Down Hole Data Driven Optimization on Bit, Parameters and BHA Lead to an Outstanding Performance in Deep Gas Drilling

Abstract

Deep gas drilling the early Devonian unconformity in Oman is an extremely challenging hard and abrasive application fraught with a diverse set of PDC drill bit challenges and objectives, particularly in the 8 3/8″ vertical section where between 2 to 4 fixed cutter drill bits can be necessary to reach total depth. Each trip can significantly impact well construction cost and delay production on stream dates. Using high frequency digital data collected at the drill bit and detailed forensic analysis of drill bit photographs a new, physics based, drilling equipment and parameter strategy was developed. The section requires drilling approximately 2,000m of hard and abrasive interbedded Sandstone and Shale formations to around 5,000m vertical depth. Drilling performance is typically limited by severe wear to the PDC cutting structure or motor failure from significant torsional and lateral vibrations. High frequency digital data was captured at the bit in conjunction with output data from an automated photometric dull grading system over several wells to identify dysfunction type. The results were then analyzed by vendor and operator SMEs collaboratively to optimize drilling parameter performance and provide insights into optimal cutter shape and grade selection to further reduce drilling dysfunction. Using downhole high frequency digital readings to understand down hole vibrations and the impact of formation interaction on bit dull has led to changes in the cutting structure and the applied drilling strategy. Different drilling approaches were applied to each formation layer to manage interbedded transitions as well as to increase depth of cut for improved drill bit dynamic stability. Insights were derived from an automated dull grading system assisted in optimizing cutter shape and grade selection in the select parts of the drill bit cutting structure. The photometric analysis also helped refine drilling parameters for a more efficient drilling by increasing axial loading on hard formations that then resulted in increased ROP. Additionally, newly developed high abrasion resistant cutters placed optimally in the drill bit at the highest work locations based on automated dull grading feedback resulted in extended cutter life helping to keep the bit sharp and maintain the high rate of penetration through the various layers reaching final section depth with consistently high rate of penetration. The execution of the new physics-based drilling strategy has resulted in improved bit dull grade conditions which helped reaching the section final depth in one run with reduced downhole dysfunctions. that resulted in a section drilled without trips and with reduced well construction costs. The section is 32% faster than the offsets and was drilled 7 days earlier compared to plan.