2014 Rocky Mountain Section AAPG Annual Meeting

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Using a Fluvial Sequence Stratigraphic Framework in the Coal Bearing Formations of the Raton Basin, CO to Build a Deterministic 3D Model.


The Raton Basin of southern Colorado and northern New Mexico contains Cretaceous coal bearing sediments (Vermejo and Raton Formations) deposited in a foreland basin setting during the final retreat of the Western Interior Seaway. Facies trends show an overall progradational system with short retrogradational periods within the Raton Formation. A fluvial sequence stratigraphic framework developed in these coastal sediments has been used to build a 3D deterministic model using Petrel. This fluvial framework divides the section into two part cycles which include a period characterized by lower rates of accommodation creation, multistoried incised channel-fill type architecture and the development of paleosols and a period characterized by higher rates of accommodation creation, higher percentages of fine-grained sediment accumulation, single-storied aggradational channels and the formation of coal. Coal seams, averaging two feet thick in the Raton Basin, are continuous because of their ability to drape topography during deposition and are well preserved because of their resistance to erosion during the early stages of development. The coal seams are used as the main correlation unit. Correlated coal seams provide boundaries enabling the identification of time equivalent low accommodation channels and the low and high accommodation surfaces. The framework of tops is built in Petrel and used during the model building process in the creation of surfaces, horizons and zones which make up the deterministic model. This work has resulted in an enhanced understanding of this complicated system and the ability to history match individual well production in eclipse simulations, thus improving reserves management.