Valve body for a traveling barrel pump

Details Valve body for a traveling barrel pump Valve body for a traveling barrel pump

2002-07-16

2004-06-29

Yu, Justine R. (Department: 3746)

Pumps

Expansible chamber type

Pump mounted in vertical tubular flow conduit removable as...

C417S460000, C417S453000, C417S456000, C417S459000, C166S105000

Reexamination Certificate

active

06755628

ABSTRACT:

REFERENCE TO PENDING APPLICATIONS
This application is not related to any pending applications.
REFERENCE TO MICROFICHE APPENDIX
This application is not referenced in any microfiche appendix.
1. Field of the Invention
This invention relates in general to subsurface pumps and, more particularly, to an improved pump for producing oil-bearing formations, which minimizes spacing between standing and traveling valve assemblies.
2. Description of Prior Art
A conventional oil well includes a cased well bore with one or more strings of tubing extending downwardly through the casing into the oil or other petroleum fluid contained in the subsurface mineral formation to be produced. The casing is perforated at the level of the production zone to permit fluid flow from the formation into the casing, and the lower end of the tubing string is generally open to provide entry for the fluid in the tubing.
There are basically two types of pumps typically associated with the production of oil bearing formations. Such pumps are defined as tubing pumps, rod pumps and each type of pump has its respective advantages and limitations.
With respect to tubing pumps, a tubing pump provides the largest displacement possible in any size of tubing, typically one quarter inch smaller than the nominal tubing inner diameter (I.D.). Where maximum displacement is needed, the tubing pump is the logical choice.
A tubing pump is the strongest pump made. The heavy wall barrel is connected directly to the bottom of the tubing string with a collar, eliminating the need for a seating assembly on the pump to hold the pump in position. Also, the sucker rod string connects directly to the plunger top cage, eliminating the need for the valve rod required in stationary barrel rod pumps. A disadvantage of the tubing pump is the fact that the tubing string must be pulled in order to replace the pump barrel. This increases the pulling unit time at the well.
The tubing pump is a poor installation in gassy fluid. Because of the length of the standing valve assembly and the puller on the plunger (and frequently the increased bore of an extension nipple) there is a large unswept area at the bottom of the stroke, causing a poor compression ratio. This reduces the effectiveness of the pump valving, and causes low pump efficiency in wells where gas enters the pump suction along with the produced fluid. The increased bore of a tubing pump causes increased load on the rod string and pumping unit. It also increases stroke loss due to rod and tubing stretch. As the pump is set deeper, this stroke loss may actually result in a lower net displacement than would be obtained with the smaller plunger of a rod pump. API RP11L calculations should be made on both the tubing pump and the rod pump to determine the optimum selection.
Rod pumps, however, have several distinguishable structures and each structure has its relative, respective advantage and disadvantage. Discussion now proceeds with respect to the relative merits and disadvantages of each rod pump type.
Stationary Barrel Bottom Anchor Pump
The stationary barrel bottom anchor pump is a pump consideration for deep wells. Like the traveling barrel pump, it has the advantage of having the hydrostatic tubing pressure applied to the outside of the barrel without the disadvantage of the column loading on the plunger bowing the pull tube on the downstroke. A stationary barrel bottom anchor pump is normally recommended for wells with low static fluid level, since the production tubing may be run in with only a short perforated nipple or mud anchor below the seating nipple. Thus, if required, the standing valve of the pump may be less than two feet from the bottom of the well.
The stationary barrel bottom anchor pump is superior to the traveling barrel bottom anchor pump for low fluid level wells as the fluid has only to pass the larger standing valve located immediately above the seating nipple in order to be pumped. The top anchor pump shares this advantage.
The stationary barrel bottom anchor pump is excellent for gassy wells when run in conjunction with a good oil-gas separator or gas anchor. The short rise required for the fluid to pass the standing valve and enter the pump minimizes the tendency to foam and thus reduce efficiency.
The stationary barrel bottom anchor pump is hazardous to run pump in a sandy well as sand can settle tightly in the annulus between the pump and the tubing and stick it tightly in the joint. This type of pump also has the disadvantage on intermittent operation that sand or other foreign material can settle past the barrel rod guide and on top of the pump plunger when the well is shut down, with the possibility of sticking the pump when it is put back on production.
Stationary Barrel Top Anchor Pump
The top anchor pump is recommended in sandy wells where a bottom anchor pump may become sanded in and cause a stripping job. The amount of sand that can settle over the seating ring or top cup is limited to a maximum of about three inches as the fluid discharge from the guide cage keeps it washed free above this point. In this respect, this pump type is superior to the stationary barrel bottom anchor pump as if a travel barrel pump is spaced too high, sand can settle around the pull tube right up to the lowest point reached by the pull plug on the downstroke.
The top anchor pump is specifically recommended in low fluid level gassy or foamy wells where it is particularly advantageous to have the standing valve submerged in the fluid being pumped. A gas anchor should run below the shoe on the tubing.
The outside of the pump barrel of a top anchor pump is at suction pressure, consequently it is more subject to burst or part the barrel tube than a bottom anchor pump. Well depth and the possibility of fluid pound should be carefully considered before running a top anchored pump with a thin wall barrel. If the depth of the well is within the depth recommendations, a top anchor pump is a good general purpose installation.
Irrespective of pump type (either rod or tube) certain criteria must be kept in mind to ensure optimum performance. Those considerations are classified under the sub-categories of pump submergence, gas separation and installations where formation sand can be problematic. The energy to fill a pump during the upstroke must be supplied by the well formation. Therefore, it is essential the pump be installed as low in the well bore as possible to maintain minimum back pressure on the formation. The pump intake should be placed below the perforations or as close above them as possible.
Gas through the pump severely reduces pump efficiency. Where gas interference is a problem a properly designed gas separator should be installed as a part of the subsurface pumping assembly. Various styles are available with each having merits for a particular well condition. It is important to keep the back pressure on the gas at the wellhead at a minimum.
A pump will inherently have problems if sand is allowed to enter. Therefore, it is best to utilize some method of sand control to prevent entrance of sand into the well bore. Gravel packs, screens, and chemical bonding agents are frequently used for this purpose.
Traveling Barrel Bottom Anchor Pump
According to the contemporary art, the movement of the traveling barrel in this pump's structure keeps the fluid in motion and sand washed clear almost down to the seating nipple. This minimizes the possibility of sand settling around the pump and sticking it, causing a “wet” pulling job.
The traveling barrel bottom anchor pump is particularly recommended for wells that are pumped intermittently. Since the ball in the top cage will seat when the well is shut down, sand cannot settle inside of the pump. This is important, as it is possible for even a small quantity of sand settling on top of the plunger of a stationary barrel pump to cause the plunger to stick when the well again starts pumping.
In this pump structure, a sucker rod string connects directly to the top cage which in turn connects to the pump barrel. This top cage is

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