Fracturing fluid composition and method of using same in geological formations

Abstract

A composition and method required for providing a fracturing fluid pumped down a well bore and into a subterranean formation under conditions of pressure that will fracture the subterranean formation is described. More specifically, the composition increases the recovery of hydrocarbons from a geological formation penetrated by a well bore, wherein the composition includes a fracturing fluid that is liquid carbon dioxide (LCO₂) with proppant to aid transport of the proppant in suspension, and thereby create a fracture using a fracturing fluid which is the thickened composition containing fumed silica. When the composition is without a proppant, the viscosity of the composition is increased in order to improve the fracturing operation through aspects such as increased fracture width and reduced fluid leak-off

Description

[0001]The present application claims priority from U.S. Provisional Application Ser. No. 61 / 837,974, filed Jun. 21, 2013, which is incorporated by reference herein in its entirety.FIELD OF INVENTION[0002]The present invention relates to a fracturing fluid and optionally an associated proppant composition wherein fumed silica increases the viscosity of liquid carbon dioxide that is delivered into a well-bore for the fracture treatment of oil and gas reservoirs.BACKGROUND OF THE INVENTION[0003]The use of carbon dioxide for production of oil and gas from hydrocarbon containing reservoirs is well known. Utilization of liquid carbon dioxide (LCO2) in fracture treatment of oil and gas formations has certain advantages in water sensitive and low pressure formations. First, the use of LCO2 enables a significant reduction in water volume utilized, which minimizes formation damage caused by the water and second, it promotes water flow-back (i.e., retrieval of water introduced, or produced, in...

AI Technical Summary

Benefits of technology

[0011]The present invention provides a fluid composition for increasing the recovery of hydrocarbons from a geological formation, wherein the fluid composition includes: a non-polar fluid that is liquid carbon dioxide (LCO2) and a fumed silica thickener, wherein the thickener increases the viscosity of the fluid composition to a range of between about 0.5 to 500 centipoise.

[0012]The invention also includes providing a method of fracturing, wherein the fluid is pumped down a well bore and into a subterranean formation (e.g., containing oil, gas, hydrocarbons, etc.) at a pressure that will fracture the subterranean formation. It is one object of the present invention to provide a fracturing fluid which will have sufficient viscosity to operate effectively. More specifically, the present invention provides a composition as well as a method for providing the fluid composition which increases the productivity of hydrocarbon extraction from a geological formation penetrated by a well. The composition includes a fracturing fluid that is liquid carbon dioxide (LCO2), and a fumed silica which increases the viscosity of the composition. This thickener enhances the fracturing of the formation and placement of proppant depending on the geological formation and the composition of the strata that is being extracted.

[0013]It is also an object of the present invention to produce a fluid composition that behaves as a shear thinning or thixotropic fluid with a viscosity that will decrease with increasing shear rates. This will cause the apparent viscosity to drop in the vicinity of the well bore where shear stresses are high, and thereby minimize frictional losses. This will cause the apparent viscosity to increase in the fracture where shear stresses are lower, so that proppant can be delivered throughout the fracture.

[0014]It is yet another object of this invention to produce a fluid which is not permanently degraded by the extremely high rates of shear, pressures, and temperatures encountered during the hydraulic fracturing processes. The fracturing fluid may also include a hydrocarbon, a surfactant, a polymer (e.g., gelling agent, friction reducer, etc.) and / or minor polar compound, or a mixture of these components, normally in the absence of any water or moisture. The fluid also contains a thickening or viscosity increasing agent comprising fumed silica with a surface area of from 50 to 400 m2 / g and an average primary particle size from 7 to 40 nanometers. The goal is to use the fumed silica to increase the viscosity by at least five fold using approximately 1,000-10,000 ppm of the fumed silica (up to 1 percent by weight is likely) and thereby minimize the cost associated with fracturing operations utilizing the fumed silica. The fracturing fluid is substantially devoid of any water or moisture, as it “contaminates” the fluid composition. The possibility of water and moisture addition, however, exists in most cases such as in this embodiment, but it is undesirable.

Problems solved by technology

The possibility of water and moisture addition, however, exists in most cases such as in this embodiment, but it is undesirable.

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