Investigation of Dynamic Stability of Slim Hole Drilling String Using Catastrophe Theory in the Basement Formation, Offshore Viet Nam

摘要

The Cuu long basin is the largest basin in the continental offshore Viet Nam that has high potential oilrnand gas reserves in offshore Viet Nam. One of the biggest oil fields in the Cuu Long basin is the WhiternTiger at which the basement reservoir has the highest oil and gas potential production. Due to drillingrnseveral wells in the basement have been met many troubles as in high well depth, extremely hard rock ofrnthe granitic basement formation, high vibration, shock on the drilling string during drilling, leading to thernshort time of bit life as an increase in the cost per foot. The aim of this work is to investigate the dynamicrnstability by the use of a tool Swallowtail of the catastrophe theory for drilling string in a slim hole withrnhole size diameter of 6 ½″, 5–1/2″, and 4 ½″ in the addressed basement formation. The result of the studyrnis to select a shock sub and new properties of a bit for keeping long bit life.