Methods of treating subterranean formations using low-temperature fluids

Abstract

Methods for treating subterranean formations using low-temperature fluids are provided. An example of a method is a method of treating a subterranean formation. Another example of a method is a method of fracturing a subterranean formation. Another example of a method is a method of producing hydrocarbons from a subterranean formation.

Description

BACKGROUND [0001] The present invention relates to methods useful in subterranean treatment operations. More particularly, the present invention relates to methods for treating subterranean formations using low-temperature fluids. [0002] Hydrocarbon-bearing subterranean formations penetrated by well bores often may be treated to increase their permeability or conductivity, and thereby facilitate greater hydrocarbon production therefrom. One such production stimulation treatment, known as “fracturing,” involves injecting a treatment fluid (e.g., a “fracturing fluid”) into a subterranean formation or zone at a rate and pressure sufficient to create or enhance at least one fracture therein. Conventional fracturing fluids commonly comprise a proppant material (e.g., sand, or other particulate material) suspended within the fracturing fluid, which proppant material may be deposited into the created fractures. The proppant material functions, inter alia, to prevent the formed fractures fr...

AI Technical Summary

Benefits of technology

[0006] The present invention relates to methods useful in subterranean treatment operations. More particularly, the present invention relates to methods for treating subterranean formations using a low-temperature fluid.

[0007] An example of a method of the present invention is a method of treating a subterranean formation comprising placing a low-temperature fluid in a subterranean formation so as to create or enhance at least one fracture therein, the low-temperature fluid having a temperature below the ambient temperature at the surface.

[0008] Another example of a method of the present invention is a method of fracturing a subterranean formation comprising: positioning a hydrojetting tool having at least one fluid jet forming...

Problems solved by technology

While the use of gelled and crosslinked polysaccharide-containing fracturing fluids has been successful, such fracturing fluids often have not been thermally stable at temperatures above about 200° F. That is, the viscosity of the highly viscous gelled and crosslinked fluids may decrease over time at high temperatures.

To offset the decreased viscosity, the concentration of the viscosifier often may be increased, which may result in, inter alia, increased costs and increased fiction pressure in the tubing through which the fracturing fluid is injected into a subterranean formation.

This may increase the difficulty of pumping the fracturing fluids.

However, the use of thermal stabilizers also may increase the cost of the fracturing fluids.

Certain types of subterranean formations, such as certain types of shales and coals, may respond unfavorably to fracturing with conventional fracturing fluids.

For example, in addition to opening a main, dominant fracture, the fracturing fluid may further invade numerous natural fractures (or “butts” and “cleats,” where the formation comprises coal) that may intersect the main fracture, which may cause conventional viscosifiers within the fracturing fluid to invade intersecting natural fractures.

When the natural fractures re-close at the conclusion of the fracturing operation, the conventional viscosifiers may become trapped therein, and may obstruct the flow of hydrocarbons from the natural fractures to the main fracture.

This may be problematic, inter alia, where the production of hydrocarbons from the subterranean formation involves processes such as desorption of the hydrocarbon from the surface of the formation.

However, this may be problematic, inter alia, because such fluids may prematurely dilate natural fractures perpendicular to the main fracture—a problem often referred to as “near well bore fracture complexity,” or “near well bore tortuosity.” This may be problematic because the creation of multiple fractures, as opposed to one or a few dominant fractures, may result in reduced penetration into the formation, e.g., for a given injection rate, many short fractures may be created rather than one, or a few, lengthy fracture(s).

This may be problematic because in low permeability formations, the driving factor to increase hydrocarbon production often is the fracture length.

Furthermore, the use of less viscous fracturing fluids also may require excessive fluid volumes, and / or excessive injection pressure.

Excessive injection pressure may frustrate attempts to place proppant material into the fracture, thereby reducing the likelihood that the fracturing operation will increase hydrocarbon production.

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