Drilling Construction in Complex Formation of High Gas Ultra Thick Coal Measure with Water Gushing

Abstract:

In high gas coal measure and ultra thick water sensitive formation with water gushing in different formations, rational design of borehole structure, selection of equipments, drilling methods, drilling parameters and correct operation are the premise of successful completion of drilling operation. And the correct use of slurry is the key for prevention of hole accidents. By proper application of high density water-based film forming mud, the pressure balance between liquid column and the hole wall can be kept and hydration expansion and dispersion breaking off can also be inhibited by fluid loss control in water sensitive formation to prevent the collapse of hole wall and realize the stabilization. The paper introduces the application of these technical measures in complex formation of high gas ultra thick coal measure with water gushing of Yangzhai coal mine in Guizhou and the application effects.

Key words:ultra thick coal measure; drilling; high gas; water gushing; high density mud