However the main diagenetic process in sandstone such as compaction, cementation and dissolution also change these variations and affect the reservoir quality. These changes result in variations in porosity, fluid distribution, and permeability. Depositional conditions at any instant vary from one location to another which results in lateral as well as vertical changes within the reservoir and within individual rock units.

The depositional environments associated with sandstones are very important and they range from terrestrial to deep marine, including: Fluvial ( alluvial fans, river sediments) Deltaic (levees, distributary deposits ,mouth bars and other sediments formed where river meets a lake or sea) Aeolian(wind-blown dune sands formed in coastal and desert environments) Shoreline ( beaches, barrier bars, tidal deltas and similar deposits formed in coastal areas) Glacial(sandy materials in tillites and other glacier deposits) and Deep-sea sediments, including contourite sands formed by ocean-bottom currents, turbidites and submarine fan deposits, formed by gravity-driven mass movements. Arenites are the best known petroleum reservoir rock with good porosity and high permeability mainly dependent on reservoir fluid and rock properties mainly influenced and modified by the depositional environment and burial history diagenetic processes. According to Dott's (1964) classification scheme, sandstones are classified into: quartz arenite, sublithic arenite, lithic arenite, arkosic arenite and arkose based on the mineralogy of framework grains, and arenites, wackes, and mudrocks based on the type of matrix present in between the framework grains. Like sand, sandstone may be any color, but the most common colors are tan, brown, yellow, red, grey, pink, white and black depending on the mineral composition. Sandstone is a clastic sedimentary reservoir rock composed of mainly quartz and/or feldspars, and typically deposited by relatively high-energy processes, which winnow out much of the fine particle size fraction while transporting and depositing the coarser (sand-sized) particles.

Sandstone depositional environment