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Turbidite Sands

  1. 1,200 Posts.
    Well I have done a bit of research and found the following on the subject of Turbidite sand fan channels;

    As the name suggests Turbidite sands have been formed by deposition of materials from Turbid waters with the material in suspension as a result of various possible events including submarine landslides, large storm wave actions on shallow grounds, run-off from silty river mouths etc. The sediments can be carried for long distances in underwater currents and usually travel down any steep underwater terrain to be deposited on near flat ocean bottoms. There the sediments settle out with the coarsest sediments deposited first and the finest sediments last. This forms a well-graded bed of sediments usually high in porosity and permeability! The sands are usually deposited randomly and at the base of underground canyons divide and spread out forming fan-systems.

    An example of a Turbidity Sand Fan-shaped system in the Lower Tertiary Period is the “Forties” field in the North Sea of the UK. Here Turbid Sands from the Highlands Of Scotland where transported by river and down the famous Moray Firth. From here the sand spread out past the shoreline and into fan-shaped spreads carried there by underground turbidity-currents. “Porosities and permeabilities are commonly high and give good production rates..” The Famous “Forties” Giant oilfield (i.e. > 500MB) was discovered in 1970. The field is located in a vast anticline “Trap” with a 111m deep oil column in Paleocene sandstone reservoirs. Initial recoverable reserves was 2-billion-Brls and is a prolific producer i.e. 170MB/year.
    Another examples of Tertiary period Turbidity sand fan-shaped petroleum systems include the San Joaquin Valley in California which was previously occupied by deep ocean.

    All interesting stuff and my feeling is that it will only start getting more interesting as the start targeting these “plays” in more slightly more shallow waters that Chinguetti i.e. Banda in around 300m of water.

    Regards
 
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