ABSTRACT

A basin characterization and play analysis were conducted over the Miocene and Pliocene section of the Veracruz Basin to assess remaining gas potential. The comprehensive data set included information from 144 wells, more than 5600 miles (9,000 km) of 2-D seismic, and more than 200 mi² (500 km²) of 3-D seismic. In addition, production-engineering, well-test, and geochemical data were analyzed and synthesized into the basin evaluation.

Reservoir, trap, source, migration pathways, and timing play elements were individually characterized, mapped, and integrated into a framework of play types and play fairways. Reservoirs are dominated by channelized to fan-dominated siliciclastic turbidites. Long-lived compressional and strike-slip forces created abundant four-way and three-way closures. Valid stratigraphic traps are present and currently produce gas. Gas chimneys, geopressure, and locally intense structuring contribute to top-seal uncertainties. Source rocks are considered adequate for gas across the study area. Biogenic gas prevails in many upper Miocene and lower Pliocene reservoirs, eliminating the need for deep-seated, fault-induced migration pathways. Surface seeps and gas shows are common.

Thirty-two plays were evaluated on the basis of a combination of stratigraphic age, depositional facies, and trap type. Play areas were defined according to reservoir limits of either channel-dominated or fan-dominated facies. Trap density and postulated trap areas for each play were determined by a detailed mapping of existing reservoirs, anomalies, and closures within two calibration areas. Future trap numbers and sizes for each play were based on the ratio of the calibration area to the play area as a whole. Using of this method, we attempt to extrapolate play-characteristic geology from an area of high data quality and quantity to areas of lower confidence.