Case History—Application of a New PDC Bit Design in Deep Cretaceous and Jurassic Hard Formations in Southern Mexico

Abstract

Abstract In the Tecominoacan Field in Southeastern Mexico, discovered in October 1980, approximately 107 wells have been drilled to date. One of the biggest challenges of these wells is drilling the production interval, which is comprised of fractured limestones and dolomites interbedded with cherty stringers. Historically, of the different bit types and designs tested in the field, the most successful were insert tricone rock bits (IADC 517-537). Even then, multiple trips and low rates of penetration were common while drilling the 8 ½" and 5 7/8" hole sections. Because of natural depletion of the productive formations, penetrating these target intervals requires underbalance drilling techniques that negatively impact bit performance: less bit life due to seal failure, increased trips and decreased bit reliability. An exhaustive analysis of bit performance in the field, including bit wear comparison, and introduction of new materials led to bit design adjustments based on hard rock drilling concepts. The resulting fixed cutter design, with high density cutters incorporating the latest-generation PDC cutter materials, achieved dramatic performance improvements. Where typical rock bit performance in Tecominoacan Field wells averaged penetration rates of 4m/hr in 8 ½" and 5 7/8" hole sections, the new PDC bit design doubled that performance, delivering immediate benefits in saved time, fewer trips, longer bit life and less bit wear. The paper presents case history performance that demonstrates how this hard rock bit technology could be of benefit in other areas with similar lithology and hole conditions.