Wells – Brushing – scraping – cutting or punching-type cleaners – On sucker rod
Reexamination Certificate
2002-09-06
2004-10-26
Neuder, William (Department: 3672)
Wells
Brushing, scraping, cutting or punching-type cleaners
On sucker rod
Reexamination Certificate
active
06808019
ABSTRACT:
REFERENCE TO MICROFICHE APPENDIX
This application is not referenced in any microfiche appendix.
FIELD OF THE INVENTION
This invention relates to a guide for use on a sucker rod for purposes of stabilizing a sucker rod as it is reciprocated in tubing and/or for scraping paraffin from the tubing wall.
BACKGROUND OF THE INVENTION
A primary source of energy used in the world today is derived from liquid crude oil that is extracted from subterranean formations. When a well is drilled into an oil-bearing stratum, the pressure within the stratum may be sufficient to force the crude oil to the earth's surface and in such case, no pumping action is required. However, in many areas of the world, the subterranean pressure is insufficient to force crude oil to the earth's surface and therefore it must be pumped from the oil-bearing formation to the earth's surface to be processed and refined. Some oil-bearing formations have sufficient formation pressure to initially force crude oil to the earth's surface when a well is first drilled but after time the formation pressure diminishes to the point that the crude oil can be extracted only by pumping.
Crude oil can be pumped from a subterranean formation to the earth's surface in a number of ways including electrically driven centrifugal down hole pumps, hydraulically actuated down hole pumps and hydraulically actuated jet pumps. However, a most common means of pumping oil from a subterranean formation to the earth's surface is by means of sucker rod actuated pumps.
When the typical oil well is drilled, a casing is installed to prevent cave-in, the casing extending from the earth's surface to the bottom of the well. To convey fluid from the formation to the surface, a string of tubing is typically run inside the casing. When a sucker rod pump is employed, it is anchored within a lower end of the tubing and the pump is reciprocated by means of a string of sucker rods extending from the earth's surface. Sucker rods are typically formed of steel and are installed by means of couplings that are attached between threaded ends of the rods. A typical sucker rod may, for instance, be of about 25 feet in length with a coupling between each length of rod. The sucker rods reciprocate within tubing which typically may be 2-4 inches in internal diameter. Pumped oil wells vary in depth from a few hundred feet to several thousand feet. If an oil well is not perfectly vertical (and very few wells are perfectly vertical) the sucker rods tend to slide against the interior surface of the tubing. Couplings are of larger diameter than the sucker rods. Vertical reciprocation of a sucker rod couplings against the interior surface of tubing is detrimental both to the coupling and to the tubing itself. Over a long period, a coupling can wear to the point it becomes defective causing the sucker rods to separate or a hole can be worn in the tubing causing crude oil production to flow out the hole of the tubing instead of to the earth's surface. Further, in deep wells there may be a tendency for sucker rods to whip against the interior walls of the tubing even if the tubing is substantially vertical. For all of these reasons in some wells it is important to provide stabilizers on the exterior of sucker rods to prevent excess wear of sucker rod couplings and the interior of the tubing.
Another problem encountered in pumping oil wells is paraffin. Most crude oil contains some paraffin, however, in some areas of the world the amount of paraffin in crude oil is significant. The temperature of producing formations is normally sufficiently high in that paraffin remains dissolved in the crude oil—that is, the paraffin remains liquid and can be pumped with the crude oil without any problem. However, as crude oil rises from a producing zone towards the earth's surface, the temperature gradually decreases. If the crude oil has significant paraffin, the temperature of the crude oil may reduce to the point that paraffin starts to congeal—that is, to be transformed from a liquid state to a solid state. As paraffin solidifies, it can adhere to the interior of tubing and ultimately become so thick on the tubing wall as to impair fluid flow to the earth's surface. To combat this it has been a known practice in the petroleum industry for many years to install paraffin scrapers on sucker rods for scraping at intervals equal to or slightly less than the stroke of the pump jack to keep the walls of the tubing from closing in to the point that fluid flow is restricted.
The invention herein is intended to attack not only the problems of sucker rod wear and stabilization but also paraffin removal.
The use of sucker rod guides and/or paraffin scrapers is very well known in the petroleum industry. For background information about the construction and operation of sucker rod guides and paraffin scrapers reference may be had to U.S. Pat. No. 4,995,459 issued to John F. Mabry on Feb. 26, 1991.
For additional information about sucker rod guides and/or paraffin scrapers see the following issued U.S. Patents:
U.S. Pat. No.
Inventor(s)
Title
3,058,524
Tripplehorn
Migratory Paraffin Scraper
3,438,404
Tripplehorn
Method of Mounting Well Equipment
3,537,519
Long
Paraffin Scraper
4,589,483
Sable
Rod Centralizer
4,995,459
Mabry
Rod Guide/Paraffin Scraper
BRIEF SUMMARY OF THE INVENTION
The invention herein is a sucker rod guide for use on a sucker rod that is vertically reciprocated within oil well tubing. The term “sucker rod guide” as used herein, means a device to keep sucker rods centered within oil well tubing and that simultaneously act to scrape or dislodge paraffin from the tubing interior wall. Thus “sucker rod guide” is inclusive of a paraffin scraper. The sucker rod guide of this invention is formed of tough, non-metallic preferably plastic material of a type that withstands elevated temperatures, and severe frictional wear, such as polyphenylene sulphide or nylon.
The sucker rod guide is formed of an elongated tubular body portion that concentrically surrounds the sucker rod. A first and second guide portion integrally extend from the body portion. Each guide portion has a semi-cylindrical guide surface of diameter slightly less than “D”. Each guide portion has one portion with an arc of about 180°. The second guide portion is rotationally diametrically opposed to the first guide portion so that the opposed guide surfaces together provide about 360° of guide surface adjacent the tubing internal cylindrical surface so that thereby as the sucker rod to which the guide is affixed is reciprocated, the guide surfaces not only support the sucker rod centrally within the tubing but scrape loose accumulated paraffin from the entire cylindrical tubing wall.
The opposed guide surfaces are elevationally displaced with respect to each other to provide a pair of diametrically opposed fluid flow passageways which freely permit the flow of fluid past the sucker rod guide.
In a preferred embodiment, the guide surface on each of the guide portions is substantially in a teardrop form—that is, having a semi-cylindrical surface with an arc at one end that is about 180° with the arc of the guide surface tapering to a few degrees at an opposite end. The teardrop shaped guide surfaces are reversed with respect to each other providing non-linear fluid flow passageways therebetween. In another embodiment, the guide surface of each of the guide portions is substantially of a diamond shape in configuration with pointed upper and lower ends. In still another embodiment each of the guide portions has a guide surface t hat i s semi-cylindrical with generally planar surfaces at the upper and lower ends, the planar surfaces being generally taken in planes that are at an acute angle relative to the longitudinal axis of the sucker rod to which the guide s are affixed. In all cases, irrespective of the configuration of the guide portions they are rotationally directly opposed and oppositely elevationally oriented with respect to each other to provide flow channels therebetwee
Gable & Gotwals
Johnson Paul H.
Neuder William
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