Patent ID: 8459351
Filing Date: 2013-06-11
Classification: E21B,G01V

Abstract:
1. An apparatus for producing shock waves in a borehole of a well filled or partially filled by a liquid comprising: a) a tubing string extending downwardly into the borehole of the well filled or partially filled by a liquid; b) an elongated damper cylinder connected to a bottom of the tubing string at an upper end and to a damper chamber at a lower end, and said damper chamber is connected to an upper cylinder, and said elongated cylinder has a different internal diameter than an internal diameter of said upper cylinder; c) a damper plunger movably arranged within said elongated damper cylinder and connected to a pumping unit by means at least one sucker rod and polish rod at an upper end and to an upper plunger, movably arranged within said upper cylinder, at a lower end for creating a constant counterforce inside said damper chamber on an upstroke of the pumping unit as a result of constant flow of fluid from the damper chamber into the borehole of the well or from the borehole of the well into the damper chamber through at least one hole on a side surface of damper chamber thereby providing a hydraulic communication between the damper chamber and the borehole; d) a lower cylinder and said upper cylinder has a smaller internal diameter than said lower cylinder and connected to said lower cylinder via a compression chamber; e) a lower plunger movably arranged within said lower cylinder, and said upper and lower plungers are connected to each other by means of at least one rod for compressing a liquid contained within said compression chamber and discharging the liquid into the borehole of the well when said lower plunger exits out of said lower cylinder on the upstroke of the pumping unit thereby generating a shock wave; and f) said lower plunger has a check valve attached to the upper end of said lower plunger and said check valve consists of a cage, a ball and a seat having a hole for supplying a liquid from the borehole into said lower cylinder and compression chamber via an internal channel inside said lower plunger and said hole inside the seat on a downstroke of said pumping unit, and said hole has a diameter determined by the following formulae: where D 1 is the outside diameter of the lower plunger, D 2 is the outside diameter of the upper plunger, L str is the length of the stroke of the pumping unit, N str is the number of the strokes per minute of the pumping unit, k is the coefficient of hydrodynamic resistance of the seat hole and g is a the gravity of acceleration.