Innovative Drilling System with a Built-in Kick-off Ramp Allows Dependable Curve Building in Granite Wash Formation

Abstract

The Granite Wash formation in Beckham County, Oklahoma and surrounding areas presents a number of unique challenges in drilling the build section from a vertical openhole 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 steerable drilling assembly and drill bits particularly in the build section below 12,000 ft. In most cases, the target build rates are not achieved forcing multiple trips and undesirable cost overruns. To remedy the issue, an innovative drilling system was developed which provides a dependable kick-off ramp and a firm beginning in initiating the build section without having to rely on the drilling BHA's fulcrum point. From the bottom, the drilling system consists of hydraulically set openhole anchor, a whipstock, an impregnated drill bit mechanically attached to the top of the whipstock, a double bend turbodrill section and the rest of the BHA. The procedure includes positioning the drilling system in the hole at kick-off point, orienting the whipstock face with MWD in a desired direction, anchoring the whipstock by hydraulically setting the anchor, disengaging the BHA from the whipstock and commencing drilling operations. All of these steps take place in a single trip downhole. Once the impregnated bit and the turbine assembly pass the whipstock, the sliding and the rotating phase begins to achieve the target build rate. The authors will describe the system's components and the running procedure. They will also discuss system performance, realized benefits to the operator, lesson learned and planned improvements going forward.