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Technical Paper: Minimizing Risks, Maximizing On-Bottom Drilling Time: Turbodrilling with Impregnated Bits Improves Efficiency and Circumvents Trouble Time, Southern Oklahoma

Society: SPE
Paper Number: 119230
Presentation Date: 2009
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Abstract

Drilling in the Anadarko Basin in southern Oklahoma can present a number of distinctive challenges including fractured formations, conglomerates and other eccentric geologic phenomena. In this unpredictable drilling environment, it is difficult to optimize/refine the bit/tool and BHA selections, resulting in unacceptable or inconsistent drilling performance.

To maximize on-bottom time and cut costs, operator and service-company engineers conducted an in-depth analysis in an attempt to improve section economics. They selected a consistently troublesome application where inconsistencies in the use, performance and dull conditions of bits in close offsets were driving up field development costs. From this group, a specific interval was selected for analysis and the data compared with direct offset runs. In the study, engineers considered bit design/materials, turbodrill and BHA stabilization and drilling parameter optimization. Finally, turbodrill/impreg limitations were considered.

The analysis determined that turbodrilling with impregnated bits was a viable option to create savings and could effectively optimize drilling in applications where:

  • specific lithology/formation tops are difficult to define/predict
  • deviation is caused by hard formations encountered at severe dip angles
  • high probability of bit/tool damage from impact/abrasion
  • excessive fishing/tripping issues
  • hole stability/quality may be compromised by frequent trips
  • roller-cone and fixed cutter bit performance is inconsistent

The new-style turbine/impreg BHA was run with outstanding results. The test interval was successfully drilled, eliminating multiple bit trips and reducing overall days. Cost savings were substantial versus a direct offset well that experienced 38 days of trouble time through the same formations. This trial run gives considerable strength to the hypothesis that impreg/turbine drilling can significantly reduce risk compared to traditional BHAs used in direct offsets. The operator plans to further explore the turbodrill/impreg BHA in the near future.

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