about 35,000 ft thick (10.5 km), in these mountain ranges span the Lower Cambrian through Lower Triassic. The conodont biostratigraphy of many of these successions is well known; conodonts are recoverable from core and cuttings. Integration of stratigraphic sections and biostratigraphy with outcrop gamma-ray profiles will assist explorationists by providing better structural and stratigraphic control in existing wells. Our collection of outcrop gamma-ray profiles are from Upper Cambrian and Lower to Middle Ordovician rocks, including the Wah Wah Summit Formation; Candland Shale, Johns Wash Limestone, Corset Spring Shale, Steamboat Pass Shale, and Sneakover Limestone, members of the Orr Formation; Red Tops and Lava Dam members of the Notch Peak Formation; House Limestone; lowermost Fillmore Formation; Wah Wah Limestone; Juab Limestone; and the lower part of the Kanosh Shale.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado