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PESA WA Technical February lunch talk- Spatial and Stratigraphic Controls on Burial Diagenesis and Reservoir Quality in the Triassic Mungaroo Formation
Thursday, 18 February, 2021 @ 12:00 pm - 2:00 pm (Australia/Perth time)$39.00 – $99.00
Hosted with thanks to our Platinum Sponsors Business Events Perth:
And our Gold Sponsors DUG, Katalyst Data Management and PetroDip
PESA WA invites you to our February technical luncheon on Thursday 18th February
“Spatial and Stratigraphic Controls on Burial Diagenesis and Reservoir Quality in the Triassic Mungaroo Formation”
Presented by Saju Menacherry
The Triassic fluvio-deltaic Mungaroo Formation is the main reservoir in the multi-TCF gas plays offshore Northern Carnarvon Basin, Western Australia. Mungaroo Formation sandstone framework grains are dominated by mono crystalline quartz, with minor polycrystalline quartz, feldspar and lithic fragments, mica, heavy minerals, organic matter and detrital clay. Sandstone classifications are mostly subarkose and quartzarenite with sublitharenite and rare arkose, lithic arkose, feldspathic litharenite and litharenite. Sands are typically fine-to coarse-grained and poorly-to well-sorted. Diagenetic events are responsible for the subsurface modification of the sediments after it was deposited and buried to the present depth. Integrating diagenesis and sequence stratigraphy can provide a better way of predicting reservoir quality.
The composition, grain size and sorting vary laterally and vertically even within a single depofacies, due to the high complexity of the Mungaroo Formation sediments and environment of depositional setting. Reservoir quality data were compiled from sedimentological descriptions, petrographic analytical data sets (i.e., petrography, QXRD, MICP, and SEM) and routine core analysis data from various fields in the basin. A detailed depofacies and lithofacies analysis was performed on the sampled intervals to provide sedimentological context to the petrology data and to evaluate the compositional variation in diagenesis. Within the stages of diagenesis spatially, three different diagenesis styles have been identified which emphasize or de-emphasize different burial stage changes.
Style 1, the kaolinitic style is focussed throughout the basin where Jurassic uplift and erosion are best developed, and is best showcased in Gorgon and West Tryal Rocks. Kaolinisation diminishes to the west and north away from Gorgon as structuring becomes more subtle and erosion less influential. Kaolinitic style is important at deep burial prospects (depths) where it (a) inhibits later quartz cementation (especially >800C) and thereby preserves the intergranular primary porosity, (b) pores within kaolinite become significant at deeper depths because of the commencement of quartz cementation in the primary pores, leaving the kaolin pores open and preserve gas productive porosity, and (c) complete kaolinisation prevents illitisation and thus retains the permeability at higher temperatures (>1200C).
Style 2, the micro-quartz coating style is associated with the shallow Mungaroo Formation under Wheatstone-Iago and Pluto Fields. The reservoir quality is controlled mainly by early formed grain-coating of microcrystalline quartz that precipitated from the dissolution of sponge spicules which significantly inhibits quartz overgrowth precipitation and thus preserves primary (intergranular) porosity.
Style 3, the chlorite coating style, found occasionally under the stratigraphic and sediment provenance-controlled areas of wells like Banambu Deep-1, Vos-1 and Homevale-1. The presence of chlorite coating on quartz grains inhibits quartz overgrowth and preserves the primary porosity even during deep heat flow regime.
The new data derived from the integration of the stratigraphic controls with burial diagenesis and quantitative interpretation techniques can predict the reservoir quality and rock properties (e.g., geochemical, geomechanical, petrophysical) of the Mungaroo Formation sands that directly influence good reservoir presence, lower pre-drill risk allocation, resource estimates and optimised recovery strategies.
Member (Early Bird): $69.00
Concession Member [Retired, Graduate or Hardship] (Early Bird): $59.00
Student Member (Early Bird): $39.00
Member (Non-Early Bird): $79.00.
Early bird pricing ends Monday at 5pm (AWST). All ticket sales close at 5pm Tuesday.