About this Virtual Instructor Led Training (VILT)

The drill string is the simplest piece of equipment in use on a drilling rig and at the same time, the most critical piece. We use the qualifier ‘basic’ because although 99% of the drill string comprises plain tubes that are just screwed together, the lowest section, just above the bit, can go to extreme loading and is fitted with highly sophisticated electronics packages providing both positional and lithological data as well as a steering system to drive and orient the bit. The principle tasks of the drill string are also deceptively simple. These are to:

1. Convey each drill bit to the bottom of the hole and then to retrieve it when worn,
2. Act as a conduit to convey drilling fluid at high pressure down to the bit and
3. Transmit torque from surface to bit, occasionally in concert with a hydraulic motor to drive this bit.

This 4 half-day Virtual Instructor Led Training (VILT) course will cover in detail what it takes to decide on minimum drill string specifications, which are able to support the loads to which it will be subjected. In addition to the need to use a drill string with minimum strength requirements, we also need to ensure that we can prevent drill string failure. If the failure consists of a small split or leak of any kind, then the time involved may be little more than that required for a roundtrip to change the bit. If the string parts, then the recovery is likely to take a considerable amount of time. In a worst case scenario, the fish in the hole may prove impossible to retrieve, requiring a sidetrack. A less than optimal design of the string will reduce the efficiency of the operation and almost always leads to premature bit wear. This is particularly true when we are unable to measure and control the dynamics of the drill string as a whole and the bottomhole assembly in particular. Axial vibrations, torsional vibrations and lateral vibrations may take place in various degrees of severity. The behaviour of the drill string while operating under torsional vibrations is thought to be of great importance and may result in torsional buckling. This VILT course will also cover the drilling optimization limiters, how to identify them and how to remove them. This is done by understanding the drill string dynamics – by operating under the most favourable conditions and by measuring the dynamics in the vicinity of the bit (or at the bit) in order to make timely adjustments.