Multi-Cylinder Hydraulically-Driven Pump System

Abstract

A hydraulically-driven pumping unit for pumping a working fluid includes a pair of double-acting hydraulic piston-cylinder (HPC) assemblies, each having a central axis, a hydraulic cylinder, a piston, and a rod coupled to the piston for axial movement relative to the first hydraulic cylinder. The pumping unit also includes a hydraulic fluid source and an exhaust path for hydraulic fluid. The two hydraulic cylinders are coupled to the hydraulic fluid source and the exhaust path such that the movements of the two pistons are synchronized. The two HPC assemblies are configured for phase-shifted operation such that when pumping unit is reciprocating the two pistons and rods, the a first pair of the pistons and rods always has a different combination of axial position and direction of travel than does a other pair of the pistons and rods. During phase-shifted operation, at least one of the two rods is moving to extend further beyond the corresponding hydraulic cylinder at all times.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims benefit of U.S. provisional patent application Ser. No. 61 / 984829 filed Apr. 27, 2014, and entitled “Multi-Cylinder Hydraulically-Driven Pump System,” which is hereby incorporated herein by reference in its entirety for all purposes.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT[0002]Not applicable.BACKGROUND[0003]This disclosure relates generally to reciprocating pumps. More particularly, it relates to reciprocating drilling fluid pumps used for drilling wells in the oilfield industry.[0004]When forming an oil or gas well, a bottom hole assembly (BHA), including a drill bit, is coupled to a length of drill pipe to form a drill string. The drill string is then positioned adjacent the earth or inserted downhole, where drilling commences. During drilling, a drilling fluid, or “mud,” is circulated down through the drill string to lubricate and cool the drill bit as well as to provide a vehicle for rem...

AI Technical Summary

Benefits of technology

The patent describes a hydraulically-driven pumping unit for pumps designed to address various shortcomings of prior devices. The unit includes two double-acting hydraulic piston-cylinder assemblies that are synchronized and phase-shifted, allowing the rods to have a different combination of axial position and direction of travel. This ensures that the rods are always extending and retracting periodically, resulting in higher efficiency and more consistent pumping performance. The pumping unit also includes a plurality of pumps for delivering the working fluid and a method for operating the pumps to achieve improved pumping efficiency. Overall, the invention provides a more effective and efficient hydraulically-driven pumping unit for various applications.

Problems solved by technology

While pressurizing and delivering the drilling mud, conventional reciprocating pumps impart unwanted pressure pulsations into the fluid.

These pulsations may disturb the downhole instrumentation and communication devices by degrading the accuracy of measurements taken by the instrumentation and hampering communications between downhole devices and control systems at the surface.

Over time, the pulsations may also cause fatigue damage to the drill string pipe and other downhole components.

The conventional triplex mud pumps are heavy and require a change in the cylinder diameter to make a significant change to the discharge pressure.

For example, to achieve a higher pressure, a smaller diameter liner is used; however, this alteration reduces the flow capacity of the pump.

When, instead, the situation requires a higher flow rate and a higher pressure capacity, the installation of a larger pump may be necessitated, and the size and weight of the power section increases substantially.

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