Wells – Packers or plugs – Flow stopping type; e.g. – plug
Reexamination Certificate
1998-09-23
2001-08-28
Foelak, Morton (Department: 1711)
Wells
Packers or plugs
Flow stopping type; e.g., plug
C166S195000, C521S054000, C521S135000, C521S178000, C523S219000
Reexamination Certificate
active
06279652
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to heat insulation compositions and methods, and more particularly, to epoxide insulation compositions and methods of using the compositions for insulating fluid containers such as pipe.
2. Description of the Prior Art
Fluid containers such as vessels and pipes are often insulated whereby the fluids therein do not readily gain or lose heat by heat transfer through the walls of the container. Insulated pipelines and pipeline bundles made up of one or more pipelines positioned within a larger diameter outer sleeve have been developed and used heretofore. Such pipelines are commonly utilized for transporting oil and gas produced from wells underwater or underground. The pipelines have heretofore been insulated by filling the spaces between the pipelines and the outer sleeves with insulating compositions such as foamed hydraulic cement compositions.
When a foamed hydraulic cement composition is utilized as insulation between a pipeline and an outer sleeve, the cement sheath formed is subjected to various shear and compressional stresses during the life of the pipeline. For example, when pressures and/or temperatures, the pipeline expands both radially and longitudinally which places stresses on the cement sheath often causing cracks and loss of insulation properties therein. Another stress condition and loss of cement sheath insulation properties results from water being trapped in channels or pockets therein and from exceedingly high pressures which occur inside the cement sheath due to thermal expansion of the water. The thermal expansion often occurs as a result of high temperature differentials created during fluid production which cause the water to be vaporized and create high pressures. The high pressures can exceed the collapse pressure of the pipeline and/or cause leaks in the outer sleeve. Still other conditions occur which cause loss of insulation properties as a result of the stresses exerted on the completed pipeline, cement composition and outer sleeve during the transport, installation or other movements of the pipeline.
Thus, there is a continuing need for improved heat insulation compositions which are resilient whereby they can resist failure as a result of movements of the insulated container to which they are applied.
SUMMARY OF THE INVENTION
The present invention provides improved heat insulation compositions and methods which meet the needs described above and overcome the shortcomings of the prior art. The improved heat insulation compositions of this invention are basically comprised of an epoxide containing liquid, an insulating material and an epoxide hardening agent. Upon hardening, the compositions provide good insulation properties whereby a minimum of heat transfer takes place through the walls of the fluid containers to which they are applied and the compositions are highly flexible whereby they resist failure as a result of container movements caused by expansion, contraction and the like. For example, when the insulating compositions of this invention are applied to underwater gas or oil pipelines, the insulating properties of the compositions prevent condensation of the gas or precipitation of paraffins from the oil in the pipelines while the highly resilient nature of the compositions prevents failures due to pipe movements.
The methods of this invention basically comprise the steps of preparing an insulation composition comprised of an epoxide containing liquid, an insulating material and an epoxide hardening agent, placing the insulation composition adjacent to the surfaces of a fluid container, and then allowing the insulation composition to harden.
It is, therefore, a general object of the present invention to provide improved heat insulation compositions and methods of heat insulating a fluid container therewith.
Other and further objects, features and advantages of the present invention will be readily apparent to those skilled in the art upon a reading of the description of preferred embodiments which follows.
DESCRIPTION OF PREFERRED EMBODIMENTS
As mentioned, the present invention provides improved heat insulation compositions and methods. The insulation compositions provide good insulation properties whereby very little heat transfer takes place into or from a fluid container such as a vessel or pipeline insulated therewith. In addition, the heat insulation compositions of this invention are highly resilient and therefore do not fail as a result of movements of the insulated fluid container. The insulation compositions and methods of this invention are particularly suitable for insulating pipelines through which hydrocarbons from oil and gas wells are flowed.
The heat insulation compositions of the present invention which have good insulation properties and are highly resilient after hardening are comprised of an epoxide containing liquid, an insulating material and an epoxide hardening agent. While various epoxide containing liquids can be utilized, a preferred such liquid is comprised of a liquid epoxy resin and a diluent. Liquid epoxy resins produced from epichlorohydrin and bisphenol A (4,4′-isopropylidenediphenol) are readily available and are suitable for producing a pumpable composition which hardens into an impermeable, high strength solid. Particularly suitable such liquid epoxy resins have molecular weights in the range of from about 200 to about 1,000 and have a one gram equivalent of epoxide per about 100 to 200 grams of epoxy resin. A more preferred such liquid epoxy resin has a molecular weight of about 340, a one gram equivalent of epoxide per about 185 to 192 grams of resin and a viscosity at 25° C. of about 100 to 160 poises. A liquid epoxy resin having these properties is commercially available under the trade name “EPON® 828” from Shell Chemical Company of Houston, Tex.
The liquid diluent is included in the liquid epoxy resin so that it will have a low enough viscosity to be pumpable. A hydrocarbon diluent which can be utilized is comprised of aromatic hydrocarbons having the formula C
6
H
2
(R)
4
wherein R is hydrogen or a straight or branched chain alkyl radical having from 1 to 3 carbon atoms with at least one, and more preferably two, of the R's being alkyl radicals. Examples of such aromatic hydrocarbons include, but are not limited to, toluene, ethylbenzene, n-propylbenzene, isopropylbenzene, n-butylbenzene, isobutylbenzene, cyclohexylbenzene, n-hexylbenzene, xylene, diethylbenzene, 2-chloro-p-xylene, diisopropylbenzene, 2-nitro-p-xylene, cymene, durene, isodurene, trimethylbenzene, triethylbenzene, dibutylbenzene, penta-methylbenzene, 1-pentyl-3-ethylbenzene, p-pentyltoluene, 1-hexyl-3-isobutylbenzene, m-hexyltoluene, 1-heptyl-3-isopropylbenzene, p-heptyltoluene, 1-heptyl-3-ethylbenzene, 1-octyl-3-butylbenzene, 1-octyl-3-propylbenzene, p-octyltoluene, 1-nonyl-3-ethylbenzene, p-nonyltoluene, 1-dodecyl-3-ethylbenzene, p-isodecyltoluene, 1-decyl-3-isotridecylbenzene and mixtures thereof.
A particularly suitable diluent which is presently preferred is comprised of a mixture of hydrocarbons containing from about 50% to about 75% of one or more of the above described aromatic hydrocarbons by weight of the diluent. A preferred such diluent is commercially available under the trade name “CYCLO SOL® 63” from Shell Chemical Company of Houston, Texas. When utilized, the liquid hydrocarbon diluent is mixed with the liquid epoxy resin in an amount in the range of from about 25% to about 50% by weight of the epoxy resin. More preferably, the diluent is mixed with the epoxy resin in an amount of about 27% by weight of the epoxy resin.
Another diluent which can be utilized in lieu of the above described hydrocarbon diluent is a low viscosity epoxide containing liquid. Preferred such low viscosity epoxide containing liquids are the diglycidyl ether of 1,4-butanediol, the diglycidyl ether of neopentyl glycol, the diglycidyl ether of cyclohexane dimethanol and mixtures thereof. A suitable epoxide containing liquid comprised o
Chatterji Jiten
Cromwell Roger S.
Onan David D.
Dougherty, Jr. C. Clark
Foelak Morton
Halliburton Energy Service,s Inc.
Roddy Craig W.
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