Earth boring – well treating – and oil field chemistry – Earth boring – Contains organic component
Reexamination Certificate
2000-11-14
2002-09-17
Tucker, Philip (Department: 1712)
Earth boring, well treating, and oil field chemistry
Earth boring
Contains organic component
C507S111000, C507S112000, C507S113000, C507S114000, C507S115000, C507S119000, C507S123000, C507S136000, C507S139000, C507S209000, C507S211000, C507S212000, C507S213000, C507S214000, C507S215000, C507S216000, C507S217000, C507S224000, C507S229000, C507S261000, C507S266000
Reexamination Certificate
active
06451743
ABSTRACT:
This invention relates to novel liquid suspension compositions, which can be used as additives in a water-based fluids, and methods of making and use of such liquid suspension compositions.
BACKGROUND OF THE INVENTION
Water-based fluids such as, for example, drilling fluids and mining fluids, are useful in a variety of industrial applications. It is well known to those skilled in the art of drilling wells to tap subterranean deposits of natural resources such as gas, geothermal steam or crude oil, especially when drilling by the rotary method or the percussion method wherein cuttings must be removed from the bore hole, that it is necessary to use a drilling fluid.
The use of water-based fluids in stimulation, workover and completion fluids in oil field operations is also well known. Workover fluids are those fluids used during remedial work in a drilled well. Completion fluids are those fluids used during drilling and during the steps of completion of the well.
Additives, chemicals, or other materials are often added to such water-based fluids for various reasons such as for controlling water loss, increasing viscosity, reducing corrosion, altering pH, and increasing density of the fluids. However, the addition of such materials to water-based fluids can be difficult unless proper precautions are taken to preclude agglomeration or plugging.
Liquid additives and processes therefor have been developed to overcome some of the problems. However, the hydrocarbons and other compounds used as the liquid medium of such stable liquid additive suspensions may not be environmentally friendly; because, they are often not biodegradable or because their use in drilling and well treatment fluids may result in noncompliance with EPA oil and grease effluent limitations.
It is, therefore, highly desirable to develop a liquid suspension composition which remains stable, useable as an additive in water or water-based fluids, and which is environmentally friendly for use in oil field applications.
SUMMARY OF THE INVENTION
It is thus an object of this invention to provide a stable liquid suspension composition which is environmentally friendly and useful in oil field applications.
Other aspects, objects, and the several advantages of the invention will become more apparent in light of the following disclosure.
According to a first embodiment of the invention, a stable liquid non-aqueous liquid suspension is provided. The non-aqueous suspension composition comprises non-soluble particles that are dispersed in a non-aqueous liquid medium. The non-aqueous medium has a concentration of a suspension aid. The non-aqueous liquid medium is selected from the group consisting of glycols, polyglycols, glycol ethers, glycol esters and glycol ether esters. The suspension aid is selected from the group consisting of hydroxypropyl cellulose, ethyl cellulose, polyvinyl pyrrolidone, polyacrylic acid, and copolymers of polyvinyl pyrrolidone and acrylic acid.
In a second embodiment of the invention, a non-aqueous suspension is prepared by mixing non-soluble particles, a suspension aid, and a liquid medium to thereby form the non-aqueous suspension. The liquid medium is selected from the group consisting of glycols, polyglycols, glycol ethers, glycol esters and glycol ether esters.
According to a third embodiment of the invention, a method is provided for treating oil or gas wells or any of the surrounding subterranean formations adjacent to such oil or gas wells. This method comprises the steps of admixing with a water-based fluid a composition comprising non-soluble particles dispersed in a non-aqueous liquid medium having a concentration of a suspension aid. The non-aqueous liquid medium is selected from the group consisting of glycols, polyglycols, glycol ethers, glycol esters and glycol ether esters. The suspension aid is selected from the group consisting of hydroxypropyl cellulose, ethyl cellulose, polyvinyl pyrrolidone, polyacrylic acid, and copolymers of polyvinyl pyrrolidone and acrylic acid. The thus-formed admixture is introduced into a wellbore.
DETAILED DESCRIPTION OF THE INVENTION
In accordance with the present invention, the novel non-aqueous suspension medium comprises, consisting essentially of, or consists of a non-aqueous liquid medium having dissolved therein a concentration of a suspension aid and having dispersed in such liquid medium non-soluble particles. The non-aqueous liquid suspension may also be described as comprising, consisting essentially of, or consisting of a liquid medium, non-soluble particles, and a stabilizing amount of a suspension aid sufficient to enhance the stability of the suspension of non-soluble particles in the liquid medium.
As referred to herein, the term “non-aqueous” means, unless otherwise indicated, a liquid that contains a minor amount of water, but, preferably, the liquid is one that is substantially free of water. The minor amount of water in the non-aqueous suspension medium is a concentration of water that is low enough to assure that the inventive non-aqueous suspension maintains the fluid properties of a stable suspension. A minor amount of water is generally less than about ten weight percent (10%) of the non-aqueous liquid medium. Thus, a minor amount of water will be in the range upwardly to about ten weight percent (10%). As noted, it is preferred for the non-aqueous liquid of the invention to be substantially free of water. Therefore, the non-aqueous liquid medium of the invention can have less than about one weight percent (1%) water, preferably, the amount of water is less than about 0.5 weight percent, and, most preferably, the amount of water is less than 1000 parts per million by weight (ppmw).
An important aspect of this invention is for the non-aqueous liquid medium to be an environmentally friendly compound. That is, a compound that is readily biodegradable when exposed to the environment and which passes the so-called oil and grease test by not being extractable from water by use of the extraction solvents as described in EPA Method 413.1 and EPA Method 1664.
Any suitable material that is in the liquid phase at ambient conditions, typically at temperatures between −30° C. to 50° C., preferably, between −20° C. to 40° C., and meets the above described criteria can be used as the non-aqueous liquid medium of the suspension composition of the invention so long as it forms a stable liquid suspension of the non-soluble particles when combined with the non-soluble particles and the suspension aid. The non-soluble particles and suspension aid are more fully defined elsewhere herein. Among the non-aqueous liquid medium compounds are those chemical compounds selected from the group consisting of glycols, polyglycols, glycol ethers, glycol esters and glycol ether esters.
Each glycol or polyglycol compound suitable for use as the non-aqueous liquid medium of the invention should have a molecular weight greater than about 100; because, those compounds that have molecular weights below about 100 tend to undesirably solvate the suspended particles. However, due to the requirement that the non-aqueous liquid medium be in the liquid phase at ambient temperatures, its molecular weight should be less than about 4,000. Therefore, suitable glycols and polyglycols can have a molecular weight in the range of from about 100 to about 4,000, preferably from about 100 to about 3,000, and more preferably, from about 100 to 2,750.
The glycols that can be used as the non-aqueous medium have the following general formula:
H—O—R
1
—O—H
where R
1
, is an alkyl group having from 4 to 8 carbon atoms, preferably, from 3 to 4 carbon atoms. Examples of suitable glycols include butylene glycol, 1,5-pentanediol and hexylene glycol.
The polyglycols that can be used as the non-aqueous medium have the following formula:
H—[O—R
1
]
n
O—H
where R
1
is an alkyl group having from 1 to 6 carbon atoms, preferably, from 2 to 4 carbon atoms. Specific examples of polyglycols that can suitably be used include, but are not limited to, diethylene glycol, triethylene glyco
Chevron Phillips Chemical Company LP
Stewart Charles W.
Tucker Philip
LandOfFree
Stable liquid suspension compositions and method of making... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Stable liquid suspension compositions and method of making..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Stable liquid suspension compositions and method of making... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2837771