Methods of Enhancing the Fracture Conductivity of Multiple Interval Fractures in Subterranean Formations Propped with Cement Packs

Abstract

Methods of treating a wellbore in a subterranean formation having a top portion and a bottom portion, and a middle portion therebetween. The method includes providing a jetting fluid; providing a cement slurry; and providing a breakable gel fluid. Then introducing the jetting fluid into the bottom portion of the wellbore to create or enhance a bottom portion fracture; introducing the jetting fluid into the top portion of the wellbore to create or enhance a top portion fracture; introducing the cement slurry into the top portion fracture; introducing the cement slurry into the bottom portion fracture; and introducing the breakable gel fluid into the wellbore so as to prevent the expandable cementitious material from migrating out of the top portion fracture and bottom portion fracture. The expandable cementitious material is cured so as to form a cement pack, the breakable gel fluid is broken and removed from 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

The present invention provides a method for creating a cement pack in a subterranean formation by introducing a jetting fluid, a cement slurry, and a breakable gel fluid into the wellbore. The jetting fluid is introduced at a pressure sufficient to create fractures in the top, middle, and bottom portions of the wellbore. The cement slurry is then introduced into the fractures to form a cement pack. The breakable gel fluid is introduced to prevent the cementitious material from migrating out of the fractures. The cement is then cured to form a microfracture in the subterranean formation. The breakable gel fluid is broken and removed from the wellbore. The technical effect of this invention is to provide a reliable and effective method for creating a cement pack in a subterranean formation.

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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