The formation in Hemphill County, Texas and surrounding areas presents a number of challenges when drilling build section from a vertical pilot hole to form a horizontal lateral in the productive zone. The formation is hard and abrasive and it is difficult to anticipate rock properties downhole from one well to the next. The erratic nature of the formation results in unpredictable performance by the drill bit and steerable drilling assembly particularly in the build section of the curve. In many cases, the target build rates are not achieved forcing unnecessary multiple trips resulting in cost overruns.
To remedy the issue, a single trip drilling system was developed to provide a reliable kick-off setting leading to the designated landing point for the lateral. From the bottom up, the drilling system consists of a hydraulically set anchor, an integral deflector, a TCI rock bit mechanically attached to the top of the deflector, a positive displacement motor and measurement tools. The integral deflector provides a dependable kick-off point and a firm beginning in initiating the build section without having to rely on a cement plug or conventional tools requiring multiple trips. The procedure includes positioning the drilling system in the pilot hole at kick-off point, orienting the deflector face with MWD in a desired direction, installing the deflector by hydraulically setting the anchor, disengaging the BHA from the deflector and commencing drilling operations. All of these steps take place in a single downhole trip. Once the rock bit and the motor assembly pass the deflector, the sliding and rotating phase efficiently achieves the target build rate.
The authors will describe the system components and the running procedure. They will also discuss system performance in the Hemphill County application along with realized benefits to the operator, lessons learned and planned improvements.