Shock Sub Performance Tests

Shock subs are often used when drilling hard rock to reduce the affect of axial vibrations created by roller cone bits, but their affect on lateral vibrations is not well known, thus a series of downhole experiments were conducted at Amoco's Catoosa Testing Facility to evaluate commonly used shock sub designs. Hard rock was drilled with a roller cone bit and each shock sub was tested at two different locations in the BHA under a wide variety of WOB's and rotary speeds. The performance of the shock subs were measured with two downhole vibration sensors (3 axis accelerations), one below and the other above the shock sub to determine the affect of the shock sub on both axial and lateral vibrations.