Abstract
The well that discovered the Barnett Shale was drilled in 1981. However, due to the complexity of this formation and lack of technology, it was not economically possible to drill this field at the time. It was not until the late 1990's that technology became available which allowed for economically viable drilling to be completed. Since then, the Barnett Shale has exploded and is the second largest producing gas field in the US behind the Panhandle-Hugoton field. As of February 2010, 246 operators were listed as working in the Barnett Shale field with13,740 wells on RRC records with 3,273 permitted wells. With the large number of operators, wells and new challenges in the area, it has become critical to find the best possible methods for drilling economically.
In this paper, an operator's conventional method of directional drilling using a steerable motor is being compared to trials of directional drilling using a rotary steerable system. The area of focus is Johnson County in the Barnett Shale (Fig 1). The operator began drilling in Johnson County in 2003. Until a few years ago, directional drilling was primarily completed using a steerable mud motor with either a fixed or adjustable bent housing and MWD. Rotary steerable tools were first tested in 2007, however, the trials covered in this paper began in 2009. One hundred percent of the wells drilled by the operator are horizontal. The typical well was drilled with a lateral less than 5,000 feet long. As drilling progressed, longer laterals were required. Due to surface location restrictions on a group of wells to be drilled, the laterals reached lengths of 6,000-7,000 feet. These lengths were necessary to drill under an urban area where surface locations were not available to accommodate shorter laterals. Torque and drag analysis was conducted to decide if conventional methods could be used. It was determined that conventional methods could not be used because of the potential for the drill pipe to buckle at the base of the curve and that rotary steerable tools must be used.
