Turbodrill BHA Solves Build Section Challenges, Anadarko Basin

Abstract

Drilling the difficult build section in the Granite Wash play in Washita County, Oklahoma can present a number of challenges. The formation contains multiple reservoirs within complex sequences of sandstone, siltstone and shale interbedded with granite/limestone wash. This hard and abrasive matrix is uniquely challenging and unpredictable which makes conventional drilling with positive displacement motors (PDM) combined with rollercone TCIs and/or PDC bits difficult due to the lack of desired durability. The operator required a new technological solution to minimize the flat time in this particular section by reducing bit trips and/or improving penetration rates (ROP). In normal situations, a turbodrill paired with a diamond impregnated bit is a viable option to tackle this challenge. However, the conventional steerable turbodrill BHA was incapable of achieving the target build rates required by the customer in their deviated section. The challenges in the build section of the well were evaluated by the engineering team. A review of the run data and use of mathematical-based predictive analysis software identified the changes needed to achieve the required doglegs needed to meet the challenge. The study indicated that using a steerable turbodrill with two bends and a specific stabilization setup coupled with a diamond impregnated bit with a shorter gauge length could yield up to 65% higher build rates. This new turbodrill BHA has been successfully field trialed in numerous wells in Washita County, Oklahoma and surrounding areas and has achieved the goal of consistently building a curve with a plan of 14°/100ft and has set numerous new field performance records. Drilling time has been consistently reduced by 45% (from 8.0 to 4.3 days) and bit runs reduced from 2.5 to 1.0 while achieving 40% higher ROP. The authors will present case histories that illustrate performance achievements in the build sections and provide details that contributed to the success of this unique BHA.