Downhole Reactant Delivery for Controlled Fracture Initiation
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Solution Overview
Problem
Hydraulic fracture initiation in multi-stage horizontal wells is complex and poorly understood, leading to negative impacts such as near-wellbore tortuosity, uneven proppant distribution, and unpredictable fracture growth, which are exacerbated by the use of low-viscosity fluids and low injection rates, and current technologies lack effective methods for controlled fracture initiation compatible with modern fracturing workflows.
Innovation Solution
A method involving a tool string with a mechanical reactant delivery assembly and a perforating tool that releases chemical reactants to form a high-viscosity breakdown fluid, followed by explosive charges to initiate fractures, and subsequent pumping of follow-up fluids to optimize fracture propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional hydraulic fracturing with low-viscosity fluids and low injection rates is used, then the treatment process is simpler, but fracture initiation becomes uncontrolled and tortuosity increases
Solution Approach 1:
The patent applies preliminary action by pre-mixing chemical reactants in a downhole assembly before fracture initiation. The reactants are held in separate chambers and then mixed in-situ to create high-viscosity breakdown fluid exactly when and where needed, before the fracturing process begins. This pre-preparation of the fluid system resolves the contradiction by enabling controlled fracture initiation without requiring complex surface mixing equipment.
Solution Approach 2:
The patent uses chemical reactants as intermediaries to transform low-viscosity injection fluid into high-viscosity breakdown fluid downhole. The mechanical reactant delivery assembly introduces these chemical intermediaries that react to increase fluid viscosity locally, providing controlled fracture initiation while keeping the overall treatment process relatively simple.
2Productivity
If multi-stage hydraulic fracturing with simultaneous perforation cluster treatment is used, then productivity increases, but proppant distribution becomes uneven and tortuosity worsens
Solution Approach 1:
The patent applies local quality by creating high-viscosity breakdown fluid at specific downhole locations where perforation clusters are being treated. The mechanical reactant delivery assembly targets individual clusters or stages, allowing customized fluid viscosity characteristics at each treatment zone. This local application of high-viscosity fluid ensures uniform proppant distribution in each cluster while maintaining overall treatment efficiency across multiple stages.
3Manufacturing precision
If high-viscosity breakdown fluid is used to control fracture initiation, then fracture placement precision improves, but the complexity of fluid preparation and delivery increases
Solution Approach 1:
The patent replaces complex surface-based fluid preparation mechanical systems with a simpler downhole chemical reaction system. Instead of using large surface mixing equipment to prepare high-viscosity fluid, the invention uses compact mechanical reactant delivery assemblies that mix chemical reactants in-situ downhole. This substitution achieves the same fracture placement precision with significantly reduced surface equipment complexity.
Solution Approach 2:
The patent changes the viscosity parameter of the breakdown fluid by using chemical reactants that increase viscosity downhole. The mechanical reactant delivery assembly introduces reactants that chemically transform the low-viscosity injection fluid into high-viscosity breakdown fluid, achieving precise fracture placement through parameter change rather than through complex physical fluid preparation systems.
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
Enables controlled and uniform fracture initiation and propagation, improving proppant distribution and reducing tortuosity, thereby enhancing the effectiveness and efficiency of hydraulic fracturing treatments.
Implementation Method 1
releasing a plurality of chemical reactants from the mechanical reactant delivery assembly while the tool string is deployed within the wellbore to enable the plurality of chemical reactants to mix to form a breakdown fluid
Implementation Method 2
firing one or more explosive charges of the perforating tool to inject the breakdown fluid into the subterranean formation to initiate one or more fractures
Data Source
AI summary
Systems and methods presented herein are configured to facilitate effective fracture initiation. For example, a method includes deploying a tool string into a wellbore extending through a subterranean formation, wherein the tool string comprises a perforating tool and a mechanical reactant delivery assembly; releasing a plurality of chemical reactants from the mechanical reactant delivery assembly while the tool string is deployed within the wellbore to enable the plurality of chemical reactants to mix to form a breakdown fluid; and firing one or more explosive charges of the perforating tool to inject the breakdown fluid into the subterranean formation to initiate one or more fractures in the subterranean formation.