BHA and Drillstring Modeling Maximizes Drilling Performance in Lateral Wellsof Barnett Shale Gas Field of N. Texas

摘要

The Barnett Shale field of North Texas is one of the mostprolific and fastest growing natural gas fields in North Americawith a multi-trillion cubic feet equivalent upside potential.However, the area presents numerous drilling challenges. In thevertical section, roller cone bits had unacceptable lowpenetration rates while PDC bits suffered premature damage.High torque and drag along with low penetration rates hampereddrilling the curve and lateral sections. To address thesechallenges, a detailed engineering analysis was performedutilizing sophisticated BHA and drill string modeling software.Engineers studied offset wells and drillstring modeling includingbuckling load analysis, critical speed analysis, and torque anddrag analysis.As a result of the study, engineers determined that bit whirl andstick-slip were resulting in premature bit damage and reducedROP while drillstring buckling resulted in inefficient transfer ofweight on bit. Modeling helped design a BHA that mitigatedbuckling while optimized drilling parameters avoided criticalspeeds. The improvements resulted in 42% to 121% higherpenetration rates with minimal damage to the PDC bits. The 8-3/4" vertical section was drilled in one PDC run in 60 out of 104wells resulting in significant reduction in rotating hours andaverage cost per foot. The new BHA reduced drillstringbuckling and significantly reduced torque and drag whiledrilling the curve and lateral sections.The authors will describe the significance of applying principlesof buckling load and torque and drag analysis; to designtechnically sound BHA's. They will also discuss how to utilizedrillstring dynamics to avoid critical speeds.