Hydraulic fracturing methods using cross-linking composition comprising delay agent

a technology of delay agent and cross-linking composition, which is applied in the direction of fluid removal, chemistry apparatus and processes, and wellbore/well accessories, etc., can solve the problems of limited number of disclosed delay agents, uneconomic recovery, and production rate decline, and achieve the effect of delaying the action

Inactive Publication Date: 2007-08-16
EI DU PONT DE NEMOURS & CO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0010] The present invention provides methods for effective delaying the action of titanium and zirconium cross-linking agents in oil field applications. Surprisingly, a range of temperature, pH and other conditions can be tolerated and delay times controlled to provide flexibility by adjusting relative amounts of components, including cross-linking agent and delay agents.

Problems solved by technology

Normally, less than one third of available oil is extracted from a well after it has been fractured before production rates decrease to a point at which recovery becomes uneconomical.
Ideally, such techniques (commonly called flooding techniques) provide a bank of oil of substantial depth being driven into a producing well; however, in practice this is frequently not the case.
Rather than developing new cross-linking agents for these new conditions, the oil well service companies may add delay agents that effectively delay the cross-linking of a particular metal cross-linking agent under these conditions.
There are only a limited number of disclosed delay agents suitable for titanium and zirconium cross-linking agents.
Thus, use of delay agents with titanium and zirconium cross-linking agents has limited flexibility for use by the oil well service companies to stimulate or enhance recovery of oil or gas from a well or other subterranean formation.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0056] Sodium chloroacetate (237 g) was added to 422 g of tap water in a 2-liter flask equipped with a dropping funnel, thermocouple, condenser and nitrogen bubbler. Agitation was started and heat applied to dissolve the sodium chloroacetate. After the sodium chloroacetate dissolved, 218 g of diethanolamine (99%) were added, and the reaction mass heated to reflux and held there for 10 hours. On cooling the solution was diluted with 510 g of water to give a clear, water white solution containing 24% bishydroxyethylglycine. The product of Example 1 was evaluated as a delay agent with each of the products of Examples 2-5 and Comparative Example D.

example 2

[0057] A 500-ml flask, equipped with a thermocouple, dropping funnel, nitrogen bleed and condenser, was charged with 313.7 g of zirconium tetra-triethanolamine complex, available from E. I. du Pont de Nemours and Company, Wilmington, Del. Agitation was started and a mixture of 20.9 g of glycerol and 20.9 g of water were added. The solution was agitated for 2 hours at 60° C. to give 355 g of an orange solution containing 11.6% Zr. Table 1A provides results using the product of Example 2 in the Vortex Closure Test.

example 3

[0058] A 500-ml flask, equipped with a thermocouple, dropping funnel, nitrogen bleed and condenser, was charged with 313.7 g of zirconium tetra-triethanolamine complex. Agitation was started and the following were added: 132.6 g of Quadrol® tetrakis(2-hydroxypropyl)ethylenediamine, available from BASF Corp., and a mixture of 42 g of glycerol and 42 g of water. The solution was agitated for 2 hours at 60° C. to give 530 g of an orange solution containing 7.8% Zr. Table 1B provides results using the product of Example 3 in the Vortex Closure Test.

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PUM

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Abstract

A method for hydraulically fracturing a subterranean formation comprises introducing into the formation a cross-linking composition which comprises (a) an aqueous liquid, (b) a pH buffer, (c) a cross-linkable organic polymer, (d) a cross-linking agent which comprises an organic titanate, an organic zirconate, or combinations thereof, and (e) a delay agent which is a hydroxyalkylaminocarboxylic acid. The method can be used over a wide range of pH conditions.

Description

FIELD OF THE INVENTION [0001] The invention relates to the field of oil well fracturing using a cross-linking composition. The cross-linking composition comprises a cross-linking agent which is a zirconium or titanium complex or mixtures thereof, a cross-linkable organic polymer and a delay agent. BACKGROUND OF THE INVENTION [0002] The production of oil and natural gas from an underground well (subterranean formation) can be stimulated by a technique called hydraulic fracturing, in which a viscous fluid composition (fracturing fluid) containing a suspended proppant (e.g., sand, bauxite) is introduced into an oil or gas well via a conduit, such as tubing or casing, at a flow rate and a pressure which create, reopen and / or extend a fracture into the oil- or gas-containing formation. The proppant is carried into the fracture by the fluid composition and prevents closure of the formation after pressure is released. Leak-off of the fluid composition into the formation is limited by the f...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): E21B43/26
CPCC09K8/685
Inventor PUTZIG, DONALD EDWARD
Owner EI DU PONT DE NEMOURS & CO
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