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PESA Vic/Tas 2018 Annual General Meeting and April Technical Meeting (Your next dry hole will most likely be caused by seal failure)

Wednesday, April 18 @ 12:00 - 14:00

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Guest Speaker: Mark Smith, Karoon Gas Ltd

Mr. Mark A. Smith (Dip. App. Geol, Bsc. (Geology)) is the Executive Director and Exploration Director of Karoon Gas Limited.

Mark has more than 35 years’ experience as a geologist and exploration manager in petroleum exploration and development in Australia, South East Asia and North and South America. Mark worked with BHP Petroleum for 18 years in a range of positions from well site geologist through to Gippsland Basin Exploration Manager. He then worked as a consultant for ten years specializing in fault-seal analysis. Mark co-founded Karoon Gas Ltd, listing in 2004 which had good success with discoveries in the Browse Basin and Brazil. In 2017 Quantiseal Pty. Ltd. (www.quantiseal.com) was set up to provide fault-seal consulting services with Mark a director and shareholder.

Whilst experienced in all facets of oil and gas exploration, his primary geotechnical interest for the last twenty years has been increasingly in trap integrity and fault seal analysis. Whilst consulting he carried out analysis and research on fault seal calibration and prediction and provided services to major companies (oil and gas and CCS). The fault seal software developed then has been continually refined.

The PESA Vic/Tas Branch April Technical Meeting will be preceded by the 2018 Annual General Meeting, to commence at 12:45pm. We welcome any new nominations for the Vic/Tas Branch Committee (see attached flyer for Meeting Notice and Nomination Form).

 

Abstract

“A survey done by Schlumberger proposes that 45% of industry dry holes are owing to lack of seal. A recent paper by Rudolph and Goulding (2017) supports this describing a lookback study of exploration drilling by Exxon for a ten-year period and finding that 50% of their dry holes were owing to trap failures and this percentage actually increased to 60% of dry holes in mature well understood plays.

Despite this, there is a major mismatch between the importance of seals in hydrocarbon trapping and the sophistication of seal evaluation”. (John Karlo HGS presentation March 2018).

So what is going on?

There is a knowledge problem here.

For the scale of economic field sizes, seismic and well data are now providing sufficient resolution to define the form and boundaries of structures. Core data can provide a measure of the critical reservoir properties. These properties can be calibrated to petrophysical data to reasonably estimate hydrocarbon volume and flow rates and now increasingly with the aid of better seismic, reservoir variations over field or prospect areas can be more reliably mapped.

Contingent seal intervals can be identified and mapped also, however, when it comes to fault seal related leakage the size of a leak can be very small. Hydrocarbon leak positions on fault trap seal surfaces can occur at very localized positions and large hydrocarbon traps can be drained through very small leak zones. A sample calculation from data by Muskat (1949) shows that in a modelled case, a single 1/1,000 in. (0.035mm) open fracture overlying a 500ft (150m) oil column would leak at the rate of 150 million bbl/1,000 yr. (ref; Marlan W. Downey 1984)

As such it is unlikely that fault related critical leak locations (other than structural spills) would be sampled or recognized even with extensive drilling. As such, knowledge level for quantitative fault seal analysis is often very low.

This low knowledge problem has given rise to quite diverse views. “During the 2012 EAGE conference on seals a poll was conducted and on nearly every question sizable minorities disagreed with the majority views. For example, on the question of whether fault gouge acts as a static seal – 59% of respondents said it often did but 27% said it did not. A cynic, with justification, may see the foundations of seal evaluation as so weak that the whole effort is invalid.” (John Karlo HGS presentation March 2018)

There are two main camps, the ‘Gougists’ and the ‘Juxtapositionists’. Who is right and is there a middle ground where there is some truth from both camps?

The Quantiseal journey was born of the frustration of appalling well results. During one period in the Gippsland Basin, a ten well program with a risked reserve sum of 100mmbls had an outcome of 10 million barrels (numbers are rounded). The main problem was seal related.

This presentation firstly examines the different approaches to fault seal analysis considering the latest understanding of faulting processes. There has been an enormous amount of good work published by industry and academia on fault processes to address this problem issue.

The second part of the presentation looks at the Quantiseal process and the results achieved in several case studies. The key objective has been to first calibrate the model to existing faulted multi trap fields on a consistent basis to explain the fill type in each sand and explain the column heights. The level of calibration here provides the confidence level to predict reasonable ranges of prospective resources in nearby targets.

Application of this method has led to good outcomes some ending with successful drilling programs and some by withdrawing from the acreage. Both are good outcomes.

Details

Date:
Wednesday, April 18
Time:
12:00 - 14:00
DOWNLOAD FLYER

Venue

Henry & The Fox
525 Little Collins Street, Melbourne, Victoria 3000 Australia

Organizer

PESA VIC/TAS
Phone:
(03) 8199 0317
Email:
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