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Methods and compositions for treating subterranean formations using high ionic strength gelling agent polymers

a gelling agent and high ionic strength technology, applied in fluid removal, chemistry apparatus and processes, and wellbore/well accessories, etc., can solve the problems of less soluble hard water, less soluble carboxyl groups, and less salt sensitivity, so as to improve rheological properties and high ionic strength , the effect of high ionic strength

Inactive Publication Date: 2005-03-24
HALLIBURTON ENERGY SERVICES INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides improved methods for treating subterranean formations with viscous aqueous treating fluids. These methods involve using a high ionic strength gelling agent polymer, which is a sulfonated polymer that improves the viscosity of the treating fluid at pH's below 7 and in hard water. The improved methods involve preparing a viscous aqueous treating fluid composition by adding water and a high ionic strength gelling agent polymer to the subterranean formation. The technical effects of this invention include improved viscosity properties of the treating fluid and better rheological properties in challenging conditions.

Problems solved by technology

A problem is that the viscosity increasing effect of carboxyl groups is greatly reduced as the pH of the fluid drops below 7.
In addition, the solubility of anionic groups in water containing multivalent metal ions such as calcium and magnesium is small making gelling agent polymers containing anionic groups, e.g., carboxyl groups, less soluble in hard water.
The salt sensitivity is undesirable since the aqueous liquids used in well treating fluids often contain chloride salts to inhibit swelling of formation clays or are formed with brines or seawater.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0027] To demonstrate stability of sulfonated gelling agent polymers to potassium chloride the viscocity of a 0.5% solution of sulfonated guar polymer was compared to that of a 0.5% solution of carboxymethyl guar at 75° F. Viscosity measurements were made with increasing additions of potassium chloride.

[0028] The results are shown in Table 1 below. The viscosity of carboxymethyl guar decreases significantly with initial additions of potassium chloride. The sulfonated polymer basically maintains its viscosity.

TABLE 1Viscosity After KCl AdditionViscosity, cP% KClCMG*SULF*026.3428.70.2520.29—0.520.15—119.0827.3218.7526.3318.8225.5418.6924.8518.4924.2618.1923.6718.1423.2817.8922.9917.6822.31017.6522.21117.9022.51217.6122.6

*CMG = Carboxymethyl guar

*SULF = Sulfonated guar

example 2

[0029] To demonstrate the superior stability of sulfonated gelling agent polymers in the presence of divalent cations, a 0.5% solution of sulfonated guar polymer was compared to that of a 0.5% solution of carboxymethyl guar. Viscosity measurements were made at 75° F. with increasing additions of calcium chloride.

[0030] The results are shown in Table 2 below. The viscosity of carboxymethyl guar decreases significantly with initial additions of calcium chloride. The sulfonated polymer basically maintains its viscosity.

TABLE 2Viscosity After CaCl2 AdditionViscosity, cP% CaCl2CMG*SULF*024.428.90.12519.928.70.2519.528.90.5019.828.90.75—28.91.020.628.92.021.728.93.022.229.14.022.729.15.02329.06.02329.1102630.6

*CMG = Carboxymethyl guar

*SULF = Sulfonated guar

example 3

[0031] The thermal stability of a carboxymethyl guar treating solution was compared to a sulfonated guar polymer treating solution of this invention. The polymer solutions were prepared at a concentration of 0.5 weight percent in deionized water. In two of the tests, a gel stabilizing agent comprised of sodium thiosulfate, was added as indicated in Table 3 below. The polymer solutions were hydrated at pH 7 and the viscosities were measured at 75° F. The solutions were sparged with nitrogen and heated in a pressure vessel under 100 psi to 300° F. for 4 hours. The solutions were then cooled to 75° F. and the viscosities were measured again.

[0032] As shown in Table 3, the solutions of sulfonated guar polymer had superior thermal stability compare to the carboxymethyl guar.

TABLE 3Effect of Time and Temperature on ViscosityGelGellingStabilizingFinalAgentAgentlb / 1000Initial ViscosityViscositySamplePolymergalcP @ 75 F.cP @ 75 F.*% of Initial Viscosity*1CarboxymethylguarNone39.022.25.62C...

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Abstract

Methods, aqueous treating fluid compositions and high ionic strength gelling agent polymers for treating subterranean formations are provided. The aqueous treating fluid compositions are basically comprised of water and a high ionic strength sulfonated gelling agent polymer. The aqueous treating fluid compositions have superior properties compared to conventional treating fluids.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to methods, aqueous treating fluid compositions and high ionic strength gelling agent polymers for treating subterranean formations. [0003] 2. Description of the Prior Art [0004] Viscous treating fluids are used in a variety of operations and treatments in oil and gas wells. Such operations and treatments include forming gravel packs in well bores, fracturing producing zones, performing permeability control treatments and the like. [0005] Hydrocarbon producing wells are often stimulated by hydraulic fracturing treatments. In hydraulic fracturing, a viscous fracturing fluid, which also functions as a carrier fluid, is pumped into a subterranean zone to be fractured at a rate and pressure such that one or more fractures are formed in the zone. Proppant particles, e.g., graded sand, for propping the fractures open are suspended in the fracturing fluid and are deposited in the fractures whe...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C09K8/68E21B43/00
CPCC09K8/685C09K8/68
Inventor WEAVER, JIMMIE D.SLABAUGH, BILLY F.
Owner HALLIBURTON ENERGY SERVICES INC
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