bit stabilizer would determine the extent of the angle build rate. After the appropriate length of pipe after the near bit stabiliser you would place a drill string stabiliser. In short the longer the gap between the near bit and the drill string stabiliser the greater the angle building rate. Care must be taken to not have this section too long as the pipe may sag too much and rub against the borehole wall. This could result in key seating and pipe digging into the borehole wall. Stabilisation / Short Lock This assembly is usually used to maintain borehole angle. This assembly is very rigid allowing little movement of the bit. Such an assembly would mean that the stabilisers are closely packed: a near bit stabiliser within 0–30 feet of the drill bit, and two more spaced 30 and 60 feet beyond it. If a short drill collar is used, then the stabilisers can be even closer together. The shorter the distance between the stabilisers means that the drill collars bend less and the weight on bit (WOB) pushes directly on the bit, hence maintaining the angle. Pendulum assembly A pendulum assembly is used to reduce the angle build rate or reduce well-bore angle. In this assembly there is no near bit assembly. The front portion of the (BHA) is allowed to hang as a result of its own weight. In such a case the first stabiliser is placed 30–45 feet behind the bit. This hanging means that there is a force acting on the low side of the hole, which causes the deviation. In the case of a straight hole then the bit simply continues downward. BHA configurations There are three types of BHA configurations. These configurations addressed are usually concerned with the use or layout of drill collars, heavy weight drill pipe and standard drill pipe. Type 1, standard simple configuration, uses only drill pipe and drill collars. In this instance the drill collars provide the necessary weight on the bit. Type 2 uses heavy weight drill pipe as a transition between the drill collars and the drill pipe. Weight on bit is achieved by the drill collars. Type 3 uses the drill collars to achieve directional control. The heavy weight drill pipe applies the weight on the bit. Such a layout promotes faster rig floor BHA handling. It may also reduce the tendency for differential sticking. In