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PESA WA May Evening talk: Pluto 4D monitor two – a second outstanding success

Thursday, 26 May, 2022 @ 6:00 pm - 8:15 pm (Australia/Perth time)

Free – $50.00

Guest Speaker(s): Sandra Mann and Scott Gagen

Sandra Mann was the development geologist working on interpretation of the high-resolution Pluto 3D and Pluto 4D M2 surveys, and associated reservoir modelling. At 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 and holds BEng and BSc (Hons) degrees.   Scott Gagen was the principal development geophysicist working on 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.

Pluto 4D monitor two – a second outstanding success

Sandra Mann, Woodside Energy, Australia*
Scott Gagen, Woodside Energy, Australia 


If you’ve ever wanted to keep an eye on exactly where your resources are, this presentation is for you. Hear about how we’re watching gas move using subsurface timelapses on a key Woodside asset. See some great seismic that has helped us learn more about our reservoirs than ever before.


Technical Abstract

A second 4D seismic survey acquired over the Pluto 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 on production for seven years and nine months and had produced approximately 2 Tcf of gas.

The M2 4D survey was acquired between December 2019 and February 2020 over a 20 x 30 km area. A successful second survey proved repeatability of the technique and the use of modern processing technologies including Full Waveform Inversion, Least Squares Migration and Wave Equation Based Amplitude Versus Offset Inversion facilitated high quality interpretation.

On the 4D difference volumes ‘hardening’ responses were interpreted as commencing and continued water ingress. Hardening responses were seen in some Triassic TR20 and TR30 reservoirs. Examples will be shown. A pronounced response was seen in a large Triassic valley within a predominantly mudstone unit, confirming continued water ingress into the valley and upwards from the GWC in the direction of the producing well. This confined hardening response contrasted with more unconfined, water flood front responses seen in some other intervals. Both responses enabled detailed interpretation of geological features and aided in understanding the dynamic behaviour of the field. Interpreted water ingress also provided additional depth control, an example of which will be shown.



Thursday 26th May 6pm (for talk starting at 6.45pm)


PESA Members:                                $25.00 (Members must Log on to the PESA website to see the member prices)

Non-members:                                 $50.00

PESA Students Members:               Free (registration is essential)

Bookings close 12 noon for venue and catering purposes.  

As per government requirements, proof of vaccination will be required to enter the venue.


Thursday, 26 May, 2022
6:00 pm - 8:15 pm
(Australia/Perth time)
Free – $50.00
Event Categories:
  • Venue

    Parmelia HIlton
    14 Mill Street
    Perth, WA 6000 Australia
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