Earth boring – well treating – and oil field chemistry – Preventing contaminant deposits in petroleum oil conduits
Reexamination Certificate
2000-09-28
2003-10-07
Tucker, Philip (Department: 1712)
Earth boring, well treating, and oil field chemistry
Preventing contaminant deposits in petroleum oil conduits
C507S261000, C507S265000, C507S267000, C507S929000, C507S930000, C507S931000, C166S311000, C166S312000, C510S188000, C510S362000, C510S364000, C510S365000, C208S04800Q, C208S0480AA, C134S039000, C134S040000
Reexamination Certificate
active
06630428
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to the use of high flash point, low vapor pressure compositions for injection into, and coating of, gas and oil wells and surrounding underground formations and processing equipment for the purpose of removing scale, paraffins, tars, and other viscous constituents. Treatment results in increased flow of gas and/or oil and decreased adhesion of soils and scale in all aspects of oil and gas recovery, including formations, casing perforations, casings, lines, tanks, and pumping equipment.
BACKGROUND OF THE INVENTION
The efficient recovery of oil and gas from wells depends on maintaining clean formations, casing perforations, lines and pumping equipment. Oil wells have a problem with the build up of paraffin, sulfur, scale, heavy oil, and tar by-products. These residues foul the wells and the casing perforations and the lines that carry the oil or gas to the surface, and foul the pumps and metal rods which are used to recover the oil or gas from the well.
Typical prior art methods consist of four major types of products. The first method uses aggressive blends of aromatic and/or aliphatic petroleum hydrocarbons or halogenated hydrocarbons. These products may or may not contain surfactants to allow the products to mix with and emulsify in water to increase cleaning efficiency. The presence of water decreases the efficiency of these compositions significantly. Pure solvent blends are immiscible in water and cannot penetrate to the soils. The addition of emulsifiers allows the solvents to blend with the water, but the resulting solvent/emulsion system is not as efficient a cleaner as the pure solvent.
The second method is the use of bacteria to digest the paraffinic and tar-based soils. This system is very dependent on well temperature and is sensitive to environmental factors such as the composition of the oil. This process is typically slower than the solvent-based process.
The third method is predicated on water-based alkaline, hard-surface cleaners. These cleaners generally incorporate alkaline builders, water-soluble solvents, such as glycol ethers, alcohols, and surfactants. Alkaline builders consist of hydroxide, carbonate, phosphate, and silicate. Water-soluble solvents typically consist of ethylene glycol, diethylene glycol, propylene glycol and dipropylene glycol ethers. Typical surfactants are the categories of alkyl phenol ethoxylates, linear alcohol ethoxylates, or alkyl sulfonates, amphoterics, and fatty acid soaps of alkanolamides. The cleaning efficiency of these alkaline compositions on paraffins and other oil-based soils is typically much lower than that of solvent blends. Further, these compositions are not effective for removing scale.
The fourth method of cleaning involves the use of hot oil, which is injected into the well. The hot oil melts and dissolves the paraffins and other oil byproducts and carries them to the surface. Although this method is efficient, the use of hot oil creates a hazardous condition and can adversely affect the wells.
Typical prior art compositions employ solvents of aromatic and/or aliphatic petroleum hydrocarbons or halogenated hydrocarbons. These solvents produce vapor emissions, commonly known as “VOCs” (volatile organic compounds), which typically are toxic. Other cleaning compositions require little or no VOCs, but require high levels of caustic and/or phosphates which cause problems in transportation, use, and disposal.
There are many problems associated with the above-mentioned methods and solvents. For example, halogenated hydrocarbons affect worker health adversely and are ozone-depleting chemicals. Some of the solvents and methods may adversely affect the quality of the oil or gas. Many of the non-halogenated solvents used are either flammable or combustible, resulting in increased fire and explosion risks and higher insurance premiums. Furthermore, the disposal of the spent solvents, in accordance with government regulations, is expensive. In fact, most of the halogenated solvents are subject to high taxes and are in the process of being phased out. In addition to the above-mentioned problems, limits on the amount of VOCs that may be emitted into the atmosphere are set by the Environmental protection Agency, as specified by the “Clean Air Act.” These limits are determined by the solvent content of the incoming production of raw material versus the solvent content of the waste or finished products.
The bacteria-based cleaning solution also has other disadvantages. The treatment requires that the well be shut down for two weeks to allow the establishment of a bacterial colony. When pumping is resumed, the bacteria are removed with the oil, which results in rapid depletion of the colony and retreatment is required.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method of cleaning gas and oil wells, equipment, well casing perforations, and surrounding formations, pumps, as well as lines, pipes, and the like using an effective cleaning composition which is free of objectionable petroleum-derived or halogenated hydrocarbon and alkaline solvents and useful in removing most of the soils and scale encountered in gas- and oil-well cleaning operations.
Another object is to use a composition which is safe and biodegradable.
A further object is to use a composition capable of functioning at ambient temperatures and at elevated temperatures.
A further object is to use a safe liquid cleaning composition containing fatty acid methyl esters and lower alkyl glycol ethers, which is effective in removing paraffins, tars, related soils, and scale from gas- and oil-wells, casings and equipment.
An additional object is to use a low VOC composition (<50%), which is effective as a cleaner for gas- and oil-wells, casings and equipment.
An additional object of the invention is to use a composition with a flash point above 200° F.
A further object is to use a composition which will 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.
An additional object is to provide a composition which is low evaporative, widely dispersive, and results in differential wetting of well structures and equipment.
An additional object is to provide enhanced gas and oil recovery from wells.
A further object is a method to separate excess water from recovered crude petroleum oil.
The present invention is directed to a method for removing and preventing the buildup of soils, scale, or both, from gas or oil wells, hydrocarbon bearing formations, and recovery, pumping, storage, and transmission equipment, comprising introducing into said well, formation or equipment a composition comprising about 40 to 99 wt % of a fatty acid alkyl ester blend and about 1 to 25 wt % of at least one lower alkyl glycol ether.
The present invention is also directed to a method for separating excess water, sludge, or both, from recovered crude petroleum oil comprising adding to the crude petroleum oil a composition comprising about 40 to 99 wt % of a fatty acid alkyl ester blend and about 1 to 25 wt % of at least one lower alkyl glycol ether, and then agitating the mixture.
In addition, the present invention provides an improved fracing process of forcing sand and/or another granular material into an oil or gas formation under pressure, whereby the improvement comprises mixing the sand with a composition comprising about 40 to 99 wt % of a fatty acid allyl ester blend and about 1 to 25 wt % of at least one lower alkyl glycol ether.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The most common industrial uses of fatty acid alkyl ester blends are as industrial metal working lubricants, in soap manufacturing, as a plasticizer for waxes and as solvents in the formulation of industrial oils and leather treating compounds. These compounds are also used as textile lubricants and foam depressan
Cioletti Kenneth R.
Furman Harvey A.
Rzucidlo Eugene C.
Tucker Philip
United Energy Corporation
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