Development and Field Use of a High-Frequency Gas-Operated Rotary-Percussion Drilling Tool

Abstract

Abstract A successful air or gas-operated percussion tool has been developed and used in drilling nine wells - one each in New Mexico, Utah and Montana; five in Wyoming; and one in Alberta, Canada. Penetration rates with the percussion tool in these wells have averaged 2.5 times faster than those obtained with rotary gas drilling and approximately 5 times greater than rotary mud drilling. Laboratory and field tests indicate that bit footages with rotary-percussion drilling have averaged 1.3 to 4 times those observed with conventional air rotary. Evaluation of laboratory drilling tests and field results shows that, where air drilling is economical, the percussion tool should be used to further decrease well costs. The additional savings should increase the number of wells in which it is profitable to drill with air instead of with liquid-base drilling fluids. Introduction Holes have been drilled in the earth for centuries by variations in the cable tool or churn drilling method. With this percussive method, a heavy steel bit suspended on a cable is dropped a few feet onto the bottom of the well where the bit's kinetic energy is used to chip and crush the formations. The rotary drilling system, introduced to the oil industry around 1900, drilled faster and cheaper than cable tool drilling for most wells. With the development of roller rock bits, rotary drilling gained widespread use in all areas. In an effort to further speed rotary drilling, air was substituted for liquid as the drilling fluid on an experimental basis on several wells in the early 1950's. Air drilling resulted in faster penetration, greater footage per bit, alleviation of lost circulation problems and lower drilling costs. As a result, at the present time air or gas drilling is a routine procedure in parts of Arkansas, Pennsylvania, West Texas and the San Juan basin. The biggest deterrent to widespread use of air drilling has been the water control problem, but, as solutions to this problem are perfected, the scope of rotary air drilling will undoubtedly grow.