Note: Descriptions are shown in the official language in which they were submitted.
CA 02281237 1999-09-O1
This invention relates to well tools and more particularly to
rod guides rigidly fixed to the shanks of rods of a sucker rod
string reciprocable in a well tubing to operate a well pump.
BACKGROUND OF THE INVENTION
Rod guides or centralizers which are rigidly mounted on the
shanks of the rods of a reciprocable sucker rod string are used to
hold the rods in substantially concentric position in a well tubing
in order to minimize wear or erosion of the well tubing by
preventing contact of the sucker rods and particularly their
enlarged end connectors with the internal surfaces of the well
tubing. The rod guides should provide large areas of contact
thereof with the internal surfaces of the well tubing to minimize
the force per unit area of contact between the rod guides and the
internal surfaces of the well tubing, thus minimizing their
erosion,, and also to provide large volumes of the erodable
substance of the rod guide to increase the length of operation of
the rod guides before erosion of the rod guides due to such sliding
contact thereof with the internal surfaces of the tubing requiring
their replacement. It is desirable however that the centralizers
offer low resistance to the flow of liquids therepast during the
reciprocation of the rod string and operation of the pump thereby
in order to achieve optimum rates of production of well fluids and
-1-
CA 02281237 1999-09-O1
to minimize the energy necessary to reciprocate the sucker rod
string and operate the pump. The rod guides become ineffective
when outer portions thereof are eroded to such an extent that they
do not prevent contact of enlarged portions of the sucker rod
string, such as at the couplings between adjacent ends of the rods
of the rod string with the internal surfaces of the well tubing.
The fixed centralizers or rod guides may act as tubing scrapers in
portions of the well tubing where waxes, tars or other substances
may come out of solution and tend to deposit on the internal
surfaces of the well tubing. Centralizers and/or scrapers of this
type have been illustrated in United States Patent No. 5,452,760,
United States Patent No. 5,806,591 and the references cited
therein.
OBJECTS OF THE INVENTION
Accordingly it is an obj ect of this invention to provide a new
and improved rod guide which provides large areas of contact with
the well tubing to minimize the force per unit area in contact
therewith but which provides a relatively large cross-sectional
area of flow of fluid therepast in the well tubing.
Another object of the invention is to provide a rod guide, of
the type described, having a tubular body rigidly fixed in the
shank of a rod and a plurality of ribs extending radially outwardly
-2-
CA 02281237 1999-09-O1
of the body, the ribs having a enlarged radially outwardly disposed
portions of greater circumferential width than at their connections
with the tubular body.
Another object is to provide a rod guide, of the type
described, wherein the ribs have circumferentially outer enlarged
portions which combine with the tubular body to form large general
passages which open outwardly of the tubular body between adjacent
spaced ribs.
SUMMARY OF THE INVENTION
A sucker rod having a tubular body rigid with the shank of a
sucker rod having circumferentially spaced ribs extending radially
outwardly from the tubular body the ribs having grooves in sides
thereof which increase the cross-sectional area of the flow passage
betraeen the rod guide and the internal surfaces of a well tubing
while providing a large area of contact between the ribs and the
internal surfaces of a well tubing and providing a large volume of
substance which may erode or wear away due to the sliding
frictional contact of the outer circumferential surfaces of the
ribs with the internal surfaces of the well tubing.
DESCRIPTION OF THE DRAWINGS
Additional objects of the invention will become apparent from
the reading of the following description of rod guides embodying
-3-
CA 02281237 1999-09-O1
the invention and reference to the accompanying drawings wherein:
Figure 1 is a fragmentary longitudinal view of a sucker rod
string provided with rod guides embodying the invention;
Figure 2A is a sectional view taken on line 2A-2A of Figure
1;
Figure 2B is a sectional view taken on line 2B-28 of Figure
1;
Figure 3 is a sectional view taken on line 3 Figure l;
Figure 4 is a side view of another rod guide embodying the
invention;
Figure 5 is another side view of the rod guide of Figure 4;
Figure 6 is a longitudinal sectional view taken on line 6-6
of Figure 4;
Figure 7 is a sectional view taken on line 7-7 of Figure 5,
and
Figure 8 is a view taken on line 8-8 of Figure 5.
-4-
CA 02281237 1999-09-O1
Referring now particularly to Figures 1-3 of the drawings, the
rod guide 10 embodying the invention are shown rigidly mounted on
the shank S of the sucker rod whose ends are secured to adjacent
ends of adjacent rods of the tubing rod string by couplings C. The
sucker rods of the string have opposite enlarged end portions
provided with threaded pins means of which their threaded couplings
C secure the rods to another as is well known to those skilled in
the art.
