Research on Weight-on-bit Self-adjusting Dual-diameter PDC Bit Design and Effect Evaluation Utilizing Stress-Releasing Effect of Rock at Bottomhole

Rock-breaking efficiency is not so satisfied using the conventional PDC bit, especially in the hard, soft–hard interbedded, and strong abrasive formations in ultra-deep wells. A method is proposed to make full use of stress-releasing effect at bottomhole, thereby improving the rock-breaking efficiency, and a supporting weight-on-bit (WOB) self-adjusting dual-diameter PDC bit (WSDB) has been invented. The WSDB can dynamically adjust the depth-of-cut control characteristics, which could improve the rate of penetration (ROP) while mitigating the stick–slip vibration caused by the rapid change of depth of cut. The stress field of the rock at the bottomhole is calculated with a numerical method, and the working mechanism of the bit is analyzed. The application effect of the WSDB is evaluated through laboratory tests preliminarily. The results show that the stress concentration area on the shoulder of the reaming bit is decreased obviously and a larger stress unloading area emerges in the intersection between reaming and pilot bit. Thus, mechanical specific energy (MSE) can be greatly reduced when the reaming bit drills into this section. Indoor tests show that the maximum ROP of WSDB can be reached up to 70% higher compared to the conventional PDC bit, and higher ROP could be obtained with a relatively lower bit torque. With drilling parameters greater than the critical revolution and WOB, the reduction in MSE can be reached up to 36% during the rock-breaking process. Making further efforts into the optimization of bit structure to reduce the vibration intensity is expected to achieve more improved bit performance.

[1]  N. Mancktelow.  Fundamentals of Rock Mechanics, 4th Edition, John Conrad Jaeger, Neville G. W. Cook, Robert Zimmerman, Wiley-Blackwell, May 2007, 488 pages, Hardcover, ISBN: 978-0-632-05759-7, US $88.00 , 2009 .

[2]  L. W. Ledgerwood,et al.  Mitigating Drilling Dysfunctions and Enhancing Performance with Self-Adjusting Bit Technology: Analytical and Experimental Case Studies , 2017 .

[3]  D. Gumich,et al.  Unique Approach to Bit Design Coupled with Innovative Rolling PDC Cutter Sets New Performance Benchmark Drilling Extremely Abrasive Sandstone Formations, Usinsk Region Russia , 2017 .

[4]  Zhenhua Rui,et al.  Molecular Dynamics-Based Simulation on Chemical Flooding Produced Emulsion Formation and Stabilization: A Critical Review , 2020, Arabian Journal for Science and Engineering.

[5]  Bao-yin He,et al.  Quantitative modeling of suspended sediment in middle Changjiang River from modis , 2006 .

[6]  Fred E. Dupriest,et al.  Maximizing ROP With Real-Time Analysis of Digital Data and MSE , 2005 .

[7]  Yezid Ignacio Arevalo,et al.  Quantification of Drillstring-Integrity-Failure Risk Using Real-Time Vibration Measurements , 2012 .

[8]  Lin Shi,et al.  Technologies in deep and ultra-deep well drilling: Present status, challenges and future trend in the 13th Five-Year Plan period (2016–2020) , 2017 .

[9]  Alexis Garcia,et al.  Novel Drill Bit Materials Technology Fusion Delivers Performance Step Change in Hard and Difficult Formations , 2013 .

[10]  T. M. Warren,et al.  Bottomhole stress factors affecting drilling rate at depth , 1985 .

[11]  Liu Can-de,et al.  QUANTITATIVE MODELING OF SUSPENDED SEDIMENT IN MIDDLE CHANGJIANG RIVER FROM MODIS , 2006 .

[12]  Seyed Ali Heydarshahy,et al.  Influences of bit profiles on possible fracture modes , 2017 .

[13]  Jun Lu,et al.  Role of Alkali Type in Chemical Loss and ASP-Flooding Enhanced Oil Recovery in Sandstone Formations , 2020, SPE Reservoir Evaluation & Engineering.

[14]  Gensheng Li,et al.  Experiment on rock breaking with supercritical carbon dioxide jet , 2015 .

[15]  H. Van Heekeren,et al.  Conical Diamond Element Bit Sets New Performance Benchmarks Drilling Hard and Abrasive Formations, Offshore Netherlands , 2015 .

[16]  R. Teale.  The concept of specific energy in rock drilling , 1965 .

[17]  Malcolm Taylor,et al.  Pointing Towards Improved PDC Bit Performance: Innovative Conical Shaped Polycrystalline Diamond Element Achieves Higher ROP and Total Footage , 2013 .

[18]  Chen Chen,et al.  Innovative Rolling PDC Cutter Increases Drilling Efficiency Improving Bit Performance in Challenging Applications , 2013 .

[19]  T. M. Warren,et al.  Laboratory drilling performance of PDC bits , 1988 .

[20]  T. M. Warren,et al.  Experimental Evaluations of Drill Bit and Drill String Dynamics , 1994 .

[21]  Jinliang Huang,et al.  Shale gas in China: Characteristics, challenges and prospects (II) , 2015 .

[22]  Wei Zhang,et al.  Equipment and technique for improving penetration rate by the transformation of drill string vibration to hydraulic pulsating jet , 2014 .

[23]  Hussain Rabia.  Specific Energy as a Criterion for Bit Selection , 1985 .

[24]  Carlos Carrion,et al.  Advanced Drilling and Logging Technologies Give New Life to Aging Fields in Ecuador by Enabling Reentry Drilling , 2015 .

[25]  Smith Bits,et al.  Conical Diamond Element Bit Sets New Performance Benchmarks Drilling Extremely Hard Carbonate/Chert Formations, Perm Region Russia , 2015 .

[26]  Yingxin Yang,et al.  Experimental study on the rock-breaking mechanism of disc-like hybrid bit , 2018 .

[27]  Jalal A. Al-Sudani,et al.  Real-time monitoring of mechanical specific energy and bit wear using control engineering systems , 2017 .

[28]  Waleed Agawani,et al.  Multiple Deployments of Hybrid Drill Bits with Optimized Drilling Systems Prove Enhanced Efficiency in North Kuwait Development Wells , 2017 .

[29]  Alexey Ruzhnikov,et al.  Drill Bit Evolution During Execution of Long-Term Offshore ERD Project (Russian) , 2016 .