US2539000A - Oil well pump plunger - Google Patents

Description

Jan. 23, 1951 R. c. WILLIAMS on. wsu. PUMP PLuNGx-:R

Patented Jan. 239 1951 UNITED STATES PATENT OFFICE OIL WELL PUMP PLUNGEB. Roy c. williams, wayne, ohio Application June 26, 1948, Serial No. 35,341

4 Claims.

This invention relates to oil well pump plungers and is particularly directed to a plunger suitable for pumping a sand laden liquid.

The primary object of the inventionis to provide an oil well pump plunger which will have a greatly increased operating life over plungers now 1n use.

It has heretofore been the practice to, utilize pump plungers having removablepacking elements thereon and to replace the packing when the plunger becomes sufficiently worn that renewal was necessary in view of excessive leakage past the plunger. In certain sandy fields such renewal has frequently been required after only a few weeks of operation. Renewal of the packing elements, of course, requires that the entire string of sucker rods be pulled from the well and dismantled even though the repacking of the plunger itself is a relatively minor operation. In deep wells where several thousands of .feet of sucker rods are used the time and labor required for such an operation is almost prohibitive unless the well is capable of suiliciently high production to justify the expensive and time consuming'renewal of the pump parts.

Many expedients have been proposed to keep sand from entering the working barrel where it can injure the packing and many forms of packing have been resorted to, but the presently known devices are still limited in their working life to such a point that many wells cannot be economically operated in the face of the high labor costs involved in pump repairs.

The present invention represents an improvement over known devices and comprises broadly a tightly fitting center portion of a pump plunger with grooved sand excluding sections above and below the tightly fitting area. The relative dimensions of the grooved sections are such that they preferably coincide with that portion of the plunger which leaves the working barrel at each working stroke. Thus if the stroke of the plunger under normal operation is such that at each working stroke a portion of the plunger one foot in length extends above the working barrel at the upper limit of the stroke while at the lower limit ci the stroke a length of the plunger equal to.

one foot extends below the working barrel, these sections are tted with sand grooves as hereinafter described. There is thus a center portion which never leaves the working barrel and this portion, as above stated, is made to iit tightly with respect to the barrel without the use of flexible packing elements.

A preferred form of the invention is shown in the accompanying drawings in which:

Fig. 1 is a central vertical section, with parts in full, of a pump plunger embodying the present invention; Fig. 2 is an elevational view of the complete plunger alone, and Fig. 3 is a detaildiagrammatic view of a typical sand groove.

Referring to the drawings the plunger is shown operating in connection with a working barrel I which extends from point A to point B. The working barrel is suspended at the bottom of a string of tubing in accordance with the usual practice and may carry any of the usual auxiliary devices at its lower end for engagement with a surrounding casing. At its extreme lower end the stationary barrel of the pump carries a standing valve cage 3 in which the usual upwardly opening check valve 5 is disposed.

The invention is particularly directed to the plunger element of the pump which includes an upper valve cage 1 in which the usual ball check valve 9 operates. On the downward stroke of the pump, the ball valve 9 is forced open while on the up stroke of the pump this valve is closed while valve 5 opens, admitting uid to the pump barrel to be forced above the pump barrel into the tubing on the next down stroke. The plunger has a center bore -II through which oil ows and this passage is, of course, controlled by the' ball check valves 5 and 9.

In one form of the invention the outer surface of the plunger is composed of ahelically wound, replaceable, member which is disposed over a surface I3 of the plunger which acts as a mandrel for the helical member. This surface may be made tapered throughout its length or may be made cylindrical as shown in the drawings. If a tapered mandrel is used certain adjustments may be made merely by forcing the helical packing member longitudinally of the mandrel although such adjustment is not necessary in the present instance.

The helical packing member comprises a center section in which the helical convolutions lie closely adjacent each other to form a substantially continuous, smooth cylindrical surface which lits very closely within the working barrel and which acts to seal the pump plunger against leakage of oil downwardly.

This surface is designated l5 in the drawings and comprises that area between points C and D along the length of the plunger. In general the surface l5 coincides with that portion of the plunger which remains constantly in the barrel during pumping.

