US2143746A

US2143746A - Packing element

Info

Publication number: US2143746A
Application number: US162435A
Authority: US
Inventors: Ferdinand J Spang
Original assignee: Individual
Current assignee: Individual
Priority date: 1937-09-04
Filing date: 1937-09-04
Publication date: 1939-01-10
Anticipated expiration: 1956-01-10

Description

lNvl-:N TOR F. J. SPANG PACKING ELEMENT Filed Sept. 4, 1937 Jan. 14o, 1939,

Patented Jan. 1o, 1939 UNITED STATES PATENT OFFICE Application September 4, 1937, Serial No. 162,435

9 claims. (ol.` 16e-L10) lmethod of making the same.

Well packers, which are used in separating the strata of a well bore in the production of natural gas and oil, are equipped with a resilient packing element which is adapted to be expanded or deformed by suitable-means to seal the well bore. Such packing elements are generally made of either a para rubber base or of synthetic rubber and have a relatively consistent uniformity (i. e., degree of resiliency) at any cross section throughout theA length of the element. As the material from which the element is made has low resistant qualities to deforming force, any slight variation in uniformity of the packing element causes that particular area of the element to be deformed in advance of the other parts thereof, and this early or premature deformation usually occurs at the upper end of the packing element and in the early stages of setting the packer. Consequently, sub-` sequent deformation of the packing element can only be accomplished by sliding the prematurely deformed portion along the Walls of the well. bore until the packer is fully set. Such sliding movement of the deformed portion of the packing element frequently ruptures the element or causes it to wrinkle in such a way as to prevent the eiective sealing of the well bore.

The primary object of this invention is vto provide a packing element for a well packer which has different degrees of resiliency throughout its entire length and which is capable of being de-V formed in pre-arranged sgiuences. r

Another object is to provide a` resilient packing element for a well packer in which the bottom or lowermost portion of the packer is deformed in vthe earliest stages of its setting and such deformation continues progressively from the bottom to thetop until the element has been completely deformed or set.

A further object is to provide a resilient unitary packing element for well packers having portions of varying degrees of hardness whereby the element may be progressively deformed by applying to the element forces of progressively increasing magnitude.

A still further object is to provide a new and novel method of fabricating a yieldable packing element for a well packer.

These and other objects which will hereinafter be made apparent to those skilled in this particular art are accomplished by means of this invention,one embodiment of which is described in the following specication and illustrated in the accompanying drawing, wherein:-

Figure 1 is a view in side elevation (partly in section) of a packing element for a well packer;

Fig. 2 is a view of a rubber sheet from which the packing element is laminated;

Fig. 3 is a view of one-half of the sheet shown in Fig. 2 and cut in such a way as to form a right angle triangle; l

Fig. 4 is a view of a prepared sheet of resilient material from which the packing element is laminated;

Fig. 5 is a sectional view taken on the line V`V of Fig. 4;

Fig. 6 is a view showing the prepared sheet of resilient packing material being wound in laminations on a curing mandrel, a portion thereof being shown in section for convenience of illustration;

Fig. 7 is an enlarged view partially in section of the completely laminated element before curing; and

Fig. 8 is a view illustrating another method of fabricating my improved packing element. y

Referring to Fig. -1 of the drawing, I0 represents a resilient packing element made in accordance with my invention and comprises an annular body I I formed of rubber or any other suitable resilient material having metallic rings I2 at each end thereof to which the body I I is secured by a series of fabric strips I3 which extend through slots I4 in the rings I2 and have their ends embedded in or molded into the body II. The rings I2 are also provided with a series of countersunk openings I5 by means of which the packing element is secured to the couplings of a suitable well packer (not shown).

In fabricating or building a packing element in accordance with my preferred method, a rectangular sheet of crude rubber A having the desired degree of hardness is cut along a diagonal line (represented by the dotted line in Fig. 2) to divide the sheet into two right angle triangles of equal size and of the shape shown in Fig. 3.

A second sheet of crude rubber of similar size and shape to that shown in Fig. 2 but having a different degree of hardness than the sheet A is also cut along the diagonal line to provide two right angle triangle pieces B. A triangular piece of the A sheet is then joined to a triangular piece of the B sheet by overlapping the two pieces along the hypotenuses thereof, as at i6 (Fig. 5).,to form a single rectangular sheet,. one-half oi' which is relatively soft in comparison with the other half of the sheet. The sheet? prepared from the triangular pieces A and B is then wound around a mandrel Il having removable thrust couplings I8 at each end thereof on which the two metallic rings I2 of the packing element have been previously mounted. The mandrel Il with the endA couplings I8 and the rings I2 in place thereon is mounted for rotation between two end center supports 20 preparatory tp the winding of the sheet A-B thereon. During the process of winding the sheetl A-B on the mandrel between the rings l2, the fabric strips I3 are placed in the slots I8 and the ends thereof are positioned between the layers of rubber formed during the' winding of the sheet on the mandrel. Y

After the sheet A-B has been completely wound on the mandrel between the rings I2 and the entire space between the two rings has been filled with crude rubber, the outer surface of the rubber on the mandrel is wrapped 4with strips of cloth which hold it in place thereonand the rubber is cured while so held in position on -the mandrel. If desired, the mandrel with the rubber thereon may be placed in a mold to cure the packing element.

