Tool and method for abrasive formation of openings in downhole structures

1. An abrasive slurry tool, the tool being attachable to a running string, the tool comprising:

a high-pressure assembly, the assembly including a nozzle assembly and a pump; and

a low-pressure assembly in abrasive fluid communication with the high-pressure assembly, the low-pressure assembly comprising a low pressure holding tank configured to carry recharge abrasive fluid with the tool, the pump segregated from contact with the abrasive fluid.

2. The tool as claimed in claim 1 wherein the high-pressure assembly includes a cylinder and a piston translatable within the cylinder, the piston capable of transmitting pressure to an abrasive fluid in the cylinder.

3. The tool as claimed in claim 1 wherein abrasive fluid within the cylinder is expellable at high pressure through the nozzle assembly.

4. The tool as claimed in claim 3 wherein the nozzle assembly further comprises one or more nozzles.

5. The tool as claimed in claim 1 wherein the nozzle assembly is adjustable for direction of fluid emission and proximity to a target structure to be cut.

6. The tool as claimed in claim 1 wherein the low pressure assembly functions to recharge the high-pressure assembly with abrasive fluid during certain periods of operation of the high-pressure assembly.

7. The tool as claimed in claim 6 wherein the high pressure assembly includes a cylinder and a piston translatable within the cylinder, the piston capable of transmitting pressure to an abrasive fluid in the cylinder the certain periods of operation are those wherein the high pressure assembly piston is not transmitting pressure to the abrasive fluid.

8. The tool as claimed in claim 1 wherein the segregation is by a high-pressure assembly piston.

9. The tool as claimed in claim 1 wherein the pump is a wobble plate type pump.

10. The tool as claimed in claim 1 further comprising an anchoring and rotator component.

11. An abrasive slurry tool, the tool being attachable to a running string, the tool comprising:

a high-pressure assembly, the assembly including a nozzle assembly; and

a low-pressure assembly in abrasive fluid communication with the high-pressure assembly, the low-pressure assembly comprising a low pressure holding tank configured to carry recharge abrasive fluid with the tool and a recharge piston in translatable communication with the holding tank to thereby urge abrasive fluid to the high-pressure assembly.

12. The tool as claimed in claim 1 wherein the pump is driven by a motor.

13. The tool as claimed in claim 12 wherein the motor is a mud motor.

14. The tool as claimed in claim 12 wherein the motor is an electric motor.

15. A method for creating an opening in a downhole structure comprising:

running into a borehole on a string, a tool having a high pressure assembly and a low pressure assembly, the high pressure assembly including a nozzle assembly and a pump, the low pressure assembly in abrasive fluid communication with the high pressure assembly, the low pressure assembly comprising a low pressure holding tank configured to carry recharge abrasive fluid with the tool, the pump segregated from contact with the abrasive fluid;

positioning the tool as a target location;

actuating the tool to emit high pressure abrasive fluid at the target structure; and

abrasively affecting the target structure.

16. The method as claimed in claim 15 further comprising recharging an abrasive fluid supply in the high-pressure assembly from the low-pressure assembly.

17. The method as claimed in claim 16 wherein the recharging is carried out during periods when the high-pressure assembly is not producing high pressure.