Abstract
In 2010, the anti-vibration stabilizer was introduced as part of the drill string assembly to replace the traditional near bit stabilizer in Algeria. The tool acts like a stabilizer and centralizer while not generating the point loaded blade friction associated with traditional stabilizers. With 100% borehole contact, this tool has improved hole quality and reduced drilling vibrations in many applications.
There are three important vibrational phenomena that can affect drilling performance. Torsional relaxation oscillations induced by non-linear frictional torques between the drill-bit at the rock surface result in the phenomina known as torsional stick-slip. Axial vibrations induce the drill-bit to intermittently lose contact with the rock surface, which is known as bit-bounce. Lateral vibrations are the most destructive mode of vibration and create large shocks downhole by causing the Bottom Hole Assembly (BHA) components to impact the wellbore wall.
The anti-vibration sub is a tool designed to ensure efficient drilling by mitigating lateral vibrations as part of the required energy management. The effectiveness of the sub has been proven through the analysis of downhole data and Mechanical Specific Energy (MSE) comparisons. The anti-vibration sub enables a very high signal-to-noise ratio for MWD (Measurement While Drilling) tools, improves bit performance and borehole quality, reduces the cost per meter for drilling and the non-productive time required for conditioning the hole prior to setting casing. An analysis of the data and field results clearly demonstrates the value of this tool. The anti-vibration stabilizer has been successfully utilized in several applications and is currently standard equipment for most vertical well rotary BHAs in Algeria.
