--> --> The Mancos Shale in the Albuquerque Basin: an oil play limited by structure and thermal maturation

AAPG Rocky Mountain Section Meeting

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The Mancos Shale in the Albuquerque Basin: an oil play limited by structure and thermal maturation

Abstract

The Mancos Shale (Upper Cretaceous) has exploratory interest in the nonproductive Albuquerque Basin, a Late Tertiary rift basin formed by dominantly by faults. The Mancos C zone is the primary oil producing unit in the San Juan Basin and is of major interest in the Albuquerque Basin. Evaluation of Mancos C thermal maturity is essential to resource evaluation. The Albuquerque Basin is sparsely drilled with cuttings available only on a few deep wells. To evaluate Mancos C thermal maturity, a published gravity model of Tertiary fill thickness was used to project depth to the Mancos C in undrilled areas. A depth-dependent maturation model based on vitrinite reflectance was developed. Together these two models allowed estimation of thermal maturity throughout the basin. Depth to Mancos C varies widely. The Zianna Uplift in the north bifurcates the basin. A deep arm west of the uplift has higher oil potential with the Mancos C at or near peak oil generation over a 60 mi2 area. To the east of the uplift lies a divide that separates the Albuquerque Basin from the Santo Domingo Basin to the north. The Mancos C on the divide is at peak oil generation and has higher oil potential of a 30 mi2 area. The Mancos C has insufficient thermal maturity on the Zianna Uplift and on uplifted blocks east and west of the Albuquerque Basin. To the south of the Zianna Uplift, the basin is deeper and the Mancos C is within the thermogenic gas window.