What Offshore CCS Will Look Like in the Gulf of Mexico - Perspectives from Texas

Abstract

Since 2009, the Gulf Coast Carbon Center at the Bureau of Economic Geology (The University of Texas at Austin) has undertaken multiple integrated geologic and geophysical studies to evaluate the continental shelf in the Gulf of Mexico for CO2 storage. Funding for these studies has come primarily from the U.S. Department of Energy (NETL), but also from the State of Texas General Land Office, which administers the State offshore resources. A recent award-winning publication (BEG Report of Investigations No. 283) compiles the diverse topics explored during this long history of characterization: Geological CO2 Sequestration Atlas for Miocene Strata Offshore Texas State Waters. This is the first attempt to comprehensively address CO2 storage topics for the near offshore in the Gulf Coast. Topics addressed in the volume include Miocene stratigraphy and depositional systems with regional cross sections, implications of petroleum systems for CO2 storage, microscopic and stratigraphic evaluation of anticipated primary seals, regional static capacity estimates, and field-scale examples of storage reservoirs (including modelling and simulation). Detailed stratigraphic and structural interpretation of hundreds of wells and faults using integrated 3D seismic data is now continuous over an area greater than 5,000 square kilometres (2,000 square miles). In three localities a total of 137 square kilometres (53 square miles) of novel high-resolution 3D seismic data has been acquired to understand technological capabilities for imaging the overburden above injection reservoirs, and to address characterization, risk reduction, and monitoring needs. General conclusions from this work are that the inner shelf of the Gulf of Mexico presents superb geology for CCS with ample storage capacity. Sources and developing pipeline infrastructure are well located for development of offshore storage hubs. The thick and relatively young and porous clastic Miocene stratigraphy has multiple regional confining intervals deposited during regional sea level transgressions. Static CO2 storage capacity estimates beneath the Texas State waters between Mexico and Louisiana total more than 30 Gt, including both depleted hydrocarbon reservoirs and saline intervals. More regional assessments identify approximately 125 Gt of storage. This offshore geologic CO2 storage resource is regionally and nationally significant, is available for both CO2 sequestration and enhanced oil recovery (EOR), and is likely to be the most appropriate region for giga-tonne scale storage in the United States.