Method of increasing fracture network complexity and conductivity

Abstract

A complex fracture network within a hydrocarbon-bearing subterranean formation is created by first pumping a first fluid into the formation to create or enlarge a primary fracture and then pumping a second fluid into the formation wherein the second fluid contains a viscous material and the first fluid. By diverting the flow of the second flow, a secondary fracture is created having a directional orientation distinct from the directional orientation of the primary fracture.

Description

[0001]This application claims the benefit of U.S. patent application 61 / 809,187, filed on Apr. 5, 2013, herein incorporated by reference.FIELD OF THE DISCLOSURE[0002]Fracture network complexity within a subterranean formation may be created by pumping a low viscosity fluid into the formation followed by a low viscosity fluid containing independent small masses of viscous material. Stimulated rock volume (SRV) of the formation is increased with the complex fracture network created in the formation.BACKGROUND OF THE DISCLOSURE[0003]Hydraulic fracturing is widely used to create high-conductivity communication with a large area of a subterranean formation, thereby allowing for an increased rate of oil and gas production. The stimulation process enhances the permeability of the formation in order that entrapped oil or gas may be produced.[0004]During hydraulic fracturing of ultra-low permeability formations (i.e. such as less than 0.1 md), a fracturing fluid is pumped at high pressures a...

AI Technical Summary

Benefits of technology

The patent text describes a method of fracturing a hydrocarbon-bearing subterranean formation by pumping two fluids into the formation. The first fluid creates or enlarges a primary fracture, while the second fluid creates one or more secondary fractures that have a distinct directional orientation from the primary fracture. These secondary fractures then create a complex fracture network, which can include multiple fractures that originate from the secondary fractures. The second fluid is made up of a viscous material and a discrete body added to the first fluid. The method can also involve creating a surface area ratio or conductivity ratio to measure the effectiveness of the fracturing process. The technical effects of this patent text include improved methods for fracturing hydrocarbon-bearing subterranean formations, which can increase the production of oil and gas from these formations.

Problems solved by technology

After the viscosity of the fluid has been reduced, complete removal of the polymer is often difficult, often times resulting in residual polymer being left on the face of the formation and within the proppant pack.

This causes clogging of the pores of the formation and proppant pack.

Slickwater fluids typically do not contain a viscoelastic surfactant or viscosifying polymer but do contain a sufficient amount of a friction reducing agent to minimize tubular friction pressures.

In some shale formations, an excessively long primary fracture often results along the minimum stress orientation.

In most instances, primary fractures dominate and secondary fractures are limited.

Production of hydrocarbons from the fracturing network created by such treatments is limited by the low SRV.

Slickwater fracturing more commonly in shale formations create complex fracture networks near the wellbore and are generally considered to be inefficient in the opening or creation of complex network of fractures farther away from the wellbore.

However, the secondary fractures created by the operation are near to the wellbore where the surface area is increased.

While SRV is increased in slickwater fracturing, production is high only initially and then drops rapidly to a lower sustained production since there is little access to hydrocarbons far field from the wellbore.

Like slickwater fracturing, conventional fracturing operations typically render an undesirably lengthy primary fracture.

While a greater number of secondary fractures may be created farther from the wellbore using viscous fluids versus slickwater, fluid inefficiency, principally exhibited by a reduced number of secondary fractures generated near the wellbore, is common in conventional hydraulic fracturing operations.

This decreases the efficiency of the stimulation operation.

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