Valeura Energy Inc. drilled two appraisal wells at Wassana oil field in license G10/48 in Pattani basin, Gulf of Thailand. The results show that additional production wells are viable within the reservoir which could extend the field’s economic life.
The two appraisal wells are on the flanks of the field and were designed to test for suspected additional oil accumulations in the field’s Tertiary clastic section. Both wells targeted the deeper portions of the reservoir section (2.0 and 2.1 sands) which holds most of the remaining underdeveloped oil reservoirs in the field.
The appraisal program was designed to penetrate the oil-water contact in this section to access additional potential down-dip oil volumes. Recently reprocessed 3D seismic data also suggests an upside in a thickening of the reservoir section in the targeted locations. Both wells were successful in fulfilling these objectives.
The first well, A28, was drilled in the main producing fault block of the field, downdip of existing production wells. It encountered 72 ft of net oil pay. While previous reserves estimates were based on a demonstrated oil-down-to depth of 5,517 ft true vertical depth sub-sea (TVDSS), the new well has confirmed the presence of oil down to at least 5,594 ft TVDSS, exceeding the company’s expectations for the vertical extent of the oil column. In addition, the well encountered a thicker package of reservoir sands and new oil-filled sands that have not been previously developed.
The second well, A28-ST1, was drilled to confirm the presence of oil in an untested area south of the main producing part of the field. The well encountered 75 ft of net oil pay proving the presence of oil in this undeveloped area.
Valeura is currently re-mapping the field to integrate the new data and anticipates that the results will yield an increase in its volumetric estimates. Preliminary analysis indicates that about 20 additional production well targets are now potentially viable within the reservoir section appraised by these two wells. Considering this upside potential, Valeura started the concept selection phase of a project to expand the development of the field which will involve deploying additional wellhead and oil processing structures to be used as a higher-capacity production hub than is currently available through the existing mobile production infrastructure.
The drill rig has since mobilized to Jasmine oil field where it is commencing a four well drilling program comprising two production wells and two appraisal wells to support additional production drilling in 2024. After the program at Jasmine, the rig is scheduled return to the Nong Yao oil field for a five well infill drilling campaign.
In July 2023, Valeura suspended production operations at Wassana field to review safety and operating practices of the field’s third-party-owned and operated floating storage and offloading vessel (FSO). As a result of this review, Valeura and the FSO’s third-party owner have opted to select a new sub-contractor to operate the FSO going forward. Valeura intends to implement a phased transition plan with production resuming in fourth-quarter 2023.
Wassana oil field is a collection of crude oil-bearing sandstone reservoir intervals of Miocene age. The field is estimated to contain 2P reserves of 6.1 million bbl of oil as of Dec. 31, 2022.
Valeura holds 100% operated interest in license G10/48.