System and method for pumping a particle-laden fluid, such as pressurized fracking fluid

Abstract

A system for delivering pressurized fracking fluid to a well includes a high-pressure pump pumping proppant-free fluid, and a double-piston pressure transfer arrangement for transferring pressure from the proppant-free fluid to a fracking fluid. The pressure transfer arrangement includes first and second cylinder assemblies, each having a piston in sliding engagement within a first hollow cylinder so as to define first and second chambers of the first cylinder and third and fourth chambers of the second cylinder. A piston rod interconnects the pistons. A flow selector alternately directs high-pressure proppant-free fluid to the first chamber and the third chamber so as to act on the pistons, thereby applying pressure to fracking fluid within the second and fourth chambers, respectively, for delivery to the well in alternate power strokes. The faces of the pistons facing the first and third chambers have a smaller effective surface area than the faces towards the second and fourth chambers such that pressure in the fracking fluid remains lower than pressure in the proppant-free fluid.

Description

FIELD AND BACKGROUND OF THE INVENTION[0001]The present invention relates to mining and, in particular, it concerns a system and method for pumping a particle-laden fluid, such as pressurized fracking fluid delivered to a well.[0002]Well completion operations in the oil and gas industry often involve hydraulic fracturing (often referred to as fracking or fracing) to increase the release of oil and gas in rock formations. Hydraulic fracturing involves pumping a fluid (a “frac fluid” or “fracking fluid”) containing a combination of water, chemicals, and proppant (e.g., sand, ceramics) into a well at high pressures. The high pressures of the fluid increase crack size and crack propagation through the rock formation, thereby releasing more oil and gas, while the proppant prevents the cracks from closing once the fluid is depressurized. Fracturing operations use high-pressure pumps to increase the pressure of the fracking fluid. Unfortunately, the proppant in the fracking fluid increases ...

AI Technical Summary

Benefits of technology

The present invention provides a system for delivering pressurized fracking fluid to a well. The system includes a source of proppant-laden fracking fluid, a high-pressure pump, a double-piston pressure transfer arrangement, and a flow selector. The double-piston pressure transfer arrangement includes two cylinders and a piston rod interconnecting the two pistons. The system also includes a bidirectional hydraulic actuator and a hydraulic switch for switching the flow selector between two states. The system can provide alternating power strokes to the well and can be used in fracking operations.

Problems solved by technology

Unfortunately, the proppant in the fracking fluid increases wear and maintenance on the high-pressure pumps.

The proposed systems may however suffer from leakage of proppant-laden fluid into the clean fluid, leading to wear on the pressure-transfer system and contamination of the clean fluid.

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