Influence of fracturing reconstruction of coalbed methane wells on gas production and development suggestions in Guizhou Province: taking Panguan syncline as an example

In Guizhou Province, there are many coal-bearing structural units, many layers of coal, thin thickness, and most of them are low permeability reservoirs, so it is advisable to adopt the process of “staged fracturing and combined layer drainage and production” to develop coalbed methane. Taking Banguan syncline coalbed methane well as an example, this study analyzed the fracturing effect of two vertical Wells on the basis of the scale of fracturing reconstruction, and then studied the influence of fracturing reconstruction effect on the gas and water production of coalbed methane Wells, and finally summarized the reasonable threshold of efficient fracturing construction parameters of Banguan syncline coalbed methane Wells. The results show that hydraulic fracturing is an effective way to increase permeability of low permeability reservoir, and the permeability increase multiple is closely related to the scale of fracturing reconstruction. The differences of sand addition, liquid addition and single-hole displacement per meter of coal seam between the two Wells of Banguan syncline lead to the permeability ratio of 55∶1 after fracturing reconstruction, and the permeability difference after reconstruction is large. Increasing the liquid addition, sand addition and single hole displacement per meter of coal seam is beneficial to improving the transformation effect of coal seam and gas production. It is recommended that the liquid addition per meter of coal seam should not be less than 400 m³, the sand addition per meter of coal seam should not be less than 20 m³, the fracturing construction displacement should not be less than 8 m³/min, and the single hole displacement should be controlled above 0.2 m³/min. According to the permeability of the coal seam after fracturing and reconstruction, it can be appropriate to quickly discharge and depressurize the coalbed methane Wells with good reconstruction effect. Otherwise, the intensity of discharge and production should be controlled to reduce the sensitivity damage of the reservoir caused by fast discharge and depressurization. The research results can provide technical reference for the permeability and energy improvement of low permeability coal seam in this block.