The rod guide has a tubular body 11 molded on and rigid with
the shank and have two ribs 13 and 14 which extend radially
outwardly in opposite directions from the tubular body. These ribs
have longitudinally side surfaces 15 and 16 which lie in a plane
diametric with the longitudinal central axis of the shank of the
rod. The ribs 13 and 14 have circumferentially enlarged outer
portions 18 and 19, respectively, which define with the tubular
body longitudinal grooves or passages 20 and 21 which open to the
longitudinally extending spaces between the ribs l3 and 14 and the
third rib 17 which also extends radially outwardly of the body.
The other sides 22 and 23 of the ribs 13 and 14, respectively,
define a longitudinal channel for the purpose as described and
illustrated in United States Patent No. 5,806,591.
It will be apparent to those skilled in the art, that the mold
in which the rod guide is formed about the shank has two
-5-
CA 02281237 1999-09-O1
components, one having a cavity which forms the lower half of the
rod guide which includes the ribs 13 and 14 as seen in Figure 2A
and the other which forms the top half of the rod guide, which
includes the third rib 17.
The rod guide has beveled end shoulders 26 and 27 which slope
in opposite directions from the outer surface to the rod guide to
the rod shank.
It will be seen in Figure 1 that the channels 20 and 21 extend
radially outwardly a distance substantially equal or somewhat less
than the radial distance the coupling C extends outwardly of the
shank.
The ribs wear due to their sliding abrasion abrasion with the
internal surfaces of the well tubing during the reciprocation of
the sucker rod string. The rods thereof can be displaced further
from central alignment within the well tubing as they wear and will
permit the enlarged portions of the sucker rod string, the
couplings, to slidingly engage the internal surfaces of the well
tubing. Inasmuch as it is much more expensive to replace the
tubing than the rod guides whose ribs have been abraded to the
point where they permit the coupling to contact the internal
surfaces of the well tuning than to replace such guide rods or to
replace the sucker rod whose guides have been abraded to such
degree.
It will be noted that the channels 20 and 21 extend radially
-6-
CA 02281237 1999-09-O1
outwardly of the central axis of the rod shank a distance
substantially equal to or slightly less than the distance the
couplings outer surfaces of the couplings extend radially from the
central axis of the rod.
It will now be seen that the provision of the channels 20 and
21 substantially increases the cross-sectional area of the fluid
passage between the internal surfaces of the well tubing and the
rod guide which leads to lesser resistance to flow of the well
fluids past the rod guide and decreases the energy required to
maintain a desired rate of flow of the well fluids by the action
of the pump during the reciprocation of the sucker rod string.
Referring now to Figures 4-8 of the drawings, another rod
guide 50 embodying the invention includes a tubular body 51 rigidly
mounted on the shank of a sucker rod, as by molding, having four
ribs 54, 55, 56 and 57 integral therewith. The four ribs extend
longitudinally angularly relative to the central longitudinal axis
of the rod and their outer surfaces lie in a cylindrical plane
concentric with the central longitudinal axis of the rod. The ribs
54 have side surfaces 61 and 62 and the rib 55 has parallel side
surfaces 63 and 64. The rib 56 has channel 71, 72 and the rib 57
has side channels or grooves 73 and 74 in order to provide a
greater cross-sectional area of the fluid flow or passage past the
rod guide when it is in a well tubing.
_7_
CA 02281237 1999-09-O1
It will now be seen that a new and improved rod guides have
been illustrated and described which provide a relative large
sectional area fluid flow passage past the rod guide when it is
mounted on the rods of a sucker rod string while providing a large
area of contact of the guide ribs with the internal surfaces of a
well tubing.
It will further be seen that as the ribs erode they permit a
greater displacement of the rib string from the central position
in the well tubing and that they become ineffective when they wear
to such an extent that they permit portions of the rod string as
at couplings, to engage to contact the internal surfaces of the
well tubing.
It will further be known to those skilled in the art that in
order to prolong the usable line of these guides the rod string may
be rotated at the surface by suitable means to insure uniform wear
or erosion of the ribs and thus prolong the useful life of the rod
guides.
The foregoing descriptions are explanatory only in changes of
the details of the constructions illustrated may be made by those
skilled in the art within the scope of the appended claims without
departing from the spirit of the invention.
_g_