Above and below the smooth packing sections the helical convolutions are grooved at the edges to form square bottomed sand grooves I6. The depth of the grooves is approximately equal to their lateral width and in a specific example the width and depth of the grooves have been approximately 040 inch with a total width of the strand of helix equal to .110 inch. In elds where the sand grains are larger than average, a wider and deeper groove may be cut, but for average conditions the proportions set forth have been satisfactory. The helical groove I6 extends continuously from near the extremity of the plunger to the packing area I5. As above stated this area coincides approximately with that portion of the plunger which leaves the barrel during a working stroke. For example, if the plunger is four feet long and is operated with a two foot stroke, one foot at the top and one foot at the bottom will leave the working barrel at each reciprocation while the center area, two feet in length, remains constantly in sealing relation to the barrel.-

Sand particles suspended in the oil are forced into the grooves I6 as the plunger reenters the barrel since the flat helical surface fits tightly against the barrel. As the grooves are continuous, a washing action is set up by which sand particles trapped by the grooves are forced out into the well. Those particles which do enter the barrel are housed within the confines of the groove and do not score the barrel. Plungers of this type have operated for more than three months in sandy Wells is which the normal interval between repacking of plungers is about three weeks. At the end of the three months period no appreciable wear has been observed.

Any suitable holding means may be used to grip the ends of the helical packing element, which ends are designated 2li-2l in the drawing. It is, of course. necessary to nx the ends soiirmlyv that no flexure of the helix takes place so that its diameter remains constant. In the preferred form, the outer mandrel surface is tapered at the area where the ends o1' the helical packing fall, and the ends are forced against the mandrel by internally tapered collars 22 forced inwardly of the mandrel by nuts 23.

It is, of course, not necessary to form the sand grooves as part of a replaceable packing element but such grooves may be cut in the surface of an otherwise solid, cylindrical plunger. The replaceable element, however, is more economical to make and use. Further, it is not essential that all of the grooved plunger area leaves the barrel at each reciprocation of the pump. The lower grooves will be self cleaning if only the last turn is exposed so that sand will wash down into the well rather than be trapped to score the barrel.

The operation of the invention has been explained in connection with the description of the parts. While a specific embodiment has been shown and described, it should be expressly understood that numerous modifications and changes may be made without departing from the scope of the appended claims.

What I claim is:

1. In an oil well pump having a cylindrical working barrel and a plunger cooperating therewith, which plunger in its pumping reciprocation moves partially out of the barrel at the upper and lower ends of its stroke, the improvement comprising substantially continuous helical grooves in those surfaces of the plunger which leave the barrel, said grooves acting to trap abrasive mattei' and prevent its entrance between the plunger and barrel surfaces, and a sealing surface intermediate the grooved surfaces.

2. In an oil well pump having a cylindrical working barrel and a plunger cooperating therewith, which plunger in its pumping reciprocation moves partially out of the barrel at the upper and lower ends of its stroke, the improvement comprising a helical packing member forming the active surface of said plunger, said member presenting a smooth, flat sealing surface throughout an intermediate area corre-` sponding substantially to that area which remains in cooperation with the barrel during a working stroke, and said member having substantially continuous helical grooves formed at the meeting edges of the turns of the helix extending from the ends of said member to said sealing surface.

3. A pump in accordance with claim 1 in which said grooves have substantially the same depth and width.

4. In an oil well pump having a cylindrical working barrel and a plunger cooperating therewith, which plunger in its pumping reciprocation moves partially out of the barrel at the upper and lower ends of its stroke, the improvement comprising a metallic helical member forming the active surface of said plunger, said member presenting a smooth, flat sealing surface throughout an intermediate area corresponding substantially to that area of the plunger which remains at all times within the working barrel, and said member having substantially continuous helical grooves formed therein extending from the ends of said member to said sealing surface.

ROY C. WILLIAMS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 616,308 Forsyth et al Dec. 20, 1899 1,161,851 Downie Nov. 30, 1915 1,764,482 Yungling June 17, 1930 2,018,204 Evans et al. Oct. 22, 1935 2,154,331 Hathcock Apr. 11. 1939 2,301,319 Peters Nov. 10, 1942

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