Taper lock bypass plunger

A method for use in a production well, comprising:

• permitting a plunger to descend in a well until the plunger hits a structure proximate to a bottom of the well;
• upon the plunger contacting the structure, driving a valve element into an valve seat wherein the valve seat has an annular sidewall surface disposed at a taper angle relative to a centerline axis of the plunger, wherein the taper angle is between one-tenth of a degree and fifteen degrees, wherein an upper valve face of the valve element wedges into the valve seat mechanically locking the valve element in the valve seat and closing a flow path through the plunger;
• and
• permitting the plunger to ascend in the well until the plunger hits a well head structure mechanically disengaging the valve element from the valve seat and opening the flow path through the plunger.

A bypass plunger for use in a hydrocarbon well, comprising:

• a generally cylindrical body having a fluid flow path extending axially through at least a portion of the cylindrical body along a centerline axis of the cylindrical body;
• a first valve seat formed proximate to a bottom of the fluid flow path, the first valve seat having a annular sidewall surface disposed at a taper angle relative to the centerline axis, wherein the taper angle is between one-tenth of a degree and fifteen degrees and wherein a cross dimension of at an inlet end of the first valve seat is greater than a cross dimension of the fluid flow path;
• a valve cage attached to a bottom end of the cylindrical body;
• a push rod disposed in the valve cage, the push rod movable between an open position spaced from the first valve seat to permit fluid flow through the fluid flow path and a closed position, wherein in the closed position an upper valve face of the push rod is at least partially disposed within and mechanically engaged with the first valve seat to block fluid flow through the fluid flow path.