RE: Question for MCB55...30 Oct 2019 19:26
feelinlucky,
The weight/composition of mud is adjustable at the surface as it is continuously cycled to lift the cuttings to surface and onto the shakers, the mud engineer controls the chemical composition and weight of the mud going back down the well by adding/reducing various elements as required and according to the need to not only keep the reservoir slightly overbalanced (for safety, otherwise a blow out), but also to cake (not block/cement it) the well bore to minimise losses, etc. Somewhat more complicated than that on a fractured basement I feel sure, but essentially the same. The mud is then progressively diluted or unweighted to provide under balance to allow the oil to flow to surface in a controlled manner when ready for a DST.