Fracturing pump assembly

An improved fracturing pump is provided. The pump is reconfigurable on site. The pump uses a bull gear/pinion drive arrangement that increases reliability and efficiency. Internal components of the pump may be varied to meet the requirements of a specific operation. The reconfiguration gives the user the ability to increase or decrease the horsepower of the pump. A closed loop oil feed system provides constant and reliable lubrication even under heavy loads. The sealing system is enhanced to reduce leaks and thermal stresses. The pump also has an improved frame and chassis to reduce NVH and enhance reliability.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to pumps, and in particular, to an improved fracturing pump assembly.

2. Description of the Prior Art

Drilling and production systems are often employed to access and extract hydrocarbons from subterranean formations. These systems may be located onshore or offshore depending on the location of a desired resource. Further, such systems generally include a wellhead assembly mounted on a well through which the resource is accessed or extracted. These wellhead assemblies may include a wide variety of components, such as various casings, valves, pumps, fluid conduits, and the like, that control drilling or extraction operations.

Drilling and production operations, such as fracking, employ fluids referred to as fracturing or drilling fluids to provide lubrication and cooling of the drill bit, clear away cuttings, and maintain desired hydrostatic pressure during operations. Fracturing can include all types of water-based, oil-based, or synthetic-based drilling fluids. Fracturing pumps can be used to move large quantities of fracturing from surface tanks, down thousands of feet of drill pipe, out of nozzles in the bit, back up the annulus, and back to the tanks. Operations come to a halt if the fracturing pumps fail, and thus, reliability under harsh conditions, using all types of abrasive fluids, is of utmost commercial interest. Also, portability of these pumps is an issue, so having a versatile pump which can meet the needs of virtually any situation would be desirable.

An improved fracturing pump is provided. The pump is reconfigurable on site. The pump uses a bull gear/pinion drive arrangement that increases reliability and efficiency. Internal components of the pump may be varied to meet the requirements of a specific operation. The reconfiguration gives the user the ability to increase or decrease the horsepower of the pump. A closed loop oil feed system provides constant and reliable lubrication even under heavy loads. The sealing system is enhanced to reduce leaks and thermal stresses. The pump also has an improved frame and chassis to reduce NVH and enhance reliability.

SUMMARY OF THE INVENTION

It is a major object of the invention to provide an improved fracturing pump assembly.

It is another object of the invention to provide a fracturing pump assembly with interchangeable parts.

It is another object of the invention to provide a fracturing pump assembly with a variable power output.

It is another object of the invention to provide a fracturing pump assembly with an improved crosshead design.

It is another object of the invention to provide a fracturing pump assembly having a fluid end with a 45 degree valve seat.

It is another object of the invention to provide a fracturing pump assembly having an improved frame which utilizes partition support.

It is another object of the invention to provide a fracturing pump assembly where the pump frame is integrated into the skid chassis.

It is another object of the invention to provide a fracturing pump assembly with a closed loop lubricating system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Generally speaking,FIG. 1illustrates a wellsite system in which the inventive fracturing pump can be employed. The wellsite system ofFIG. 1may be onshore or offshore. In the wellsite system ofFIG. 1, a borehole11may be formed in subsurface formations by rotary drilling using any suitable technique. A drill string12may be suspended within the borehole11and may have a bottom hole assembly100that includes a drill bit105at its lower end. A surface system of the wellsite system ofFIG. 1may include a platform and derrick assembly10positioned over the borehole11, the platform and derrick assembly10including a rotary table16, kelly17, hook18and rotary swivel19. The drill string12may be rotated by the rotary table16, energized by any suitable means, which engages the kelly17at the upper end of the drill string12. The drill string12may be suspended from the hook18, attached to a traveling block (not shown), through the kelly17and the rotary swivel19, which permits rotation of the drill string12relative to the hook18. A top drive system could alternatively be used, which may be a top drive system well known to those of ordinary skill in the art.

In the wellsite system ofFIG. 1, the surface system may also include drilling fluid26(also referred to as fracturing) stored in a pit/tank27at the wellsite. A pump29supported on a skid28may deliver the drilling fluid26to the interior of the drill string12via a port in the swivel19, causing the drilling fluid to flow downwardly through the drill string12as indicated by the directional arrow8. The drilling fluid26may exit the drill string12via ports in a drill bit105, and circulate upwardly through the annulus region between the outside of the drill string12and the wall of the borehole11, as indicated by the directional arrows9. In this manner, the drilling fluid26lubricates the drill bit105and carries formation cuttings up to the surface, as the drilling fluid26is returned to the pit/tank27for recirculation. The drilling fluid26also serves to maintain hydrostatic pressure and prevent well collapse. The drilling fluid26may also be used for telemetry purposes. A bottom hole assembly100of the wellsite system ofFIG. 1may include logging-while-drilling (LWD) modules120and120A and/or measuring-while-drilling (MWD) modules130and130A, a roto-steerable system and motor150, and the drill bit105.

