The 1st AAPG/EAGE PNG Geosciences Conference, PNG’s Oil and Gas Industry:
Maturing Through Exploration and Production

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P’nyang South 2 Well Results

Abstract

The P’nyang Gas Field is located in the Western Province of PNG, approximately 100 km northwest of the Juha field in PRL3 (APPL 11). The greater P’nyang surface structure is dominated by a series of south-west verging thrust folds located frontal of the large Muller Range uplift. The structure was first described and mapped by White (1973), followed by Lamerson (1988), Thomson (1990) and Decker (1992) as part of a Chevron-operated Joint Venture exploration program. The P’nyang surface structure is divided by a southwards verging backthrust (Mt Uni Thrust) into northern and southern fault blocks. Gas and condensate were discovered in the northern block in 1990 through the drilling of P’nyang-1X followed by the appraisal well P’nyang-2X and its sidetrack #3 in 1991. In 2012 P’nyang South-1 and sidetrack #1 were drilled and proved the presence of gas/condensate in the southern fault block of the P’nyang structure. Following seismic acquisition (2015) and reprocessing (2017) efforts the P’nyang structure was interpreted to extend further east than previously mapped. As the final appraisal well planned for the P’nyang field, the P’nyang South 2 well was designed to test this eastern extent as well as to address some other key uncertainties, prior to volume recertification. P’nyang South 2, located 8km east of P’nyang South 1, spudded in Darai limestone on October 22nd 2017. Difficulties encountered running casing in the shallow hole section across the Darai resulted in the well being plugged back and sidetracked. P’nyang South 2ST1 was kicked off on November 24th, with the well deviation eventually built to 30° in order to get as close to the fold axis of the structure as possible. The gas filled Toro A reservoir was intersected and cored. Drilling continued through the Toro B, Toro C, Digimu and Emuk reservoirs, with a full core cut across the estuarine sandstones of the Toro C. A hydrocarbon-water contact was intersected at the top of the Emuk sand at the same depth as the contact observed in P’nyang South 1. The common contact was later confirmed by pressure testing, which also confirmed the gas in all reservoirs was connected. The reservoir section was fully evaluated with a comprehensive suite of LWD and wireline logs. After the primary objectives had been met, the well was deepened in an attempt to locate the bounding fault that underpins the structure in the southern part of the field. Although the fault was not intersected, the structural information provided by the deepening was key in understanding the shape of the forelimb and the likely location of the bounding fault and fault cutoff’s. The rig was released on the 17th of January 2018. Following successful completion of the well, P’nyang was recertified by independent consultants resulting in very significant increases in both 1C, 2C and 3C gas resource volumes.