WATERJETTING: A NEW DRILLING TECHNIQUE IN COALBED METHANE RESERVOIRS

Applications of waterjeting to drill horizontal wells for the purpose of degassing coalbeds prior to mining operations and for creating rock-bolts in coalbeds, have long been established. The closest application of waterjet technology in oil and gas industry has been in the development of jet-assisted drill bits. This dissertation investigates the use of high pressure waterjet technology for drilling horizontal wells in coalbed methane reservoirs.

Horizontal Well technology has been in existence for many years. It has found successful applications in both conventional and unconventional reservoirs. The major difference between the conventional horizontal well technology and the proposed waterjet horizontal well technology is the use of waterjet to drill, as opposed to a bit. Secondly, the components of their drillstrings are different.

This research aims at investigating the use of high pressure waterjet technology as a new and a more cost effective technique to drill horizontal wells in coalbed methane reservoirs. The ability of high pressure hose to replace the conventional metallic drill pipe will be investigated. The use of a nozzle to drill horizontal wells in coalbed methane reservoirs, as opposed to a bit will also be investigated. Optimization of tool (nozzle) for best drilling practices will be a major part of the field trials. The various factors that control the direction of hose and nozzle, during drilling operations, will form part of the investigation. Finally, sensitivity studies will be carried out to determine the significance of all the variables that contribute to the impact forcethe force from jets of water that cuts the rocks (coalbeds).