FIG. 2shows a cutaway side view of a prior art fracturing pump, illustrating various components of the power assembly, the portion of the pump that converts rotational energy into reciprocating motion. A pump as shown inFIG. 2could be used as pump29ofFIG. 1, although many other fracturing pumps, including those with designs described below in accordance with certain embodiments of the present technique, could instead be used as pump29. Pinion gears52along a pinion shaft48drive a larger gear referred to as a bull gear42(e.g., a helical gear or a herringbone gear), which rotates on a crankshaft40. Pinion shaft48is turned by a motor (not shown). The crankshaft40turns to cause rotational motion of hubs44disposed on the crankshaft40, each hub44being connected to or integrated with a connecting rod46. By way of the connecting rods46, the rotational motion of the crankshaft40(and hub44connected thereto) is converted into reciprocating motion. The connecting rods46couple to a crosshead54(a crosshead block and crosshead extension as shown may be referred to collectively as the crosshead54herein). The crosshead54moves translationally constrained by guide57. Pony rods60connect the crosshead54to a piston58. In the fluid end of the pump, each piston58reciprocates to move fracturing in and out of valves in the fluid end of the pump29.

Referring now toFIGS. 3-4two embodiments of the pump100,200are shown. It can be appreciated that pump100is a triplex pump and pump200is a quintuplex pump. The two pumps100,200function in the same manner except as otherwise noted. It can be seen that the pump100has a crankshaft102, which drives connecting rods104, which ultimately cause reciprocating action of the pistons106to create pumping action as in the prior art model. The conventional style crankshaft102is mounted on the power end frame with strong bearing housing to support the self aligned, double—row roller bearings on every frame plate to deliver maximum life. In a key aspect of the invention, the crankshaft102is connected to connecting rods vis a bull gear pinion drive arrangement. The bull gears & pinion gear are machined to AGMA10specification from forged high alloy steel and heat treated for Dura-last service life. The gears featuring a helical gear profile, are mounted securely to the crankshaft with high strength bolts.

By increasing the size of key components such as the crossheads116, and crankshaft102the pump100can handle greater loads. A closed loop oil feed system118is part of an optimized lubrication system which reduces friction between crosshead116and crosshead guides117. Low operating lube oil temperatures and high mechanical efficiency increase reliability.

A robust sealing system is provided to improve leak and thermal stresses handling during harsh high temperature Frac operation in the field. As previously stated, the interior components of the pump, including the plunger140, can be interchangeably replaced to increase power output, a key aspect of the invention. Stroke length can be varied between 8 and 11 inches, with corresponding variances in output power. In a preferred embodiment power generation ranges from 1800HP to 2250HP. Also, the pump allows variable high pressure output and high flow rate based on variance of plunger size.

Crosshead116is designed to improve friction issues and reduce wear and noise and integrate with two piece crosshead head as alternative design. A closed loop fluid system to increase stroke component life and improve lubrication is described below

The bull gears and pinion shaft are forged and heat treated, made from alloy steel, with the helix gear machined to AGMA grade10. The teeth surface of the pinion shaft are surface hardened to BHN360. The bearings are preferably premium SKF or equivalent with a minimum life of 30,000 hours at rated load. Crosshead116is made of cast iron and may include an optimized electric lube system. High temperature rubber seals are used throughout to improve sealing and reliability. Adding fluid channels as described and shown inFIG. 5below allows for better lubrication of components, as well as better lubricant distribution, and reduces thermal stress. Finally, a new sealing design using fluid mechanics applications to eliminate leak and increase sealing life.

Referring now toFIG. 4a quintuplex variation of the pump200is shown. The variation of pump200includes a crankshaft202and function to operate plungers204which effect pumping action. The size of plungers204can be varied to allow for variable pumping output as in the prior embodiment100.

Power end frame plates206are designed and built from high strength grade steel alloy yet optimized for light weight.

In a key aspect of the invention, the pump frame and skid are integrated to provide rigidity and reduce deflection of stroke components and increase life cycle and durability.

FIGS. 5 and 6show the closed loop lubrication system140. The purpose of the closed loop oil lubrication system is to provide cooling to the stroke components, increase the life of the stroke components such as the crosshead, connector rod bearing and crankshaft bearing.

Efficient lubrication and reduced contamination will increase durability and life of the stroke components. More efficient lubrication circulation and effective contamination reduction will immediately reduce overheating and reduce failure.

The flow diagram shown inFIG. 5circulates oil or lubricant to stroke components and the crankshaft bearing of the pumps100,200. The oil loop lines circulate from the oil tank with action of the feed pump198. Flow regulation is accomplished with check valves9, relief valve7, and filters5, and6to eliminate contamination. A solenoid (not shown) is to improve and regulate steady pressure to the stroke components as shown in the diagram. Oil re-circulated from the pump100,200is cooled by a heat exchanger201before being re-circulated via tank or reservoir4.