Longhorn (MC546) - LLOG Offshore

Location

The Longhorn Gas Field is situated in the Gulf of Mexico, specifically in the Mississippi Canyon (MC) Blocks 546 and 502. It is approximately 60 miles offshore the Louisiana coast and around 195 kilometers southeast of New Orleans.

Operators and Ownership

The field is currently operated by LLOG Exploration Offshore, although initially it was operated by Eni with a 75% working interest, and Nexen Petroleum Offshore held the remaining 25% non-operating working interest. It appears that the operator has changed to LLOG Exploration Offshore.

Discovery and Production

The Longhorn field was discovered in July 2006. The first production from the field was announced in November 2009, just three years after its discovery. During its initial years, the field was expected to produce approximately 200 million cubic feet of gas per day from subsea wells.

Reserves and Estimates

Pre-drill resource estimates at the Longhorn Gas Field ranged between 60 and 250 billion cubic feet equivalent of gas. The reserves and exploration resources in the Greater Longhorn Area, which includes the Corral Platform and Longhorn field, are estimated to be over 100 million.

Field Development

The development of the Longhorn Gas Field involved several phases:

• Phase I: Included a subsea well tied to the Corral Platform.
• Phase II: Sanctioned in December 2008, this phase added two more subsea wells tied to the platform. The total investment for Phase II was approximately $112.9 million.

The field was developed at a water depth of around 2,400 feet, with the wells tied back to the Corral Platform, which is located in MC Block 365, about 20 miles northwest of the field in a water depth of 620 feet.

Platform and Infrastructure

The Corral Platform, equipped with a production and compression facility, has a processing capacity of 250 million cubic feet of gas per day and 6,000 barrels of oil per day. The platform is a conventional jacket structure and is designed to handle production from both the Longhorn field and other nearby fields, such as the Appaloosa oil field.

Drilling and Wells

Exploratory drilling began in May 2006 and was completed in August 2006. Appraisal well drilling started in 2006, with three wells drilled. The wells identified around 400 feet of net gas pay in multiple sands. The drilling operations were conducted using rigs such as Diamond Offshore’s Ocean America and Transocean’s Amirante.

Current Status

As of recent updates, the Longhorn MC 503 is a producing conventional gas field operated by LLOG Exploration Offshore. The field continues to be an active part of LLOG's operations in the deepwater Gulf of Mexico.