Patent Publication Number: US-2022213890-A1

Title: Fracturing pump assembly

Description:
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. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  generally depicts a wellsite system, in accordance with one or more implementations described herein. 
         FIG. 2  shows a side cutaway view of a prior art pump. 
         FIG. 3  shows a perspective view of the fracturing pump assembly of the invention. 
         FIG. 4  shows a perspective view of a second embodiment of the fracturing pump assembly of the invention. 
         FIG. 5  is a diagram of the closed loop oil feed system of the invention. 
         FIG. 6  is a system flowchart depicting operational aspects of the assembly of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Generally speaking,  FIG. 1  illustrates a wellsite system in which the inventive fracturing pump can be employed. The wellsite system of  FIG. 1  may be onshore or offshore. In the wellsite system of  FIG. 1 , a borehole  11  may be formed in subsurface formations by rotary drilling using any suitable technique. A drill string  12  may be suspended within the borehole  11  and may have a bottom hole assembly  100  that includes a drill bit  105  at its lower end. A surface system of the wellsite system of  FIG. 1  may include a platform and derrick assembly  10  positioned over the borehole  11 , the platform and derrick assembly  10  including a rotary table  16 , kelly  17 , hook  18  and rotary swivel  19 . The drill string  12  may be rotated by the rotary table  16 , energized by any suitable means, which engages the kelly  17  at the upper end of the drill string  12 . The drill string  12  may be suspended from the hook  18 , attached to a traveling block (not shown), through the kelly  17  and the rotary swivel  19 , which permits rotation of the drill string  12  relative to the hook  18 . 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 of  FIG. 1 , the surface system may also include drilling fluid  26  (also referred to as fracturing) stored in a pit/tank  27  at the wellsite. A pump  29  supported on a skid  28  may deliver the drilling fluid  26  to the interior of the drill string  12  via a port in the swivel  19 , causing the drilling fluid to flow downwardly through the drill string  12  as indicated by the directional arrow  8 . The drilling fluid  26  may exit the drill string  12  via ports in a drill bit  105 , and circulate upwardly through the annulus region between the outside of the drill string  12  and the wall of the borehole  11 , as indicated by the directional arrows  9 . In this manner, the drilling fluid  26  lubricates the drill bit  105  and carries formation cuttings up to the surface, as the drilling fluid  26  is returned to the pit/tank  27  for recirculation. The drilling fluid  26  also serves to maintain hydrostatic pressure and prevent well collapse. The drilling fluid  26  may also be used for telemetry purposes. A bottom hole assembly  100  of the wellsite system of  FIG. 1  may include logging-while-drilling (LWD) modules  120  and  120 A and/or measuring-while-drilling (MWD) modules  130  and  130 A, a roto-steerable system and motor  150 , and the drill bit  105 . 
       FIG. 2  shows 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 in  FIG. 2  could be used as pump  29  of  FIG. 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 pump  29 . Pinion gears  52  along a pinion shaft  48  drive a larger gear referred to as a bull gear  42  (e.g., a helical gear or a herringbone gear), which rotates on a crankshaft  40 . Pinion shaft  48  is turned by a motor (not shown). The crankshaft  40  turns to cause rotational motion of hubs  44  disposed on the crankshaft  40 , each hub  44  being connected to or integrated with a connecting rod  46 . By way of the connecting rods  46 , the rotational motion of the crankshaft  40  (and hub  44  connected thereto) is converted into reciprocating motion. The connecting rods  46  couple to a crosshead  54  (a crosshead block and crosshead extension as shown may be referred to collectively as the crosshead  54  herein). The crosshead  54  moves translationally constrained by guide  57 . Pony rods  60  connect the crosshead  54  to a piston  58 . In the fluid end of the pump, each piston  58  reciprocates to move fracturing in and out of valves in the fluid end of the pump  29 . 
     Referring now to  FIGS. 3-4  two embodiments of the pump  100 ,  200  are shown. It can be appreciated that pump  100  is a triplex pump and pump  200  is a quintuplex pump. The two pumps  100 ,  200  function in the same manner except as otherwise noted. It can be seen that the pump  100  has a crankshaft  102 , which drives connecting rods  104 , which ultimately cause reciprocating action of the pistons  106  to create pumping action as in the prior art model. The conventional style crankshaft  102  is 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 crankshaft  102  is connected to connecting rods vis a bull gear pinion drive arrangement. The bull gears &amp; pinion gear are machined to AGMA  10  specification 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 crossheads  116 , and crankshaft  102  the pump  100  can handle greater loads. A closed loop oil feed system  118  is part of an optimized lubrication system which reduces friction between crosshead  116  and crosshead guides  117 . 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 plunger  140 , 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. 
     Crosshead  116  is 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 grade  10 . The teeth surface of the pinion shaft are surface hardened to BHN  360 . The bearings are preferably premium SKF or equivalent with a minimum life of 30,000 hours at rated load. Crosshead  116  is 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 in  FIG. 5  below 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 to  FIG. 4  a quintuplex variation of the pump  200  is shown. The variation of pump  200  includes a crankshaft  202  and function to operate plungers  204  which effect pumping action. The size of plungers  204  can be varied to allow for variable pumping output as in the prior embodiment  100 . 
     Power end frame plates  206  are 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 6  show the closed loop lubrication system  140 . 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 in  FIG. 5  circulates oil or lubricant to stroke components and the crankshaft bearing of the pumps  100 ,  200 . The oil loop lines circulate from the oil tank with action of the feed pump  198 . Flow regulation is accomplished with check valves  9 , relief valve  7 , and filters  5 , and  6  to 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 pump  100 ,  200  is cooled by a heat exchanger  201  before being re-circulated via tank or reservoir  4 . 
     It is to be understood that the present invention is not limited to the sole embodiment described above, but encompasses any and all embodiments within the scope of the following claims: