Method and apparatus for stimulating a subterranean formation using liquefied natural gas

Abstract

Liquefied natural gas is used as a fracturing fluid to stimulate production of hydrocarbons from and / or injectability of fluids into subterranean formations. Proppants may be blended with the LNG prior to pumping the liquefied natural gas into the well. Optionally, the liquefied natural gas is heated after it is pumped and before it is introduced into the subterranean formation.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This is the first application filed for the present invention. MICROFICHE APPENDIX [0002] Not applicable. FIELD OF THE INVENTION [0003] This invention generally relates to well fracturing and well stimulation operations, and, in particular, to a fracturing fluid and method of fracturing a subterranean formation to stimulate production of fluids from a well, or to improve permeability of the subterranean formation to facilitate injection of fluids into the well. BACKGROUND OF THE INVENTION [0004] Most subterranean formations used for producing oil and gas, coal bed methane, tar sands, oil shale, or shale gas formations require some form of stimulation to enhance hydrocarbon flow from the formations to make or keep them economically viable. Likewise, most subterranean formations used for fluid storage or disposal require some form of stimulation to enhance fluid flow into those formations. The fracturing of subterranean formations to stim...

AI Technical Summary

Benefits of technology

[0016] It is therefore an object of the invention to provide an inexpensive, universally available, environmentally compatible, recoverable fracturing fluid that is fully compatible with subterranean formations.

[0017] It is a further object of the invention to provide a method of stimulating production of a subterranean formation using an inexpensive, universally available, recoverable fracturing fluid that reduces fracturing completion time and does not delay the start of production or commercialization of hydrocarbons produced from the well.

[0021] The invention therefore provides a fracturing fluid and methods for fracturing wells that are fully compatible with subterranean formations. The fracturing fluids are universally available at a reasonable cost, are environmentally compatible, and are commercially recoverable after stimulation is completed. The invention also reduce time to production after stimulation because production can be commenced as soon as a fracturing closure operation is effected. The release of fracturing fluid can be effected at any desired rate to ensure that the stimulation treatment has a desirable and lasting affect.

Problems solved by technology

First, in many parts of the world the water required for these fluids is difficult and expensive to obtain.

Second, transfer and disposal of used aqueous fluids is problematic.

It is well understood that dumping used fracturing fluids laden with chemical treatments and hydrocarbons into the sea is not an environmentally sound practice.

In most land jurisdictions the fluids must be disposed of in deep underground formations, which is expensive and may have unpredictable environmental consequences.

Third, aqueous fluids are by nature incompatible with most hydrocarbons and many subterranean formation compositions.

The mixing of aqueous fracture fluids with oil production is also undesirable, so fracturing fluids must be “flowed back” from a fractured well, separated from the oil and gas, and then disposed of in some way.

There is inevitable loss of hydrocarbons during the flow back, separation, and transportation, which all results in a loss of time before commercialization of the produced products can begin.

In addition, aqueous fracturing fluids can have deleterious effects on certain strata, such as clay stratum for example.

This adds expense and makes the fracturing fluid corrosive.

Furthermore, aqueous fluids used for fracturing introduce different ions, and elements into the subterranean formations which often results in scale formation on production equipment after the stimulation treatment.

The aqueous fluid fracturing fluids also present other environmental risks.

Besides, the injection of aqueous fluids into a coal bed methane strata can contaminate the potable water supply, entrain oxygen and air, stimulate bacterial growth, and induce the production of hydrogen sulfide in the strata.

If refined fluids such as ethanol or diesel are used, they are generally dissolved in the oils produced from the well, and / or contaminated by chemicals used in the fracturing process, and cannot be readily recovered for re-use or commercialization.

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