Exploration and Application of Seismic Geosteerable Drilling Technology for Coalbed Methane Horizontal Wells

This passage discusses the challenges faced in drilling 8# Coalbed methane horizontal wells in XX Block of the eastern edge of the Ordos Basin. The challenges include deep burial depth (>2000 m), thin High-quality coal layer thickness (3 m), and short-distance structural variations. The challenges caused high risk of missing targets and run out of the target layers, as well as difficulties in cementing and completion due to uneven well trajectories. This article proposes three solutions to improve precision drilling: precise geological modeling, optimized trajectory design, and accurate seismic geology Steerable Drilling. (1) Based on reasonable velocity field construction and Time-Depth transformation, a precise directional model is constructed using the layer-by-layer approximation principle with reference to marker layers, improving the accuracy of target spot and avoiding premature or delayed entry into the target; (2) Based on a precise geological model, the dip angle of the strata ahead and the development of sweet spots are clearly defined, enabling optimized trajectory design for horizontal wells; (3) Using “1 + N” dynamic modeling to update the geological model in real-time during the drilling process, and actively guide the drill bit through the horizontal segment smoothly by using multi-information judgment of the drill bit position. The actual drilling of 60 completed horizontal wells in this area show: this approach effectively ensures the smooth trajectory and high-quality drilling rate of the horizontal well in the coal seam, providing a basis for subsequent hydraulic fracturing and increasing single-well production. At the same time, it has certain reference significance for the development of coal seam with similar geological conditions.