A Systematic Approach to Performance Drilling in Hard Rock Environments

Summary Since backward whirl was discovered as a severe cause of polycrystalline diamond compact (PDC) bit failure, the oil and gas industry has made great strides toward creating whirl-resistant bits and operating practices. But is whirl still the major cause of PDC bit damage in conventional rotary applications? This paper reports on a recent field study in which downhole vibrations were measured by use of a newly available in-bit vibration-monitoring device. The focus of this study was to understand the primary source of bit damage. In addition, four wells were also drilled by use of a research drilling rig in Oklahoma. In these tests, the PDC bits, bottomhole assemblies (BHAs), and operating parameters were varied to document their effect on downhole vibrations. In these four wells, vibration measurements from the new in-bit measuring device were validated against a commercially available and industry-proven measurement-while-drilling (MWD) vibration-monitoring service. The results of this study indicate that the most common field vibration in hard-rock vertical conventional rotary drilling is stick/slip, not whirl. In field tests, stick/slip was observed almost exclusively. For typical field applications with a surface rotary speed of approximately 70 rpm, the team measured a peak downhole rpm as high as 500 during the slip phase. Stick/slip was identified as the primary cause of bit damage in these applications. Lateral vibration occurring during the slip phase correlated well with the observed damage and is proposed as a new mode of damage during stick/slip. The characterization of the lateral vibrations coupled with stick/slip is presented on the basis of downhole measurements.

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Drilling Performance Improvement in the Haynesville Shale Play

Billa

Mota

Schneider

et al. 2011

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Significant drilling performance improvement was achieved over a two year period in the HPHT Haynesville Shale Play in North Louisiana. Technical challenges include drilling through abrasive, high compressive strength formations, bottom hole temperatures exceeding 360°F, sour gas and shut-in surface pressures near 10,000 psi. The wells are horizontal with 12,500 to 14,500 ft TVD, and 16,500 to 18,500 ft MD. The application and optimization of managed pressure drilling (MPD), underbalanced drilling (UBD), hard rock drilling, casing drilling, casing design and installation procedures will be discussed.

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A Systematic Approach to Performance Drilling in Hard Rock Environments

Cited by 14 publications

References 33 publications

Basics of Drill String Design

Basics of Drill String Design

Downhole Measurement and Monitoring Lead to an Enhanced Understanding of Drilling Vibrations and Polycrystalline Diamond Compact Bit Damage

Drilling Performance Improvement in the Haynesville Shale Play

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