Hammer Motor Smashes Its Way to Speedy Success in Brazil

Abstract

Percussive air hammer tools have been used for many years to increase drilling ROP (rate of penentration) in air drilling applications. Similar developments for mud hammer tools have not been as successful. The incompressible nature of drilling mud makes the percussive action much slower to actuate using the same design methodology, rendering the tool ineffective. Other developments have suffered from reliability issues which have limited their drilling hours, therefore making them economically unfeasible. A novel percussive mechanically-actuated Hammer Motor, suitable for either mud or air drilling applications, has changed the landscape. This unique hammer assembly is assembled into a standard mud motor, without affecting the bit to bend distance. The percussive action of the tool is designed such that the bit remains in contact with the formation, while the hammering takes place against the top of the drive mandrel, driving the bit into the formation. The percussive impacts serve to greatly increase the effectiveness of the roller cone bit in crushing the rock, thus significantly increasing ROP. This paper illustrates a case study from Brazil, where the Operator has been using turbine motors or conventional motors to drill vertical wells through hard rock formations. The Hammer Motor displayed significantly higher ROP than the benchmark established by the other motors, while also reducing bit costs. These improvements in drilling performance improve the economics of drilling these hard rock formations, and are also applicable to other drilling applications.

Vibro-impact model and validation of the axial dynamics of a vibration-assisted drilling tool

“…Therefore, the equation of motion that describes the dynamics of the third degree-of-freedom is given in Eq. (5).…”

“…In a technological perspective, the development of a drilling system that combines the rotary motion (scratching) with a percussive action (indenting) is not a new concept in the oil well industry. Such concept can be seen in the Andergauge Hammer [17], the SDS Digger fluid hammer [12,23], the BBJ fluid hammer [22] and the NOV fluid hammer [5,8,9,18]. Preliminary field test results with these vibrationassisted drilling tools (VAD) have shown a significant improvement in the rate of penetration (ROP) when drilling hard-rock formations.…”