Earth boring – well treating – and oil field chemistry – Earth boring – Contains organic component
Reexamination Certificate
2000-09-12
2003-02-04
Tucker, Philip (Department: 1712)
Earth boring, well treating, and oil field chemistry
Earth boring
Contains organic component
C507S126000, C507S207000, C507S232000, C507S904000, C507S922000, C175S072000
Reexamination Certificate
active
06514916
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to the production of drilling fluids for oil and gas exploration and production operations. Specifically, the present invention relates to the sulfonation of uintaite and the application of sulfonated uintaite to oil and gas well drilling fluids, oil and gas well completion fluids, and fluid loss control of hydraulic fracturing fluids for oil and gas wells.
BACKGROUND OF THE INVENTION
It is well known that in penetrating the earthen formations to tap subterranean deposits, such as gas or oil, that penetration is accomplished by well drilling tools and a drilling fluid. Drilling fluid, also commonly known as drilling mud, serves to cool and lubricate the drill bits, to carry the cuttings to the surface as the drilling fluid is circulated in and out of the well, to support at least part of the weight of the drill pipe and drill bit, to provide a hydrostatic pressure head to prevent caving of the walls of the well bore, to deposit on the surface of the well bore a filter cake which acts as a thin, semi-impervious layer to prevent undue passage therethrough of drilling fluids, and to perform other functions as are well known in the drilling art. These fluids must be capable of exhibiting some rather sophisticated performance characteristics such as inhibiting the disintegration of drill cuttings, protecting and/or stopping the sloughing of unstable hard and brittle shales, have lubricating characteristics, reducing fluid loss, and particularly reducing high temperature fluid losses of drilling fluids, and reducing the fluid losses and spurt losses of hydraulic fracturing fluids during the hydraulic fracturing process. Furthermore, the prepared fluids must exhibit a viscosity in both brine waters and fresh waters and in selected oils sufficiently low to allow pumping.
It is also important that the drilling fluid exhibit a relatively low rate of filtration or fluid loss. That is, the drilling fluid should permit little, if any, loss of its liquid phase to the formation penetrated, as is well known to those skilled in the art. Most drilling fluids contain additives and conditioning agents which are important in determining the fluid loss properties of the drilling fluid, as well as inhibiting shale and clay disintegration.
In addition to exhibiting a low rate of fluid loss, it is desirable for the fluid to have certain rheological properties, such as low viscosity and gel strength.
One material known to be effective in drilling fluid is sulfonated asphalt. Sulfonated asphalt marketed under the trademark “Soltex®” by Phillips Petroleum Company has been used as a drilling fluid for many years. Six patents assigned to Phillips Petroleum Company relating to the production of sulfonated asphalt are: Stratton, et al., U.S. Pat. No. 3,028,333; Stratton, et al., U.S. Pat. No. 3,089,842; Pitchford, et al., U.S. Pat. No. 3,089,846; Peacock, et al., U.S. Pat. No. 3,215,628; and, Clampitt, et al., U.S. Pat. No. 4,514,308, incorporated herein by reference. Although sulfonated asphalt has many desirable properties, there still remains a need for a more effective product.
Known problems exist when sulfonating asphalt in the process of production of drilling fluids. A main problem resides with the characteristics of asphalt itself. The softening point of typical conventional refinery asphalts is approximately 130° to 155° F. In the production of sulfonated asphalt, the drying temperature is higher, 190° to 400° F., thus causing the non-sulfonated asphalt to be very sticky in the production equipment. In order to avoid this, the drying time must be extended at lower temperatures, resulting in a slow rate of drying. Longer drying times mean lower throughput in the manufacturing process. Moreover, the minimum level of sulfonation of the asphalt is dictated by properties required for smooth mechanical operations during the drying process If the level of sulfonation is too low, the product remains “gummy” and sticks to metal surfaces in rotary type dryers at the above temperatures to an extent that makes the process mechanically unworkable. When mechanical rotary dryers are used, the production rate is very much limited to low levels of sulfonation when using asphalts from conventional rude oil type refineries. Also, asphalt must be transported in heated trucks causing difficult handling, storage and heat maintenance problems. A need, therefore, exists for a material which can be efficiently produced at advantageous levels of sulfonation also manufactured without sticking to the production equipment and transported without heating.
Uintaite is a naturally occurring hydrocarbon mineral that was discovered in the early 1860's in the Uintah Basin in northeastern Utah. It occurs in vertical veins outcropping on the surface and extends downward hundreds of feet. The vertical veins are usually two to six feet wide, and veins as wide as 13 to 20 feet have been discovered and mined. The veins are nearly parallel to each other and are oriented in a northwest to southeast direction. They extend many miles in length and are as deep as 1500 to 2000 feet. Uintaite is mined with modern equipment such as with pneumatic chipping hammers and with mechanical and air hoists. Samuel H. Gibson began to promote the use of uintaite in the mid-1880s as a waterproof coating material for wooden pilings, and as insulation for wire cable and as a unique varnish.
Uintaite is a natural product whose chemical and physical properties vary and depend strongly on the uintaite source. Although uintaite is sometimes loosely described as an asphaltic material, its composition varies greatly from asphalt derived from refining operations. Uintaite is known to have the following characteristics: (1) high asphaltene content; (2) high solubility in organic solvents; (3) high purity and consistent properties; (4) high molecular weight; and, (5) high nitrogen content. One typical general analysis of uintaite shows the following weight percentages: Carbon 84.9%, Hydrogen 10.0%, Nitrogen 3.3%, Sulfur 0.3%, Oxygen 1.4%, Trace Elements 0.1%. Uintaite has a molecular weight of about 3000 which is considered very high compared to asphalt products from conventional crude oil refineries.
Uintaite is also commonly called “gilsonite” although this term is believed to be a registered trademark of American Gilsonite Company, Salt Lake City, Utah (Reg. No. 0144,545). Three different companies in the US mine and sell today the naturally occurring mineral uintaite in the form of several softening point ranges. Upon information and belief, all three companies advertise their products as Gilsonite. These three companies are American Gilsonite Company with a corporate address of 109 Stevenson Street, Third Floor; San Francisco, Calif. 94105; LEXCO, INC.; P.O. Box 1198 of Vernal, Utah 84078; and the Ziegler Chemical and Mineral Corporation of 600 Prospect Avenue, Piscataway, N.J. 08854.
Typical uintaite used in drilling fluids is mined from an area around Bonanza, Utah and has a specific gravity of 1.05 with a softening point ranging from 325 deg. F to as high as 400+ deg. F. The lowest softening point material is used less frequently in drilling fluids. Uintaite has a low acid value, a zero iodine number, and is soluble or partially soluble in aromatic and aliphatic hydrocarbons, respectively. It is generally processed and ground to where 99% passes through a 65-mesh Tyler screen with approximately 3% being retained on a 100-mesh screen and 16% on a 200-mesh screen, non-cumulative. Uintaite is very friable so size reduction is easy with minimum equipment required.
American Gilsonite Company sells a variety of Gilsonite resins, sometimes identified by their softening points (Ring and Ball, an ASTM Method). For example, general purpose (GP) uintaite brand resin has a softening point of about 350 deg. F, and uintaite HM has a softening point of about 380 deg. F, and uintaite Select 300 and Select 325 which have softening points of 300 and 325 deg. F, respectively. The softening points of these naturally derived
Clampitt Richard L.
Swanson Billy L.
Fellers Snider Blankenship Bailey & Tippens, P.C.
R. L. Clampitt & Associates, Inc.
Tucker Philip
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