China's Sichuan Province contains prolific gas fields and offers many drilling challenges due to the complex structural geolo gy. The interbedded and abrasive nature of the lithology results in slow drilling penetration rates. Additionally, risk of cavings and stuck pipe limits use of fully stabilized BHAs.

Conventional roller cone and PDC bit technologies had been tested and were limited by impact damage and abrasive wear. Offset wells required more than 230 days due to short drilling intervals and subsequent tripping time. The goal set by the operator was to complete drilling a well in the XinChang Gas Field in less than 180 days. The target well would reach 4700 m total vertical depth (TVD) and contain a challenging 2500-m long 9 1/2-in. interval. Improving rates of penetration (ROP) and increasing distance drilled would be essential in this section.

To identify the solution, a cross-functional team from the operator and the service company conducted extensive technical reviews. Proprietary software was used to analyze the rock properties, and formation drillability problems were identified. BHA modeling revealed potential system instability issues and provided methods to mitigate vibrations. Review of offset drill bits provided clues to drilling challenges and helped form realistic drilling expectations. The correct solution incorporated both products and service. A revolutionary PDC drill bit containing wear-resistant cutters and an innovative design replaced multiple bits and extended the interval drilled by over 80% in certain sections. More importantly, drilling ROP increased by 60%. Experienced bit run supervisors monitored the drilling process and provided real-time options for improving performance.

This paper will describe the application analysis and review process, the critical PDC bit technology, and the implementation instrumental in achieving the 180-day drilling completion goal set by the operator.

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