2025 Estimated Oil and Gas Reserves Report Gulf of America OCS Region

This Estimated Oil and Gas Reserves Report (EOGR) Fact Sheet provides an overview of the Bureau of Ocean Energy Management’s (BOEM) estimates of oil and gas reserves on the Gulf of America (GOA) Outer Continental Shelf (OCS) as of December 31, 2023. This Fact Sheet will be followed by a comprehensive EOGR report. The GOA OCS encompasses the submerged seabed, whose mineral rights are governed by Federal jurisdiction (Figure 1). For oil and gas fields that span both State and Federal waters, reserves are estimated exclusively for the Federal portion. These estimates are derived for individual reservoirs through geological, geophysical, and petroleum engineering analyses. In 2020, BOEM transitioned from deterministic to probabilistic reserves estimation. This probabilistic methodology is consistent with the Society of Petroleum Engineers et al. (2022), Petroleum Resources Management System (PRMS) to better account for the uncertainty with reserves estimations. Over the past four years, BOEM has developed probabilistic workflows and methodologies leading to the revisions of 1,336 fields and over 37,000 reservoirs. Utilizing these methodologies, reserves estimates have increased by 1.30 billion barrels of oil equivalent (BBOE) since the EOGR was published in 2021, reaching a total of 7.04 BBOE (Table 1). The total is comprised of 5.77 billion barrels (Bbbl) of oil and 7.15 trillion cubic feet (Tcf) of gas.

Outer Continental Shelf Lands Act (OCSLA) requires the Department of the Interior to conduct ongoing investigations to assess the availability of all oil and gas produced or located on the Outer Continental Shelf (OCS). To meet this requirement, BOEM develops independent estimates of economically recoverable volumes of oil and gas in discovered fields through comprehensive field reserve studies. These estimates are continuously updated to incorporate new information from development and production activities and are published annually in the Estimated Oil and Gas Reserves Report.

Methodology

BOEM utilizes three techniques for estimating reserves: analog, volumetric, and performance. Reserve estimates presented in this Fact Sheet are primarily based on volumetric and performance methods. Volumetric reservoir analysis utilizes a geologic model based on subsurface data interpretation and petrophysical well log analysis to define vertical and lateral boundaries of a hydrocarbon-bearing reservoir to calculate bulk volume. Probabilistic reserves estimates require the development of distributions for reservoir rock and fluid properties and recovery factors. These distributions are sampled utilizing a Monte Carlo simulation to arrive at a range of recoverable volumes. By contrast, the previous deterministic methodology requires only a single, most likely, value for each parameter. Once a reservoir begins producing and a production trend is observed, decline curve analysis along with volumetric techniques are employed to forecast future reservoir performance.

Reporting

Previous EOGRs presented reserves as proved plus probable (2P) deterministic estimates, adhering to the classifications established in the PRMS. Table 2 offers an overview of past EOGRs in five-year increments from 1975, followed by annual increments beginning in 2015. Mean reserves for the 2025 Fact Sheet were derived starting at the reservoir level. Reservoir level estimates account for the full range of uncertainty from P0 (smallest value in the dataset) to P100 (largest value in the dataset). Once finalized, reservoir reserve estimates are aggregated up to the field level to get mean reserve estimates for each field. Mean reserves for each field are then summed to get original reserves (production + reserves) estimates. BOEM then subtracts produced volumes to calculate remaining reserves. The total volume of oil and oil-equivalent gas is referred to as barrel of oil-equivalent (BOE) and is reported in barrels at standard conditions.