Possible use of Tractors for Coiled Tubing Drilling
Directional Coiled Tubing Drilling (DCTD) is a highly effective and efficient method of accessing tight and isolated reservoirs. The ability to drill extended laterals with precise depth control means that even relatively impermeable formations may be exposed over sufficient length to be economically productive. The ability to side-track existing wellbores and steer accurately to isolated, undrained targets revealed by 21st century seismic techniques breathes new life into old assets.
But there are limits. The laws of physics set an upper limit on the horizontal reach of coiled tubing, as we discussed here.
One way of overcoming these limits is to use a Tractor. If this conjures up an image of a red machine with black knobbly tyres, think again. A Coiled Tubing Tractor is a BHA component whose job is to engage with the walls of the borehole and push the BHA along, augmenting, and in the extreme, replacing the push provided by the CT.
In the realm of CT drilling, we’re typically talking about borehole sizes less than 5 inches. A market leading manufacturer of CT Tractors has products of this diameter capable of providing an additional 9000 lb of Weight On Bit, which can translate in to several thousand extra feet of hole drilled.
Of course nothing in this world is free. These extra feet will come at a cost of additional deployment length, and additional valuable metal in the hole. The need for careful planning and pre job simulation becomes even more important. A CT tractor makes it possible to get the BHA so far along a lateral that it becomes impossible to retrieve simply by pulling at surface.
Yet in the right place, with the right engineering back up, the coiled tubing tractor, mated to a world class Coiled Tubing Drilling BHA represents a piece of technology whose time has come.
Author: Richard Stevens