Realise its been a long time but Ive seen/been asked similar...

  1. 54 Posts.
    Realise its been a long time but Ive seen/been asked similar questions a lot recently

    First and foremost the well needs to be as plumb as possible. Deviation can cause strain on casing which can form a weak point during telescoped screen installation or cementing.

    Casing material should be able to withstand pressures and temperatures encountered at depth. often casing collapse specs are focused on with not enough attention going towards installation. Many bore designs put stronger casing at depth and weaker casing towards the surface to save $$. Problem is that weaker casing has to support the weight from the casing below during installation and this can rupture casing easily. Tensile strength of casing is very different to collapse strength.

    Cementing the annulus is where a lot of collapses happen. The differential pressure between the cement on the outside of the casing and the drilling mud or water on the inside of the casing can rupture casing causing cement to flow into production casing. Pressure grouting cement can often require pressures higher than 400psi to displace pressure head of cement. Hydro needs to make bloody sure that correct strength of casing is installed and that this pressure never gets anywhere near the collapse pressure of the casing.

    with good drilling and communication with drillers offering support/advise along with correct choice of design with plenty of mitigation for pressure differentials, water/oil/gas yields, temperatures - no well should fail.

    Why not use resin? - price.
    failure point is not often seals. the failure point is limitations of equipment and limits of people using it.
    find a good driller with good gear and she'll be right.
 
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