Multi-Stage Fracturing with Acid Dissolution for Complex Networks
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Solution Overview
Problem
Conventional fracturing methods often fail to create complex fracture networks in subterranean formations due to stress conditions that discourage the extension of fractures in multiple directions, limiting hydrocarbon production.
Innovation Solution
The method involves a multi-stage fracturing process using a first fluid to create hydraulic fractures, followed by a second fluid with an acid component to dissolve the formation and create induced fractures, and a reactive fluid to relieve stress and connect natural and hydraulic fractures, forming a complex fracture network.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional fracturing methods are used, then hydraulic fractures can be created, but complex fracture networks cannot form due to stress conditions that discourage multi-directional extension
Solution Approach 1:
The treatment is divided into multiple sequential stages: first creating hydraulic fractures with fracturing fluid, then inducing secondary fractures with acid fluid, and finally connecting them through stress shadow effects. This segmentation allows each stage to build upon the previous one, creating complex networks that single-stage methods cannot achieve
Solution Approach 2:
Hydraulic fractures are created first as preliminary structures before introducing the acid fluid. These pre-formed fractures serve as conduits and stress concentrators that guide subsequent acid-induced fracture development, ensuring that the complex network forms in predictable, productive patterns
2Productivity
If stress conditions are present in the formation, then hydraulic fractures can be created, but natural fracture dilation is prevented, limiting fracture network creation
Solution Approach 1:
The method changes the chemical parameter of the treatment fluid by introducing acid components that react with and dissolve formation minerals. This chemical parameter change allows natural fractures to dilate and connect even under stress conditions that would otherwise prevent such dilation, as the acid weakens the rock structure surrounding the fractures
3Productivity
If a multi-stage process with multiple fluids is used, then complex fracture networks can be created, but the process complexity increases
Solution Approach 1:
The acid fluid performs multiple functions: it dissolves formation minerals to create induced fractures, reacts with stress shadows to promote fracture connection, and enhances permeability through chemical etching. This multi-functionality consolidates what would otherwise require separate treatment stages into a single versatile fluid intervention
Solution Approach 2:
The fracturing process maintains continuous useful action by seamlessly transitioning from hydraulic fracture creation to acid-induced fracture development. The stress shadows and pressure differentials created in the first stage continuously drive the second stage, eliminating idle periods and ensuring uninterrupted fracture network development
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 enhances fluid flow and permeability, increasing hydrocarbon production by creating a complex fracture network that connects natural and hydraulic fractures, thereby improving well productivity, especially in low-permeability formations like shale reservoirs.
Implementation Method 1
allowing the acid component to dissolve at least a portion of the subterranean formation to form one or more induced fractures
Data Source
AI summary
A method comprising: introducing a first fluid into a wellbore above a fracture gradient of a subterranean formation penetrated by the wellbore to create a first plurality of fractures within a first portion of the subterranean formation; introducing a second fluid comprising at least one acid component into the wellbore above the fracture gradient of the subterranean formation penetrated by the wellbore to create a second plurality of fractures within a second portion of the subterranean formation; allowing the second fluid to enter at least one natural fracture in the first or second portion of the subterranean formation allowing the acid component to dissolve at least a portion of the subterranean formation to form one or more induced fractures in fluidic communication with the natural fracture, at least some of the first plurality of fractures, and at least some of the second plurality of fractures.