Pluto 4D Monitor Two – a second outstanding success
Sandra Mann A * and Scott Gagen AA Woodside Energy Ltd, 11 Mount Street, Perth, WA 6000, Australia.
The APPEA Journal 62(1) 294-309 https://doi.org/10.1071/AJ21032
Submitted: 10 December 2021 Accepted: 11 January 2022 Published: 13 May 2022
© 2022 The Author(s) (or their employer(s)). Published by CSIRO Publishing on behalf of APPEA.
Abstract
A second 4D seismic monitor survey acquired over the Pluto gas field has been an outstanding success despite three tropical cyclones, the start of a global pandemic, and technical subsurface risks. At the time of the Pluto 4D Monitor Two (M2) survey (December 2019 till February 2020), the Pluto field had been in production for 7 years and 9 months and had produced approximately 2 Tcf of gas. The M2 4D survey was acquired between December 2019 and February 2020 over a 20 × 30 km area, on a 12.5 m square grid. Data was processed by CGG to pre-stack depth migration, took 6 months to deliver, and required considerable collaboration with Woodside geoscientists. Use of modern processing technologies, including least squares migration, full waveform inversion and wave equation based amplitude versus offset inversion facilitated a high quality interpretation. On the 4D difference volumes, hardening responses were interpreted as water ingress. Hardening responses were seen in multiple Triassic reservoirs. A pronounced response was seen in a large Triassic valley within a predominantly mudstone background unit, which showed continued water ingress into the valley, upwards from the gas water contact towards the producing well. This confined hardening response contrasted with unconfined, water flood front responses seen in other reservoirs. Both responses enabled detailed interpretation of geological features and provided useful control points for history matching. Interpreted water ingress also gave additional depth control.
Keywords: 4D reservoir monitoring, baseline, fluvial and marginal marine, monitor, Pluto gas field, pressure, reservoir management, reservoir modelling, saturation, seismic interpretation, water ingress.
Sandra Mann was the development geologist for the Pluto Studies Team working on the high-resolution Pluto 3D and Pluto 4D M2 surveys, and associated reservoir modelling. Within Woodside she is a subject matter advisor in fluvial and marginal marine sedimentology and has worked across a range of Australian and international assets. Sandra completed her PhD in Engineering (Earth Science) in 2016 at the University of Adelaide. She also holds BEng and BSc (Hons) degrees. Prior to joining Woodside, Sandra worked for the University of Adelaide and in consulting. Sandra’s interests include 3D and 4D seismic interpretation, reservoir characterisation and integrated reservoir modelling. |
Scott Gagen was the principal development geophysicist for the Pluto Studies Team responsible for the interpretation of the high-resolution Pluto 3D and Pluto 4D M2 seismic surveys. He graduated from the University of Sydney in 1987 with a BSc (Hons) in Exploration Geophysics. His career spans over three decades including 10 years with Ampolex Ltd, 5 years as Lead Geophysicist with Shell International based in Nigeria and more than 20 years at Woodside, working as a seismic interpreter in exploration and development on the North West Shelf of Australia. Scott’s main interests are 3D and 4D seismic interpretation and visualisation, image processing and seismic inversion studies for reservoir characterisation. He is a member of SEG and EAGE. |
References
Adamson KR, Lang SC, Marshall NG, Seggie RJ, Adamson NJ, Bann KL (2013) In ‘Understanding the Late Triassic Mungaroo and Brigadier Deltas of the Northern Carnarvon Basin, North West Shelf, Australia’. (Eds SJ Moss, M Keep) (West Australian Basins Symposium 2013 Proceedings: Perth, WA)CGG (2020) ‘Pluto 4D PreSDM 2020: final Processing Report.’ (Australian Government)
Foster D (2007) The BP 4D story: Experience over the last 10 years and current trends. Paper presented at the International Petroleum Technology Conference, Dubai, U.A.E., December 2007.
| Crossref |
Gerhardt A, Tilbury L (2018) Watching gas move: Seismic 4D reservoir monitoring of the Pluto gas field, North West Shelf of Australia. Paper presented at 80th EAGE Conference and Exhibition 2018, June 2018. pp.1–5. (European Association of Geoscientists & Engineers)
| Crossref |
Haffinger P, Gisolf A, Doulgeris P (2017) Quantitative seismic reservoir monitoring by using a wave-equation based AVO technology. First EAGE Workshop on Practical Reservoir Monitoring, March 2017. Amsterdam, Netherlands. cp-505-00024. (European Association of Geoscientists & Engineers)
| Crossref |
Jenkins, CC, Maughan, DM, Acton, JH, Duckett, A, Korn, BE, and Teakle, RP (2003). The Jansz Gas Field, Carnarvon Basin, Australia. The APPEA Journal 43, 303–324.
| The Jansz Gas Field, Carnarvon Basin, Australia.Crossref | GoogleScholarGoogle Scholar |
Palmer, N, Theologou, P, Korn, BE, and Munckton, T (2005). The Wheatstone gas discovery: A case study of Tithonian and Late Triassic fluvial reservoirs. The APPEA Journal 45, 333–347.
| The Wheatstone gas discovery: A case study of Tithonian and Late Triassic fluvial reservoirs.Crossref | GoogleScholarGoogle Scholar |
Peterson, B, and Gerhardt, A (2020). Pluto gas field: Successful placement of an infill well based on 4D seismic monitoring. The Leading Edge 39, 464–470.
| Pluto gas field: Successful placement of an infill well based on 4D seismic monitoring.Crossref | GoogleScholarGoogle Scholar |
Sambo, C, Iferobia, C, Babasafari, A, Rezaei, S, and Akanni, O (2020). The Role of Time Lapse (4D) Seismic Technology as Reservoir Monitoring and Surveillance Tool: a Comprehensive Review. Journal of Natural Gas Science and Engineering 80, 103312.
| The Role of Time Lapse (4D) Seismic Technology as Reservoir Monitoring and Surveillance Tool: a Comprehensive Review.Crossref | GoogleScholarGoogle Scholar |
Shearwater (2020) ‘Pluto 4D M2 2020: Acquisition Operations Report.’ (Australian Government)
Tilbury, L, and Gerhardt, A (2018). Pluto 4D – Australia’s first 4D over a gas field is an outstanding success. APPEA Journal 58, 395–411.
| Pluto 4D – Australia’s first 4D over a gas field is an outstanding success.Crossref | GoogleScholarGoogle Scholar |
Tilbury, LA, Clayton, CJ, Conroy, TJ, Philip, G, Boyd, GA, Johnson, GA, Rayfield, MA, Hartanto, L, and Lance, DP (2009). Pluto – A major gas field hidden beneath the continental slope. The APPEA Journal 49, 243–268.
| Pluto – A major gas field hidden beneath the continental slope.Crossref | GoogleScholarGoogle Scholar |
