Methods of treating a subterranean formation with a treatment fluid having surfactant effective to increase the thermal stability of the fluid

a technology of hydrocarbonbearing subterranean formation and treatment fluid, which is applied in the direction of fluid removal, insulation, borehole/well accessories, etc., can solve the problems of subterranean formation rock that is subjected to hydraulic treatment literally cracking apart or breaking under strain, and fractures that tend to be squeezed closed

Inactive Publication Date: 2007-11-08
HALLIBURTON ENERGY SERVICES INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The invention provides methods for treating a subterranean formation penetrated by a wellbore with a treatment fluid that is thermally stabilized by a surfactant. The treatment fluid has a desired viscosity at a desired temperature for a desired time. The method involves using a treatment fluid that includes a base fluid, a viscosifying agent comprising a polymer, and a surfactant. The concentration of the surfactant in the treatment fluid is higher than what would be needed to achieve the desired viscosity without the polymer. The treatment fluid is introduced into the subterranean formation. The technical effect of the invention is to provide a more effective and efficient method for treating subterranean formations with a thermal treatment fluid.

Problems solved by technology

The higher temperatures can be a problem for the gels used in various treatments on a subterranean formation to improve the flow of hydrocarbon.
The fracturing fluid is injected through the wellbore at such a high flow rate and under such high pressure that the rock of the subterranean formation that is subjected to the hydraulic treatment literally cracks apart or fractures under the strain.
However, once the high pressure is relieved by the escape of the fracturing fluid through the created fracture and out further into the subterranean formation, the fracture has a tendency to be squeezed closed by the natural pressures on the rock within the deep subterranean formation.
The fines have a tendency to plug small pore spaces in the formation and block the flow of oil.
Moreover, the fines are highly abrasive and can be very harmful to pumping equipment.

Method used

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  • Methods of treating a subterranean formation with a treatment fluid having surfactant effective to increase the thermal stability of the fluid
  • Methods of treating a subterranean formation with a treatment fluid having surfactant effective to increase the thermal stability of the fluid
  • Methods of treating a subterranean formation with a treatment fluid having surfactant effective to increase the thermal stability of the fluid

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0066] In Example 1, Sample 1 was a borate-crosslinked HPG gel prepared without any of the surfactant blend, and Sample 2 contained 1 gal / Mgal of the surfactant blend.

[0067] Experiments on Samples 1 and 2 were conducted using a Nordman Model 50 viscometer according to a modified API2 test procedure as the sample was rapidly heated from room temperature to 240° F. in about 20 minutes and then held at 240° F. Viscosity was frequently measured at a shear rate of 81 / sec over a period of more than 3 hours.

[0068] The results of these experiments on Sample 1 and Sample 2 shown in the graph of FIG. 1 demonstrate an unexpectedly improved thermal stability of a borate crosslinked HPG gel with 1 gal / Mgal of the surfactant blend compared to an otherwise identical treatment fluid without any of the surfactant blend. In other words, the improved thermal stability is observed compared to an otherwise substantially identical treatment fluid without any of the surfactant.

example 2

[0069] In Example 2, experiments were conducted to study the effect of varying the concentration of the surfactant in the borate-crosslinked HPG gel. Sample 2 contained 1 gal / Mgal of the surfactant blend. Sample 3 contained 2 gal / Mgal of the surfactant blend. Sample 4 contained 3 gal / Mgal of the surfactant blend.

[0070] Experiments on Samples 2, 3, and 4 were conducted using a Nordman Model 50 viscometer according to a modified API2 test procedure as the sample was rapidly heated from room temperature to 285° F. (140° C.) in about 20 minutes and then held at 285° F. (140° C.). Viscosity was frequently measured at a shear rate of 81 / sec over a period of more than 3 hours.

[0071] The results shown in the graph of FIG. 2 demonstrate that increased surfactant concentrations unexpectedly improve the thermal stability of a borate-crosslinked HPG gel.

example 3

[0072] In this Example, four gel samples of the borate-crosslinked, 50 lb / Mgal HPG in 4% KCl water at a pH of about 10.5 were prepared containing varying amounts of the surfactant blend and sodium thiosulfate, as shown in Table 1:

TABLE 1Sample #Gal / Mgal surfactant blendLb / Mgal sodium thiosulfate500630701831

[0073] Samples 5, 6, 7, and 8 were evaluated on a Nordman Model 50 viscometer using a modified API2 test procedure as the sample was rapidly heated from room temperature to 285° F. (140° C.) in about 20 minutes and then held at 285° F. (140° C.). Viscosity was frequently measured at a shear rate of 81 / sec over a period of about 1.5 hours.

[0074] The results shown in the graph of FIG. 3 demonstrate an unexpected synergistic relationship between a surfactant and sodium thiosulfate for improving the thermal stability of a borate crosslinked HPG gel.

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Abstract

Methods of treating a subterranean formation penetrated by a wellbore are provided, the methods comprising the steps of: (a) for a treatment fluid to be used in treating a subterranean formation, establishing a desired viscosity at a desired temperature for a desired time; (b) forming a treatment fluid that has the desired viscosity at the desired temperature for the desired time, wherein the treatment fluid comprises: (i) a base fluid; (ii) a viscosifying agent comprising a polymer; and (iii) a surfactant; and (c) introducing the treatment fluid into a subterranean formation. According to one aspect, an otherwise substantially identical treatment fluid with a lower concentration of the surfactant would not achieve the desired viscosity at the desired temperature for the desired time. According to another aspect, the polymer is at a lower concentration in the base fluid than would be required for an otherwise substantially identical treatment fluid with a lower concentration of the surfactant to achieve the desired viscosity at the desired temperature for the desired time.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] Not Applicable. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT [0002] Not Applicable. REFERENCE TO A MICROFICHE APPENDIX [0003] Not applicable. TECHNICAL FIELD [0004] The invention generally relates to methods of treating a hydrocarbon-bearing subterranean formation with viscosified fluids for various purposes, such as gravel packing and hydraulic fracturing. Such treatment fluids are viscosified with polymeric materials that are sensitive to elevated temperatures. The invention relates to using a surfactant to increase the thermal stability of such viscosified treatment fluids. BACKGROUND [0005] Hydrocarbon (e.g. crude oil and natural gas) is used for making various grades of fuels and oils. Hydrocarbon is obtained from a hydrocarbon-bearing subterranean formation by drilling a wellbore into the earth, either on land or under the sea, that penetrates the hydrocarbon-bearing formation. Typically, such a wellbore must be...

Claims

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Application Information

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Patent Type & AuthorityApplications(United States)
IPC IPC(8): E21B43/24E21B43/22
CPCC09K8/602C09K8/68C09K8/90C09K8/887C09K8/685
InventorWELTON, THOMAS D.GRIFFIN, DAVID E.BARRICK, DAVID M.BRYANT, JASONTALBOT, MALCOM
OwnerHALLIBURTON ENERGY SERVICES INC