Nong Yao Oil Field, Gulf of Thailand

The Nong Yao oil field is situated in the G11/48 concession in the southern Gulf of Thailand, approximately 165km off the coast of Thailand, in a water depth of about 75m.

The G11/48 development block, including the Nong Yao discovery, is owned by operator Valuera Energy (90%) and Palang Sophon (10%).

The final investment decision for the project was approved by Mubadala Petroleum and Kris Energy (previous partners) in August 2013. Oil production from the Nong Yao A and B fields began in June 2015.

Further, an additional development project began to facilitate the commercialisation of a southern extension of the field, referred to as the Nong Yao C. The first oil from the Nong Yao C production facility is expected in June 2024.

Valuera expects that the Nong Yao extension will lead to a rise in production to 11,000 barrels per day (bbl/d), based on the working interest share, from the current 8,100bbl/d.

Nong Yao oil field discovery and drilling

The Nong Yao field was discovered in 2009 by the Nong Yao-1 exploration well, which was spud by an Emerald Driller jack-up rig. The G11/48 concession covers 6,791km² over the southern margin of the Pattani Basin and the north-west border of the Malay Basin.

A successful appraisal drilling programme comprising five wells, that encountered oil, was concluded in 2010.

The Atwood Orca jack-up rig completed the drilling of the Rojana-A exploration commitment well at the Nong Yao field in June 2014. The water depth at the location of the Rojana-A well is 70.6m. The well was drilled to evaluate a series of heaped Miocene sandstone reservoirs.

Additional drilling campaigns at Nong Yao

In 2023, two drilling campaigns were conducted on the Nong Yao field, one in the second quarter on the Nong Yao B wellhead platform (WHP) and the other in the fourth quarter on Nong Yao A.

Valuera has drilled four wells at the Nong Yao A wellhead processing platform (WPP), comprising three production-oriented development wells and one appraisal well. The development wells have met pre-drill expectations and are now operational.

The appraisal well aimed to define certain reservoir intervals not yet in production, and has surpassed expectations by confirming approximately 50ft of new net oil pay across multiple intervals. The outcome is expected to yield two to four additional development targets, forming the foundation for a forthcoming infill drilling campaign.

Collectively, Valuera completed drilling operations on six wells in total, with a net interest equivalent to 5.4 wells. Among them, five wells were focused on development for production purposes while one served as an appraisal well. Additionally, the company carried out a well workover on the Nong Yao field in 2023.

The Nong Yao-13 well, located in the G11/48 concession, was drilled to a measured depth of 5,399ft and encountered approximately 30ft of fresh oil pay across multiple intervals. The outcome is significant as it validates the presence of oil in this section of the block, a concern previously noted in the Nong Yao D area.

The specific intervals containing the discovery consist of relatively shallow, untapped zones not exploited elsewhere in the concession. The reservoirs are presumed to recur throughout the Nong Yao D area, warranting further investigation through seismic data analysis. The analysis aims to identify potential sites for subsequent exploration and appraisal drilling nearby, to accumulate adequate reserves to support future development endeavours.

Reserves at Nong Yao oil field

The Nong Yao oil field contains 2P gross reserves of 12.4 million barrels, as of December 2023.

Nong Yao field development details

The initial development phase comprised 23 wells targeting the primary reservoirs with a WPP at the Nong Yao A and a minimum facility WHP at the Nong Yao B, interconnected via a leased floating storage and offloading (FSO) vessel.

The construction of the production and processing facilities was completed in February 2015 while installation of the FSO was concluded by mid-2015.

Currently, the Nong Yao oil field features two interconnected fixed platforms, housing a total of 37 wells and a processing facility. Processed oil is stored in the FSO vessel and then transferred to shuttle tankers for international sale.

Nong Yao production comprises light, sweet crude oil, typically fetching prices that closely align with the Brent crude oil benchmark.

Nong Yao field expansion details

The company is set to initiate drilling operations for two infill development wells on the Nong Yao A platform, aimed at enhancing production rates in the immediate future.

The Nong Yao C development drilling programme will comprise up to nine development wells, including six producers and three water injectors, and a mobile offshore production unit (MOPU), TSEVEN Shirley.

The MOPU was refurbished in 2023, and a 3km pipeline was laid to link the current Nong Yao field production infrastructure to the MOPU.

The MOPU has been positioned at the site to serve as the wellhead production platform for the Nong Yao C field. Preparations are in progress for hook-up, commissioning, and the initiation of drilling operations for the Nong Yao C field development.

Alongside the development drilling, the company plans to conduct exploration by drilling one well at the adjacent Nong Yao D prospect.

Contractors involved with the Nong Yao development

Nippon Steel and Sumikin Engineering were responsible for the engineering, procurement, construction, installation and commissioning (EPCIC) activities to provide production and processing facilities.

In March 2014, Omni Offshore Terminals was contracted to supply a floating storage and offloading (FSO) vessel with a storage capacity of 700,000 barrels of oil.

Equatoriale Services was awarded the EPCI contract for a single-point mooring (SPM) catenary anchor leg mooring (CALM) buoy for the Nong Yao field. The soft mooring system with station-keeping capabilities was connected to the FSO vessel.

Atwood Oceanics was awarded a contract to supply a jack-up rig for drilling operations at the field. Atwood Orca is a Pacific Class 400 jack-up rig built by PPL Shipyard.

Airpack Nederland supplied oil-flooded, air-cooled, rotary screw air compressors and heatless regenerating adsorption dryers for the WPP and the WHP.

Valeura will use T7 Global Berhad’s TSEVEN Shirley on a lease for the production from Nong Yao C field.