Research on CBM drilling and completion technology of complicated strata in Jinjia Mining Area of Guizhou Province

Abstract

Taking coal-bed methane wells in Jinjia Mining Area as an example, the characteristics of coal-measure formation lithology changes and their influence on the quality control of CBM well drilling and completion are summarized, drilling construction parameters are optimized, and the drilling of coal seams is less harmful and more efficient. Engineering practice shows that the coal seams and roof and floor lithologies in the coalbed methane exploration area of Jinjia Mining Area are complex, mainly sandstone, mudstone, sandy mudstone, and argillaceous sandstone. The combined distribution of coal seams and roof and floor can be divided into 5 structural models; the coal-bearing strata of Longtan Formation in exploration area is suitable for drilling with medium-low drilling pressure of 20-30 kN, small displacement of 15-20 L/s, and medium-high speed drilling to avoid excessive drilling pressure caused by excessive well inclination; cement slurry density for cementing construction is not easy to exceed 1.85 g/cm3 to avoid the excessive density of cement slurry from invading the near-well zone and causing reservoir damage.

Keywords

• coalbed methane
• drilling quality
• complex formation
• structural model
• soft and hard interbed
• low-damage drilling