Methods of Enhancing Fracture Conductivity of Subterranean Formations Propped with Cement Pillars

Abstract

Methods of treating a subterranean formation having at least one fracture including providing a cement slurry comprising an expandable cementitious material and a breakable foamed carrier fluid, wherein the expandable cementitious material is capable of consolidating to form a plurality of expandable cementitious material aggregates and wherein the breakable foamed carrier fluid is capable of coating and isolating the expandable cementitious material aggregates; introducing the cement slurry into the fracture; curing the expandable cementitious material aggregates so as to form a cement pillar within the fracture in the subterranean formation, wherein the curing of the expandable cementitious material aggregates expands the expandable cementitious material aggregates such that at least one microfracture is created within the fracture; breaking the breakable foamed carrier fluid; removing the broken breakable foamed carrier fluid from the subterranean formation; and acid-fracturing the at least one fracture in the subterranean formation.

Description

BACKGROUND[0001]The present invention provides methods of enhancing fracture conductivity within propped subterranean formations using a cementitious material and methods of delivering and / or treating such cementitious material.[0002]Subterranean wells (e.g., hydrocarbon producing wells, water producing wells, and injection wells) are often stimulated by hydraulic fracturing treatments. In hydraulic fracturing treatments, a viscous treatment fluid is pumped into a portion of a subterranean formation at a rate and pressure such that the subterranean formation breaks down and one or more fractures are formed. While the treatment fluid used to initiate the fracture is generally solids-free, typically, particulate solids, such as graded sand, are suspended in a later portion of the treatment fluid and then deposited into the fractures. These particulate solids, or “proppants,” serve to prop the fracture open (e.g., keep the fracture from fully closing) after the hydraulic pressure is re...

AI Technical Summary

Benefits of technology

This patent describes methods for improving the conductivity of fractures in propped subterranean formations using cementitious materials. These methods involve delivering and curing the cement slurry within the fracture to form a cement pillar. The cement slurry can include an expandable cementitious material that can consolidate and create microfractures within the fracture. The cement slurry can also be broken and removed, followed by an acid-fracturing process to further improve the conductivity of the fracture. Overall, the invention provides methods for enhancing the conductivity of fractures in subterranean formations via cement materials.

Problems solved by technology

Thus, the fracture porosity is closely related to the strength of the placed proppant and tight proppant packs are often unable to produce highly conductive channels within a fracture, while a reduced volume of proppant is unable to withstand fracture closure.

Moreover, hydraulic fracturing in soft rock formations, such as carbonate formations, is often inadequate to create conductive pathways because the proppant and carbonate formation together are unable to withstand closure pressure.

The substantial volume of aqueous fluid introduced into a formation during traditional fracturing treatments may also result in dilution of later-placed treatment fluids, impairment of produced fluid flow due to formation fluid retention, or damaged formation portions causing reduced hydrocarbon permeability due to fluid-induced swelling of the formation.

Additionally, traditional hydraulic fracturing treatments alone may create only shallow fractures near the wellbore head, substantially impairing the conductivity potential of a subterranean formation as a whole.

However, such degradable particulates are often unpredictable and may lead to unconnected and independent interstitial spaces within the proppant pack that fail to enhance conductivity, but rather form pockets that trap produced fluids.

Additionally, the placement of the degradable particulates may not be predictably uniform throughout the proppant pack, again leaving only pockets that trap produced fluids rather than contributing to an interconnected interstitial network for fluids to flow.

Fracture-acidizing is limited due to acid spending or leakoff, resulting in fracture extension termination.

Fracture-acidizing may also be unable to overcome the drawbacks of fracturing soft rock formations, failing to maintain conductive channels after fracture closure.

While this technique is effective at stimulating deep fractures within a subterranean formation, handling of explosives or propellants poses great threat to operators during well stimulation.

Additionally, the explosives or propellants may detonate at unplanned or unpredictable intervals within the formation, interfering with the conductivity potential of the well.

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