Schlumberger

Technical Paper: Beyond the Technical Limit: Turbodrilling—A Paradigm Shift to World Class Horizontal Well Construction

Society: SPE
Paper Number: 118809
Presentation Date: 2009
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Abstract

Drilling horizontal gas wells in a mature area of southeastern Oklahoma’s Arkoma Basin recently has become operationally feasible. This was achieved as a result of a systematic approach to identifying the best combinations of technology and operating procedures to reduce flat time as a means of minimizing the well’s overall cost and improving drilling efficiencies. This efficiency initiative was considered an urgent issue because the project was in its infancy, and drilling engineers needed to quickly prove feasibility. Horizontals in one Middle Atokan formation are now clearly feasible but lateral drilling in another Middle Atokan formation produced marginal results and requires additional optimization.

To achieve the efficiency goal, the team outlined the following application objectives:

  • Reduce BHA troubles/problems and PDM failures
  • Reduce the need to trip for bit dulls and roller cone bit drilling hour limitations
  • Eliminate fishing for lost cones
  • Produce a smoother wellbore
  • Eliminate reamer trip for liner run

To meet these objectives, the team discussed alternative drilling system approaches, and the drilling team concluded that the use of turbodrilling and impregnated bit technologies offered the most promising approach. The new higher RPM drilling system was run with outstanding results. Since the initial implementation of the impreg bit/turbodrill, the drilling team has completed the entire lateral with one bit, thereby eliminating up to six trips for replacing bits and/or tool failures. The reduction in tripping is due to using a turbine-powered drive system with substantially longer downhole life compared to a PDM and the impregnated bit’s ability to finish the hole section and still have an intact cutting structure. This solved the bit trip problems resulting from the limited numbers of hours per bit and the lost cone issues with 6-1/8-in TCI bits (30 hrs) and short PDC bit runs due to excessive cutter wear. Additionally, the turbine’s smooth drilling action and resulting vibration reduction have significantly reduced the failure rate of expensive downhole tools. With the new turbodrill/impreg combination, 10-day runs have become the new benchmark, performance that PDMs with PDC bits could rarely achieve.