Two-Stage Fracturing Method for Enhancing Conductivity
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Solution Overview
Problem
Conventional hydraulic fracturing methods face challenges in achieving effective propped fracture length and fracture conductivity, particularly when using fluids without viscosifying polymers or surfactants, which result in poor proppant transport and conductivity issues due to filter cake deposition.
Innovation Solution
A method involving two-stage fracturing, where one stage is proppant-free and the other contains a breaker with affinity for viscosifying polymers or viscoelastic surfactants, allowing for partial degradation of filter cakes and enhanced fracture conductivity, especially applicable with fluids like water, salt brine, or slickwater.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fracturing fluids with viscosifying polymers are used to achieve high viscosity and control leakoff, then fluid efficiency and leakoff control are improved, but filter cake deposition occurs causing conductivity damage
Solution Approach 1:
The fracturing treatment is divided into multiple stages: an initial stage using polymer-free fluid to create fracture width, followed by a proppant laden stage, and finally a breaker stage to degrade filter cake. This segmentation allows each stage to perform its specific function without the harmful effects of filter cake deposition affecting overall conductivity.
Solution Approach 2:
The breaker is introduced in a separate stage after proppant placement is complete. This preliminary action of introducing the breaker after proppant placement ensures that proppant transport is not compromised by premature viscosity reduction, while still allowing filter cake degradation to enhance final conductivity.
2Productivity
If oxidative breakers are used at elevated temperatures to reduce viscosity and improve recovery, then fluid recovery is enhanced, but proppant transport is compromised due to rapid reaction
Solution Approach 1:
The treatment is segmented into distinct temporal stages: first proppant laden fluid is pumped to establish proppant column, then breaker is introduced in a separate stage. This segmentation ensures proppant transport occurs before breaker activation, preventing the harmful effect of premature viscosity reduction while maintaining fluid recovery benefits.
Solution Approach 2:
Proppant placement is completed before the breaker is introduced. This preliminary completion of proppant transport ensures that the harmful effect of rapid oxidative reaction does not interfere with proppant column formation, while still allowing effective fluid recovery through subsequent viscosity reduction.
3Productivity
If proppant laden fluid is pumped to create proppant column, then fracture conductivity is improved, but viscosity must be reduced for effective proppant transport
Solution Approach 1:
The treatment is divided into sequential stages where proppant laden fluid is pumped first to establish the proppant column, then breaker is introduced in a separate stage to reduce viscosity. This segmentation allows the fluid to maintain high viscosity during proppant transport for effective placement, then viscosity is reduced afterward to improve recovery without compromising proppant column integrity.
Solution Approach 2:
Proppant column formation is completed as a preliminary action before viscosity reduction occurs. This ensures that proppant placement is achieved while fluid maintains necessary viscosity, and viscosity reduction is deferred to a later stage when proppant transport is no longer the primary concern, thus avoiding the trade-off between conductivity and viscosity stability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach increases effective propped fracture length and fracture conductivity by degrading filter cakes, improving proppant placement and transport, and creating a partial monolayer fracture, thus enhancing well productivity.
Implementation Method 1
at least one of the stages contains a breaker which has affinity for a viscosifying polymer or viscoelastic surfactant present in the other stage
Implementation Method 2
The requisite viscosity is typically obtained by the gellation of viscosifying polymers and/or surfactants in the fracturing fluid
Implementation Method 3
the proppant remains in the fracture in the form of a permeable 'pack' that serves to 'prop' the fracture open
Implementation Method 4
a fracturing fluid is pumped at high pressures and high rates into a wellbore penetrating a subterranean formation to initiate and propagate a fracture in the formation
Data Source
AI summary
The method disclosed herein includes the introduction of proppant-free stage and a proppant laden stage into the wellbore and/or subterranean formation. The method increases the effective fracture width and enhances fracture conductivity within the formation. Either the proppant-free stage or the proppant laden stage contains a breaker. The other stage contains a viscosifying polymer or viscoelastic surfactant to which the breaker has affinity. The proppant-free stage may be introduced prior to introduction of the proppant laden stage into the wellbore and/or formation. Alternatively, the proppant laden stage may be introduced into the wellbore and/or formation prior to introduction of the proppant-free stage.