Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Compound of indeterminate structure – prepared by reacting an...
Reexamination Certificate
2001-02-01
2002-12-03
Toomer, Cephia D. (Department: 1714)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Compound of indeterminate structure, prepared by reacting an...
C508S476000, C508S500000, C508S501000, C508S514000, C507S239000, C554S063000
Reexamination Certificate
active
06489272
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to compositions useful as lubricants for spotting fluids in well drilling operations with either oil-based or water-based muds. The compositions of the invention are non-toxic and biodegradable, are especially useful in fast hole drilling, and also function as performance extenders for corrosion inhibitors in high velocity gas, oil or water drilling, production or gathering applications. The invention also relates to a method for making the subject lubricant using a controlled mixing process and distillation under controlled conditions to remove more volatile components and promote esterification and further reaction with amine substituents.
2. Description of Related Art
International Publication Number WO 97/12947, which claims priority based on U.S. Ser. No. 08/538,262, filed Oct. 3, 1995, discloses high flash point, low vapor pressure, cleaning compositions for oil and gas wells, said compositions containing about 40 to 99 weight percent of a fatty acid alkyl ester blend and about 1 to 25 weight percent of at least one lower alkyl glycol ether. The disclosed compositions, when injected into wells, are said to produce a coating on well casings, lines, pumps, pipes and other equipment, to prevent the adhesion and accumulation of paraffins, other related soils, and scale on these parts to help retard corrosion, and to allow more efficient operation and consistent production between cleanings. Preferred fatty acid alkyl ester blends for use in the invention are selected from the group consisting of C
1
to C
8
esters of C
4
to C
22
fatty acids. Preferred lower alkyl glycol ethers are selected from the group consisting of ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl either, and mixtures thereof. The optional use of from 1 to 40 weight percent polyoxyalkylene glycol ethers is also disclosed.
Various other prior art drilling fluid additives, spotting fluids and lubricant compositions are disclosed, for example, in U.S. Pat. Nos. 2,500,163; 3,108,068; 3,298,954; 3,396,105; 4,263,465; 4,282,392; 4,436,636; 4,464,269; 4,502,963; 4,525,285; 4,587,368; 4,652,385; 4,876,017; 5,421,907; and 5,547,925.
A well lubricant composition is needed that has a low acid number, and is therefore much less likely to form calcium soaps from lime in downhole formations, which can in turn cause undesirable foaming in drilling muds. The desired composition should also be nontoxic and not susceptible to foaming during manufacture.
SUMMARY OF THE INVENTION
The composition of the invention is a well lubricant, solvent and emulsifier that is preferably formed by the sequential reaction and subsequent distillation of a tall oil fatty acid having a moderately low rosin content with a fatty alkanolamide, preferably in the presence of methyl ester of fatty acids, and most preferably when further reacted with an emulsifier such as coconut oil diethanolamide or an amide of aminoethylpiperazine (AEP) under distillation conditions facilitating the removal of water and lighter reaction byproducts . The fatty acids and oils useful in the invention can range from C
8
to C
24
, with C
12
, C
14
, C
16
, C
18
and C
20
fatty acids and oils being most preferred. The use of methyl ester is preferred because it functions as a foam supressant, diluent and amine scavenger during distillation.
The composition of the invention has low viscosity compared to tall oil amides and imidazolines, predominantly remains in the oil phase, and is easily dilutable in pale oils, white oils, polyalpha or internal olefins, methyl esters or terpenes, d-limonenes, dipentenes, and the like. In aqueous solution the invention forms a dispersion that, when static or quiescent, evolves completely to oil, not leaving a residual material to sheen or cloud the water. The composition of the invention provides strong adhesion and oil wetting to metal parts, thereby reducing wear, increasing lubricity and improving fast hole drilling.
The compositions of the invention, in their most preferred form, are believed to have the following general molecular structure:
wherein R
1
is distilled tall oil or coconut oil; R
2
is low rosin tall oil, vegetable oil or distilled tall oil; and R
3
is vegetable oil, tall oil or distilled tall oil.
A method is disclosed herein for producing the lubricant composition of the invention by combining and reacting the components within a controlled temperature range over a prolonged period and distilling off water and volatile reaction byproducts. The reaction and distillation can be done under pressures such as 45 to 120 psig using an autoclave or other pressure vessel in combination with a conventional overhead condenser system, or can be done at approximately atmospheric pressure (slight vacuum to 5 psig) using a conventional stirred reactor vessel that is vented to a condenser or to another chilled vessel that functions as a condenser.
According to a preferred method of the invention, the preferred components are combined and mixed inside a stirred reactor vessel in fluid communication with a chilled condenser section. The temperature of the reactants is gradually raised to a temperature above 300° F., most preferably between about 320° and about 350° F., using heating means such as steam coils, and maintained at that temperature, usually for about 6 to 8 hours or more, sometimes up to about 12 hours, until the reaction is substantially complete. Distillation is desirably continued until the pressure of reaction reaches zero to facilitate the removal of distillable liquids, sweet perfume and clear liquids, followed by dark distillates of rearrangement.
The reaction product is periodically sampled and the acid number is determined. Sampling is desirably continued on an hourly basis until the acid number is less than about 35, and most preferably, about 25 or lower. Samples are also desirably checked for AEW, which is preferably greater than 1000, and most preferably, ranges between about 2000 and about 5000 as the acid number drops to about 25.
The preferred amides for use in the invention are most preferably made using diethanolamine (DEA), monoethanolamine (MEA), and other hydroxyethylamines that can undergo low temperature esterification and then interchange during the distillation. The oils can react by inter- or trans-esterification. During the process of the invention, the oils, fatty acids or methyl esters are believed to further react with free amine, the amine portion of fatty ester components, and also, the glycerin produced by decomposition of the oils (triglycerides). The subject process is believed to facilitate molecular rearrangement, lower the acid number, increase the amine equivalent weight (AEW), and remove substantially all soaps, water, methanol and low molecular acids and unreacted esters from the product, together with any other species that will steam distill. Removal of the steam-distillable materials eliminates their subsequent vaporization during use, for example, in hot drilling systems.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The products of the invention utilize fatty acids, preferably fatty acids contained in tall oil derived from pine trees, containing about two weight percent rosin, and most preferably, distilled tall oil containing from about 10 to 50% rosin acids. Secondly, the products depend on other vegetable oils or extracts, especially those obtained from coconut or coffee, but can also be made using oils or extracts from soya, safflower, canola, rapeseed, flax, cotton and the like. Distilled tall oil, low rosin tall oil and reclaimed cooking oil can also be used as the “vegetable oil” component in making the compositions of the invention. Tall oil fatty acids having from 8 to 24 carbon atoms are preferred, with tall oil fatty acids having C
12
, C
14
, C
16
, C
18
and C
20
fatty acids being most preferred.
The mixing and prolonged heating of the reactants within a controlled temperature range and under distill
Locke Liddell & Sapp LLP
Ross Monty L.
Toomer Cephia D.
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