Coalbed methane near-wellbore area chemical block removing method

Abstract

The invention discloses a coalbed methane near-wellbore area chemical block removing method. The method sequentially includes (1) selecting a coalbed methane well which has serious-polluted coal reservoir near-wellbore area, obvious-decreased gas production or no gas production; (2) injecting proper ethanol to the coalbed segment of the coal reservoir near-wellbore area; (3) selecting soaking period and times according to coal rank difference of the coalbed segment, and then discharging the ethanol; (4) testing effect, namely comparing daily gas production and operating cost of the coalbed methane well before and after operation. According to the method, near-wellbore organic pollution and coal dust blocking are removed, coal is extracted, porosity and permeability of the coal reservoir are increased, a crack system of the coal reservoir is allowed to communicate with the wellbore, a blocking problem of the coalbed methane near-wellbore area is solved, economical investment is low, and gas production of the coalbed methane well can be increased.

Description

technical field [0001] The invention belongs to the technical field of safe exploitation of coalbed methane, and in particular relates to a chemical plugging removal method for coalbed methane near wellbore. Background technique [0002] CBM wells go through many processes from the beginning of drilling to drainage and gas production. During drilling, perforation, stimulation measures, drainage and workover operations, due to the entry of mismatched liquid, hydration expansion and migration of clay contained in the coal seam, Factors such as pulverized coal precipitation and proppant backflow caused fracture closure and other factors, resulting in a sharp drop in the permeability near the wellbore, seriously reducing the gas production of CBM wells, and even resulting in no water or gas production. If secondary fracturing or radial hydraulic jetting and other plugging removal measures are implemented, the economic investment will be large, and more serious water-sensitive da...

AI Technical Summary

Problems solved by technology

[0002] CBM wells go through many processes from the beginning of drilling to drainage and gas production. During drilling, perforation, stimulation measures, drainage and workover operations, due to the entry of mismatched liquid, hydration expansion and migration of clay contained in the coal seam, Factors such as coal dust precipitation and proppant backflow caused fracture closure and other factors, resulting in a sharp drop in the permeability near the wellbore, seriously reducing the gas production of coalbed methane wells, and even resulting in no water or gas production

If secondary fracturing reconstruction or radial hydraulic injection and other plugging removal measures are implemented, the economic investment will be large, and more serious water-sensitive damage may be caused