The Trion deep-water field is proposed to be developed through a floating production unit (FPU).
Oceaneering deployed its deep-water autonomous underwater vehicle (AUV) to conduct geophysical survey for the Trion field. Image courtesy of Oceaneering.
BHP Billiton is the first international operator to drill deep-water wells in Mexico. Image courtesy of Government of Mexico.

Trion is a deep-water oil field planned to be developed on the Mexican side of the Gulf of Mexico. BHP Billiton is the operator with a 60% participating interest, while the remaining 40% is held by Mexico’s state-owned oil company Petroleos Mexicanos (Pemex).

Discovered by Pemex in August 2012, the Trion field is estimated to contain 222 million barrels of oil equivalent (Mboe) with additional exploration drilling in the Trion block expected in 2021.

Early engineering contracts for the Trion field were awarded in the first quarter of 2020 with a final investment decision (FID) expected in 2022.

The first oil from the offshore field expected in 2025 and the total investment for the Trion field development is expected to be approximately €10bn ($11bn).

Trion field development background

Australia-based diversified commodities giant BHP Billiton acquired a 60% interest in the Trion field in Mexico’s first-ever deep-water bid round in 2016.

State-owned Pemex entered into a farm-out agreement with BHP Billiton for the Trion field development in 2017.

BHP successfully drilled the Trion-2DEL appraisal well in 2018 becoming the first international operator to drill a deep-water well in Mexico.  It further sanctioned €220m ($256m) for drilling the second appraisal well and to perform further studies for the field development in 2019. The second appraisal well Trion-3DEL was drilled in the same year.


The Trion deep-water field is located within the Perdido Fold Belt in the western Gulf of Mexico, approximately 30km south of the US-Mexico maritime border and approximately 180km away from the Mexican coastline.

The field lies in a water depth of 2,500m and covers an area of approximately 1,285km2.

The Trion oil field development plan

The Trion field is proposed to be developed through a floating production unit (FPU) anchored in 2.5km-deep waters. The various FPU types considered for the project include a floating, production, storage and offloading (FPSO) vessel, or a semisubmersible production platform (SEMI), or a semisubmersible floating, storage and offloading vessel (FSO).

The Trion FPU will utilise truss support for topsides with a total payload capacity of up to 25,000t. It will be designed to accommodate more than 10 risers.

Enhanced oil recovery techniques such as water injection and high-pressure gas injection will be employed to maintain the reservoir pressure of the field.

Trion FPU pre-FEED contractors

BHP called for expressions of interest from potential engineering, procurement and construction (EPC) contractors for the preliminary front-end engineering and design (pre-FEED) of the Trion (FPU) in August 2019.

Three companies including SBM Offshore, TechnipUSA and McDermott were selected in a competitive tender process to conduct pre-FEED studies for the FPU in March 2020.

McDermott confirmed the pre-FEED contract award for a semisubmersible FPU in the same month. The scope of the contract includes a preliminary analysis of the topsides, hull, risers, and mooring as well as project management, execution planning, and estimation services.

McDermott will be assisted by Houston Offshore Engineering and Wood in the pre-FEED study for the hull and topsides of the FPU respectively.

Other contractors involved

Doris, an engineering and project management company, received a contract to provide engineering services for the subsea umbilicals, risers, and flowlines (SURF), as well as the export pipeline for the project in January 2020.

Oceaneering International carried out a deep-water geophysical survey for the project using an autonomous underwater vehicle (AUV).

Transocean provided drilling service for the project, while the appraisal wells were drilled by drillship Deepwater Invictus.