Concurrent 5. Presentation for: Pluto 4D Monitor Two – a second outstanding success
Sandra Mann A *A Woodside Energy Ltd, 11 Mount Street, Perth, WA 6000, Australia.
The APPEA Journal 62 - https://doi.org/10.1071/AJ21312
Published: 3 June 2022
Abstract
Presented on Tuesday 17 May: Session 5
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.
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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. |
