Gas recovery method for horizontal butt joint wells with hydraulic scouring, migration, pressure relief and outburst elimination

Abstract

The hydraulic scouring, migration, pressure relief and outburst gas recovery method of horizontal butt joint wells disclosed by the present invention, firstly, vertical wells (8) are drilled, the wells are completed with casing above the coal seam roof, and the wells are completed with open holes below the coal seam roof; the horizontal butt joint wells (3 ) of the deflection section (4) and casing cementing; then, the channel of the horizontal section (5) is drilled by conventional means, docked with the vertical well (8), and the well is completed in the open hole; the screen pipe ( 15) and the continuous swimming pipe (13), the screen pipe (15) has screen holes (14), and the top of the continuous swimming pipe (13) is equipped with a piston head (12); continuously inject large flow and high water head into the vertical well (8) Clean water washes the pulverized coal through the sieve (14) to form a pulverized coal slurry, and moves the plug to perform repeated operations; the pulverized coal slurry is discharged to the ground through the annular part of the horizontal wellbore (3); through the gas, coal and water separation device (7) Separation, coal and gas are collected and stored, and water circulation is used for downhole jetting and flushing. The invention provides a new solution for the pressure relief and outburst elimination of the soft and low-permeability coal seam ground.

Description

technical field [0001] The invention relates to the fields of gas outburst reduction and coal bed gas extraction of soft, low permeability and high outburst coal reservoirs, and is especially suitable for coal seams with good coal powder water solubility and easy flow under pressure. Background technique [0002] Drilling technologies for surface mining of coalbed methane are mainly vertical wells and horizontal wells. Due to various reasons, my country's coalbed methane reservoirs generally show the characteristics of "three lows" of low pressure, low permeability and low gas saturation. This "three low" reservoir conditions make the conventional surface vertical well mining technology gradually insufficient in the development of coalbed methane in my country, and cannot achieve the expected results. The practice of coalbed methane development has proved that horizontal wells can effectively connect the fracture system of coal reservoirs, increase the gas and water conduct...

AI Technical Summary

Problems solved by technology

This "three low" reservoir conditions make the conventional surface vertical well mining technology gradually show its shortcomings in the development of coalbed methane in my country, and cannot achieve the expected results

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