Drill string pressure altering apparatus and method

1. An apparatus for creating vibrations in a pipe string, the apparatus being disposed on a surface side of the pipe string, the apparatus comprising:

a fluid pump configured to pump fluid within a first fluid bore, the fluid pump being connected to the pipe string via the first fluid bore;

a hydraulic pump configured to pump fluid within a second fluid bore, wherein the second fluid bore is contiguous with a branch off of the first fluid bore along an axis;

a movable plunger disposed between the first fluid bore and the second fluid bore, and configured to alter a pressure of fluid within the first fluid bore; wherein

a tank for collecting at least a portion of the fluid is connected to the apparatus via an opening in the branch of the first fluid bore; and

the movement of the plunger along the axis is configured to generate vibrations within the pipe string via the first fluid bore by blocking and unblocking the opening in the branch of the first fluid bore, thereby altering the amount of fluid allowed to flow to the tank.

2. The apparatus of claim 1 , wherein

when the pressure from the hydraulic pump increases, the plunger is configured to move towards the fluid pump to block the opening in the branch of the first fluid bore to disallow a portion of the fluid to flow to the tank; and

when the pressure from the hydraulic pump decreases, the plunger is configured to move away from the fluid pump to unblock the opening in the branch of the first fluid bore allow the fluid to flow to the tank.

3. The apparatus of claim 1 , wherein the plunger is sealed within the first fluid bore such that fluid within the first fluid bore does not contact the fluid within the second fluid bore.

4. The apparatus of claim 1 , further comprising a piston connected to the plunger, wherein

fluid pumped by the hydraulic pump applies pressure on the piston to move the plunger in a direction towards the fluid pump or away from the hydraulic pump.

5. The apparatus of claim 4 wherein the piston comprises a hydraulic cylinder.

6. A method for generating vibrations in a pipe string via a pressure altering apparatus positioned at a surface side of the pipe string, the method comprising:

pumping fluid within a first fluid bore via a fluid pump of the pressure altering apparatus, the fluid pump being connected to the pipe string via the first fluid bore;

pumping fluid within a second fluid bore via a hydraulic pump of the pressure altering apparatus, wherein the second fluid bore is contiguous with a branch off of the first fluid bore along an axis; and

altering a pressure within the first fluid bore by moving a plunger disposed between the first fluid bore and the second fluid bore, wherein the movement of the plunger along the axis controls a flow of fluid within the first fluid bore to a tank; and

generating vibrations within the pipe string by controlling the movement of the plunger to block and unblock an opening in the branch of the first fluid bore, wherein the opening leads to the tank.

7. The method of claim 6 , wherein the movement of the plunger is controlled by altering a volume of fluid pumped by the hydraulic pump.

8. The method of claim 6 , further comprising:

moving the plunger towards the fluid pump to block the opening in the branch of the first fluid bore to the tank in order to disallow a portion of the fluid to flow to the tank when a fluid pressure from the hydraulic pump increases; and

moving the plunger away from the fluid pump to unblock the opening in the branch of the first fluid bore to the tank in order to allow the fluid to flow to the tank when a fluid pressure from the hydraulic pump decreases.

9. The method of claim 6 , further comprising:

sealing the plunger within the first fluid bore such that fluid within the first bore does not contact the fluid within the second fluid bore.