Importance

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Abstract

This invention relates to oil well production, particularly to a method and apparatus for downhole stimulation of oil production from a well by generating cyclic shock waves in and around the wellbore. High pressure air passes through gas supply conduit (16), downwardly through pilot passage (54) of pilot valve (48) into internal piston valve chamber (58) and high pressure chamber (30). When the pressure in chambers (58) and (30) exceed 80% of the line pressure from supply conduit (16), pilot valve (48) shifts vertically, exposing the upper end of piston valve (56) to high pressure, and thereby urging the piston valve downwardly to open the high pressure chambers (58) and (30) into the low pressure chamber (32), thus creating an abrupt charge of gas into the well. The movement of line pressure through high pressure passage (78) to a position behind the annular shoulder (82) of the piston valve (56) causes the piston valve to return to its start position, and the differential pressure across pilot valve (48) causes it to move back to its start position.

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First Claim