Rejuvenating legacy seismic for screening carbon storage sites in the Gulf of Mexico

Rejuvenating legacy seismic for screening carbon storage sites in the Gulf of Mexico

A major challenge in the US Gulf of Mexico is transforming disparate public datasets into a quality-controlled database. CGG has successfully created and used a database for its Storage Play Quality Index (SPQI) carbon storage screening methodology and applied its latest imaging technologies to rejuvenate the legacy seismic data.

The last two years have seen a rapid growth in interest in carbon storage in the US Gulf Coast. Carbon storage operators have been racing to take key acreage positions through Local State Bid Rounds and Shallow Water Gulf of Mexico (GOM) Lease Sales. The associated area of interest stretches across the coastlines of both Texas and Louisiana and contains high-quality reservoirs for carbon storage which occur within the Miocene clastic section at 2,500 ft – 10,000 ft.

Screening – Data and Workflow

To support operators in screening potential carbon storage sites, CGG created a quality-controlled and consistent database of legacy data. Data types include well log suites, deviation surveys, check shot surveys, well test data, core data, biostratigraphy, water chemistry and formation pressure data. The available information was a mix of analogue and digital data, totalling thousands of data files in some wells.

Data science workflows were developed to identify, evaluate, extract and enhance the data into a consistent digital database. Over 600 wells were selected for mapping and approximately 400 wells were used for extracting petrophysical properties.

The process of SPQI mapping incorporates key properties for carbon storage evaluation mappable at play scale, including depth, structure, reservoir and seal properties, water chemistry, injectivity and containment integrity. Figure 1 shows the extent of the database and the screening study.

Stratigraphy is used to identify the key aquifers and build the framework of the geological model. This was developed using biostratigraphic data, including micropaleontological and nannofossil distribution data. Key surfaces were tied to seismic reflection data using time-calibrated well logs. The structural framework was based on over 70,000 km of 2D seismic and approximately 25,000 km2 of 3D seismic.

A total of 16 key properties were extracted from the well data, mapped, and combined to produce a composite SPQI map (Figure 1). This was performed for each play to identify the most prospective geographic areas to investigate further for carbon storage sites.

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