Key technologies for accelerating drilling in deep coalbed methane horizontal wells, Ordos Basin

In view of such challenges as prolonged drilling and completion cycle and higher costs caused by severe lost circulation, low drilling efficiency in deviated and horizontal sections, as well as frequent incidents including pipe sticking in horizontal sections during deep coalbed methane horizontal wells drilling in Ordos Basin, the research on key technologies for drilling acceleration was conducted. This paper focuses on research and application in four key areas: wellbore configuration optimization, lost circulation prevention and control, wellbore-stabilizing drilling fluid technology, and efficient trajectory control in horizontal sections. Optimized wellbore configuration scheme based on slimmed hole size and shallower setting depths of technical casing was developed. A high-performance water-based drilling fluid system featuring as low density lost circulation prevention combined with multi-level plugging was introduced. An under-gauge dual-stabilizer bottom hole assembly (BHA) for horizontal section was proposed. In 2024, application of these key technologies in 32 deep CBM horizontal wells shortened the average drilling cycle to 40 days. This represents a 52.66% reduction compared to the average cycle of 84.5 days for 22 wells drilled in 2023. The research demonstrates that well structure optimization, low-density lost circulation prevention combined with multi-level plugging low-viscosity drilling fluid, and undersized double-stabilizer bottom hole assemblies can significantly enhance drilling speed. This provides reliable technical support for the large-scale and cost-effective development of deep coalbed methane resources.