As shown ,in Fig. 7 after the sheet A-B has been wound on the mandrel, the sheet A tapers from the top to the bottomand the sheet B tapers upwardly from the bottom toward the top of the packing element, and, as a result of the difference of hardness of the sheets A-B, the maximum hardness of the packingrelement is concentrated at one end and the maximum softness of the,material of the packing element is concentrated at the other end of the packing element.

In Fig. 8, I have disclosed an alternative method of making my improved packing element from two independent and separate sheets of vrubber of different degrees of hardness. In accordance with this modication, a triangular sheet of rubber 25 having one right angled corner is so wound on the mandrel I'I-an edge of the sheet terminating in such right angled corner being first placed lengthwise of the mandrel-that the numlber ofl layers on the mandrel gradually increases from one end to the other of the mandrel, and each succeeding` layer is of shorter length than the preceding one. After the sheet 25 has been completely wound on the mandreL- a second sheet of rubber 26, of the same size and shape as the sheet 25 but having a different, degree of hardness from that of the sheet 25, is positioned on the mandrel with the apex thereof adjacent the first layer of the sheet 25 and the sheet 2,6 is then wound on the mandrel and on the sheet 25. As the sheet 26 is wound on the mandrel in this position, each successive layer is longer than the preceding one,and since'the two sheets together form a rectangle, the ends of succeeding layers abut against the ends of the layers of the first sheet'whereby a cylindrical body is secured which is cured in the same manner as heretofore described.

The packing element is adapted to be arranged on the packer in suchvmanner that the softest part of the packing element is lowermost Consequently, when end pressure is applied to the rings I2 to expand or'deform the packing element, the lower end, which is predominantly of soft rubber, is first deformed and as the pressure increases` the deformed area increases. progressively until the entire sheet of rubber of the` Y packing element has assumed its deformed condition.' .b 1.x u

While I have shown the'sheet A-B -as being a amargo combination of two separately formed sheets of material, it is to be understood that the same results may be accomplished by applying a softening or hardening coat to one diagonal half of a sheet of rubber to make that half harder or softer than the other half of the sheet. For example, a portion of a`sheet of rubber may be coated with a mixture of lamp black and clay to harden that half of the sheet or it may be painted or coated with a solution of pure para rubber and crude rubber to make such painted half soiter than the unpainted half.

From the foregoing description of my invention, it is apparent that I have provided a packing element which has a' minimum hardness at one end and a maximum hardness at the other end, and that as a result of the difference in the hardness of the opposite ends of the packing element, one end of the packer may be set by applying a light load to the element of the packer, another portion may be set by applying a larger load above therpacker, and still another portion of the element may be set by applying still greater loads thereto. Consequently, the packer is deformed progressively by the application of progressively increasing forces and since the element is so arranged that the portionof minimum hardness is at the bottom the deformation of the packing element takes place from the bottom toward the top whereby in the early stages of setting the packer the lower end of the element is moved into contact with the wall of the well bore and as the setting of the packer progresses portions of the packing element above the lower end are progessively deformed and moved into contact with the wall of the Well bore /until a complete seal is obtained. It should also ying element, during the setting of the packer,

takes place from the bottom toward the top thereof, no portion of the deformed packing element is moved in sliding engagement along the wall of the well bore and, consequently, no danger or injury to the packing element is occasioned during the setting.

Having thus described my invention, what I claim as new and desire to secure by Letters Patnt'is:

1. A packing element having a resilient body section of diiferent degrees of hardness with the minimum hardness at the lower end and the maximum hardness at the upper end thereof.V

2. A packing element comprising a tubular resilent body of progressively varied hardness from one end to the other.

3. A resilient packing element of progressively increasing hardness from one end to the other of such element.

4. A packing element comprising a tubular body section and metallic end sections attached to said body section', said body section increasing in hardness progressively from the bottom to the top thereof.

5. A packing element comprising a tubular body of resilient material, a pair of metallicvend rings and means for securing said body to said end rings, said body being softer at one end than at the other with the degree of softness decreasing progressively from the softest end to the opposite end.

6. A packer rubber composed of at least two uniform wall thickness vthroughout its entire length.

7. A packer rubber composed of two tapered sections of different degrees of resiliency vulcanized together to provide a sleeve of uniform Wall thickness throughout its length.

8. A packer rubber comprising a. tapered section of relatively soft rubber and a section of substantially harder rubber tapered to complement the relatively soft section, said sections being vulcanized together to provide a. sleeve of uniform Wall thickness throughout the length thereof.

9. A packer rubber composed of complementary tapered sections of different degrees of resiliency vulcanized together to provide an integral sleeve of uniform wall thickness throughout its length.

FERDINAND J. SPANG.