A Fracturing Method for Medium and High Rank Coalbed Gas Reservoirs

Abstract

The invention discloses a fracturing method for medium and high-rank coalbed methane reservoirs, belonging to the field of coalbed methane exploitation. The method comprises: pumping the front liquid of the modified guar gum system after perforating in the roof of the coal seam to form the first fracture; pumping the first sand-carrying liquid of the modified guar gum system into the first crack to fill the sand into it; pump the second sand-carrying liquid of the guar gum system into the first fracture to make it press through the coal seam, and form the second fracture containing sand in the coal seam; continue to pump the third sand-carrying liquid of the active water system , forming multiple longitudinal and transverse fractures containing sand in the coal seam; replace the residual sand in the wellbore into the formation, stop the pump, shut down the well, and flow back the liquid after the fractures are closed and the guar gum is broken; the wellhead pressure After it is zero, wash the well and perforate the whole section of the coal seam. Through the perforation on the roof of the coal seam and the strong sand-carrying ability of the modified guar gum, long fractures are formed and their direction is controlled, the effect of fracture creation is improved, the development of coal seam cracks is avoided, and a long-distance high conductivity area is formed near the wellbore.

Description

technical field [0001] The invention relates to the field of coal bed gas exploitation, in particular to a fracturing method for middle and high rank coal bed gas reservoirs. Background technique [0002] At present, my country's coalbed methane development is mainly concentrated in the Qinshui Basin and the Ordos Basin. These areas are mainly developed and produced by medium and high-rank coalbed methane. The reservoirs of this type of coalbed methane generally have low porosity, low permeability, and low saturation. features. However, the above-mentioned characteristics of coalbed methane reservoirs lead to low natural production capacity, and fracturing is usually required to achieve economical exploitation. At present, the commonly used fracturing transformation is the active water fracturing process, which expands the gas-water flow channel by forming sand-filled fractures with a certain geometric size and high conductivity in the reservoir, thereby improving the permea...

AI Technical Summary

Problems solved by technology

[0005] On the one hand, the existing technology perforates deeply in the middle of the coal seam, which makes the coal seam itself develop fractures, resulting in large fracturing fluid fluid loss; on the other hand, the active water used in the existing technology has poor sand-carrying ability, which makes its fracture creation ability poor

Both of the above two points make the seam-making distance short, which is not conducive to increasing production.