Compaction of diagenetically altered mudstones – Part 1: Mechanical and chemical contributions

Abstract

Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details.  The study used well data from Cretaceous formations at Haltenbanken. Overpressure is due to disequilibrium compaction and clay diagenesis. Mechanical compaction continues up to temperatures of at least 130 C. The hypothesis that mudstones only compact chemically above 100 C is falsified.

Experimental mechanical compaction of reconstituted shale and mudstone aggregates: Investigation of petrophysical and acoustic properties of SW Barents Sea cap rock sequences

“…While during shallow and intermediate burial effective stress governs the changes in physical and acoustic properties, cementation of biogenic carbonate or silica (Opal-A to Opal-CT) may also cause lithification at shallow depth levels (Bjørlykke, 2015). At higher temperatures in the deeper part of the basin, chemical compaction begins as a result of clay mineral transformation and precipitation of pore-filling micro-quartz cement (Bjørlykke, 1998;Thyberg and Jahren, 2011;Goulty et al, 2016). The temperature, time, and surface area for growth control the kinetics and the thermodynamics of the chemical compaction (Bjørlykke and Aagaard, 1992).…”

“…Moreover, in the second model, there is no implication about mechanical compaction getting negligible at temperatures above 100°C. Goulty et al (2016) documented evidence of mechanical compaction in response to increased effective stress up to 130°C. Another group of scientists, such as Day-Stirrat et al (2010), while using the first conceptual model, have incorporated the second model by stating that there is the mutual impact of mechanical and chemical compactions at deeper depths.…”

“…Alternative conceptual models for the relative impact of mechanical and chemical compactions on mudstones during burial (modified afterGoulty et al, 2016).…”

Material Exchange and Migration between Pore Fluids and Sandstones during Diagenetic Processes in Rift Basins: A Case Study Based on Analysis of Diagenetic Products in Dongying Sag, Bohai Bay Basin, East China

“…Formation temperatures of Cc2 were within the range of 33.2-58.1 ∘ C, which corresponded to the depth range of 500-1000 m [50]. In this depth range, the porosity of mudstones declined from 60% to 10-20% because of compaction, leading to discharge of a large amount of sedimentary water into sandstones [13,53,[55][56][57][58]. Ca 2+ and CO 3 2−…”

Compaction of diagenetically altered mudstones – Part 2: Implications for pore pressure estimation

“…This article and its companion article, Part 1 (Goulty et al, 2016), are directed towards improved pore pressure estimation using wireline logs in mudstones at the temperatures where clay diagenesis takes place. In Part 1, we show that mechanical and chemical compaction have both continued to take place in Cretaceous mudstones at Haltenbanken, offshore mid-Norway up to temperatures of at least 130 ⁰C.…”