Patent Grant
9840880
The present application relates to casing centralizers, and more specifically to a casing centralizer with improved material properties that is formed by compression molding a bulk molding compound.
Non-metallic casing centralizers for use in casing oil and gas wells are known in the art, but suffer from material deficiencies that render them unacceptable for the downhole environment where they are used. The material properties required for such applications are not defined.
A casing centralizer is provided that includes a cylindrical base and a plurality of blades extending from the cylindrical base, wherein the plurality of blades and the cylindrical base are compression molded as a single piece from a mineral filled, glass and specialty fiber reinforced polyester molding compound, such as ST-20250 (Bulk Molding Compounds, Inc., West Chicago, Ill.).
Other systems, methods, features, and advantages of the present disclosure will be or become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present disclosure, and be protected by the accompanying claims.
Aspects of the disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views, and in which:
In the description that follows, like parts are marked throughout the specification and drawings with the same reference numerals. The drawing figures might not be to scale and certain components can be shown in generalized or schematic form and identified by commercial designations in the interest of clarity and conciseness.
Casing centralizer 100 is compression molded using a bulk molding compound, unlike prior art non-metallic centralizers that are injection molded or extruded. Compression molding using a bulk molding compound allows casing centralizer 100 to have superior material properties for use within the harsh environment that casing centralizers are exposed to in oil and gas wells. In one exemplary embodiment, the bulk molding compound can be a mineral filled, glass and specialty fiber reinforced polyester molding compound suitable for compression and stuffer injection molding.
Typical properties for the molding operation can include a temperature of 270 to 370° F., with mold shrinkage of 0.001 to 0.004 mil/in, and a molded specific gravity of 1.65 to 1.95. The mechanical/physical properties of the bulk molding compound that make centralizer 100 suitable for use in oil and gas wells include a flexural strength of 18,000 to 28,000 psi, a flexural modulus of 1.4 to 2.2*106 psi, a tensile strength of 5,000 to 12,000 psi, a compressive strength of 18,000 to 28,000 psi, an impact strength, notched Izod, of 6 to 14 ft-lb/in and a shear strength of 2,800 to 6,800 psi. The electrical properties include an arc resistance of greater than 180 seconds, a comparative tracking index of greater than 600 volts, and a short time dielectric strength of 325 to 425 volts/mil. The thermal properties include a heat deflection temperature at 264 psi of greater than 450° F.
In one exemplary embodiment, the unsaturated polyester bulk molding compound can be formed by combining 31% resin system with 37.5% filler System and 31.5% chopped strand reinforcement. The molding process can include using a 400 ton press for compression molding, with temperatures of 300 to 330° F. and less than 10 minutes for the cure cycle. In another exemplary embodiment, the unsaturated polyester bulk molding compound can comprise a suitable combination of the following: <17% styrene; (10% vinyl toluene; <20% unsaturated polyester; <2% zinc stearate; <2% divinyl benzene; <70% calcium carbonate; <70% alumina trihydrate; <29% kaolin; <2% calcium stearate; <65% calcium metasilicate; <35% fibrous glass; <2% zinc sulfide; <2% iron oxide black; <3% carbon black; <4% titanium dioxide; <4% polyethylene; <3% talc and <5% polystyrene. In another exemplary embodiment, casing centralizer 100 can be made from ST-20250, available from Bulk Molding Compounds, Inc., 1600 Powis Court, West Chicago, Ill. 60185.
It should be emphasized that the above-described embodiments are merely examples of possible implementations. Many variations and modifications may be made to the above-described embodiments without departing from the principles of the present disclosure. All such modifications and variations are intended to be included herein within the scope of this disclosure and protected by the following claims.
The present application is a continuation of U.S. patent application Ser. No. 14/738,697, filed Jun. 12, 2015, now U.S. Pat. No. 9,422,774; which is a continuation of U.S. patent application Ser. No. 13/873,004, filed Apr. 29, 2013, now U.S. Pat. No. 8,701,759; which is a continuation of U.S. patent application Ser. No. 13/803,088, filed Mar. 14, 2013, now U.S. Pat. No. 9,057,229, which is hereby incorporated by reference for all purposes as if set forth herein in its entirety.
| Number | Name | Date | Kind |
|---|---|---|---|
| 8701759 | Hansen | Apr 2014 | B1 |
| Number | Date | Country | |
|---|---|---|---|
| 20160356100 A1 | Dec 2016 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 14738697 | Jun 2015 | US |
| Child | 15243749 | US | |
| Parent | 13873004 | Apr 2013 | US |
| Child | 14738697 | US | |
| Parent | 13803088 | Mar 2013 | US |
| Child | 13873004 | US |
