A hitherto controversial process to generate secondary porosity
in deep burial settings is thermochemical sulfate reduction (TSR).
Water in fine-grained glacial and alluvial materials travels down from the surface to underlying ground water aquifers principally through fractures (termed secondary porosity
) and not by flow between the grains (termed primary porosity).
The primary porosity was reduced mainly by compaction and cementation however, grain fracturing, dissolution of framework grains and authigenic cements have produced secondary porosity
to make the Tredian sandstone a potentially good reservoir rock.
Approximately one-third of clastic rock oil and gas storage space is secondary porosity
formed by mineral dissolution .
Aase, Bjorkum and Nadeau (1996) and Pittman, Larese, and Heald (1992) studied the influence of different types and occurrences of clay on the formation and protection of secondary porosity
. Baker, Uwins, and Mackinnon (1993a, 1993b, 1994) used Environment Scanning Electron Microscope (ESEM) to research the sensitivity of clay minerals.
As is known, porosity is a result of various geological, physical, and chemical processes and is generated during the genesis of the rock as "primary porosity" (clastic sedimentation, organogenesis) and/or during the geological history of the rock as "secondary porosity
" (tectonic processes, chemical processes, dissolution, etc.) (Schon 1996).
Interconnectivity of primary and secondary porosity
and nature of secondary porosity
was also determined and quantified.
It is unexpected that in sandstones high secondary porosity
and high content of carbonate cements superimpose at the same depth.
This is secondary porosity
in rock, which often enhances a rock s overall porosity.
The primary intergranular porosity and late-stage diagenetic dissolution- and dolomitization-induced secondary porosity
added to the reservoir quality of the Lumshiwal Formation.
Therefore, we concluded that most of secondary porosity
formed by meteoric water influx through the sandstones at shallow burials.
Various fractures networks and joints pattern has been observed at different localities reveal high secondary porosity