Abstract:

The side force induced at drilling bit is one of the key factors to cause inclination to the wellbore. This article is dedicated to study the generation of side force and impact factors in order to accurately monitor and control trajectory of the bit as designed. In the context of this work, two types of the bottom hole assembly (BHA) are investigated which consist of one and two stabilizers respectively. Mechanism of side force generation obeys the principle oflevers, in which, the bit and stabilizers play as a fulcrum, drillstrings function as arms, ie. the distance between fulcrums. As a consequence, the modification of side force is esentially the distribution of stabilizers above the bit and along the bottomhole assemble. The side force produced could be positive, negative or zero correcsponding to the building up, dropping offor holding the inclination angle of the borehole. The study is carried out with theoretical calculations which employ force balance principle applied to static and dynamic environments, the application ofLanmark software and the use of experimental control. Study results enable the author to regionally build experimental coefficients devoted to 3 major reserves ofthe Bach Ho field. Besides, a suitable methodology is also emphasized in this work to optimize the selection ofBHAs, which has the maximum adjustment range S.