Trion Oil Field, Gulf of Mexico

Trion is an oil field under development on the Mexican side of the Gulf of Mexico. It is located in a water depth of approximately 8,200ft (2,500m), offshore Mexico.

The field is operated by BHP Billiton with a 60% working interest. Mexican state-owned company PEMEX Exploration & Production Mexico is the non-operating partner holding the remaining interest in the field.

BHP acquired the blocks AE-0092 and AE-0093 containing the Trion field in the first-ever deep-water bid round of Mexico in December 2016. It signed an agreement with PEMEX to execute a minimum work programme for the development of the Trion discovery in Mexico in March 2017.

An Environmental Baseline Study (EBS) of the Trion field was submitted to the regulatory authorities in November 2017.

The final investment decision (FID) for the field development will be taken in 2022. The field is expected to produce first oil in 2025.

Location of Trion oil field

Covering an area of 1,285km², Trion deepwater oil field lies in the Perdido Belt within the Western Gulf of Mexico, approximately 30km south of the US-Mexico maritime border and approximately 180km away from the coast of Mexico.

Perdido is a deepwater region characterised by rugged sea-floor terrain and low-pressure and low-temperature reservoirs. BHP Billiton will provide deepwater technology for the project.

Field discovery

Trion deepwater oil field was discovered by the drilling of the exploration well Trion-1 in August 2012.

Pemex drilled the well to a total depth of 4,500m to discover the P3 reserves of 400 million barrels of light oil. Trion discovery at the Perdido Fold Belt was estimated to have approximately 75 million to 125 million barrels of light oil. Another well, Trion-1DL was also drilled within the Trion area.

The gross recoverable resource of the field is estimated to be 485 million barrels of oil equivalent by Pemex.

Appraisal details of Trion oil field

Trion oil field was appraised by the Trion-2DEL appraisal well in 2018, which demonstrated encouraging results.

BHP approved an investment of $256m for the Trion-3DEL appraisal well in February 2019. Trion-3DEL is being drilled to further delineate and characterise the resource.

Trion-3DEL will confirm the volume and composition of hydrocarbons present in the Trion formation, and also determine the feasibility of Trion field development. The appraisal wells were drilled using Transocean’s Deepwater Invictus, an ultra-deepwater drillship.

Trion oil field development details

Trion oil field will be developed with an in-field floating production unit (FPU), including a floating, production, storage and offloading (FPSO) vessel, a semi-submersible production platform (SEMI) or a SEMI and floating, storage and offloading (FSO) vessel.

The unit will be installed at a water depth of approximately 2,500m in the Western Gulf of Mexico under Mexican jurisdiction. The topsides will weigh 17,000t to 25,000t and will have more than ten risers. The FPU will include water injection for enhanced oil recovery and may also include high-pressure gas injection.

The field will be developed with additional drilling to tap the potential to tie back prospects to the future Trion hub.

Contractors involved

BHP contracted Oceaneering International to perform a deep-water autonomous underwater vehicle (AUV) survey, using the DP-2 Ocean Investigator in June 2019. Oceaneering also provided light geotechnical services.

BHP selected three companies, namely SBM Offshore USA, Technip USA, and McDermott to perform the pre-FEED studies for a semi-submersible FPU for the Trion field in March 2020. McDermott will conduct the engineering activities of the topsides, hull, risers, and mooring of the FPU. The pre-FEED tasks will cover aspects such as configuration, sizing and preliminary analysis. McDermott will collaborate with Houston Offshore Engineering (HOE) and Wood to deliver the pre-FEED works. The technical support for the fabrication work will be provided by McDermott’s Altamira Fabrication Yard.

Doris will provide the engineering services for the subsea, umbilicals, risers and flowlines (SURF) and export pipeline.