Openhole sidetracking is most commonly applied in three drilling scenarios: 1) to drill a horizontal lateral from the main wellbore in unconventional reservoir exploration 2) to drill lateral in a multilateral well 3) to detour around a stuck fish. In most drilling operations, the risk and the economics associated with openhole sidetracking dictates that all commercially available methods and technologies be evaluated thoroughly to achieve the objective and re-establish normal drilling operations. The evaluation is more challenging in medium to hard formations or in highly deviated wells or a combination of both. Recently, the most requested application for the system has been for exploratory wells drilled in unconventional reservoir plays that are recent developments where little or no offset well data exists. In such fields there is significant risk in drilling a horizontal lateral because reservoir characteristics are not well known. The logical step therefore is to rely on the conventional methodology or on the historical experience of field engineers working the region. Traditionally, the predominant openhole sidetracking methodology started with setting a cement plug followed by a directional BHA once the cement hardens. The success of the plug setting operation depends on formation compressive strength, degree of downhole temperature/pressure, wellbore deviation, cement plug depth, quality of cement and cure time. The consequences of plug failure are extra trip time, a new cement plug, loss of drilling days and reconfiguration of drilling trajectory. A recent R&D effort has identified a new method and associated tools that can be effectively utilized to increase operational reliability in openhole sidetracking and to save costs in terms of time and materials.Single trip retrievable openhole sidetrack system: The system is designed for multilateral wells where access to the main bore is a requirement. The system is equally applicable in situations where cement plugs are ineffective such as in medium to hard formation or in highly deviated holes. No cementing operation is required.Cementing openhole system with anchor: The system is designed for unconventional reservoir exploration where the bottom hole is required to be plugged with cement once the pay zone has been identified and kick-off point for a lateral is confirmed. With the anchor firmly holding the system in place, the operator does not have to wait until the cement is fully cured. The solid ramp encased in the cement is used for sidetracking.Cementing openhole system without anchor. This system is designed for wells where there is a hard bottom available. The cement holds the system firmly at the bottom while a solid ramp encased in the cement is used for sidetracking purpose. The paper discusses mechanical and operational features of above system along with their respective field performances. The paper will also describe challenges faced in field runs, how those were overcome, the lesson learned and potential system modifications.

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.