Horizontal Well Refracturing via Stress Redistribution

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Refracturing in horizontal wells is challenging due to changes in stress patterns and depletion of rock intake over time, which reduces the efficiency of fluid injection and production, necessitating methods to alter stress levels and create new fractures for enhanced fluid stimulation without additional wellbore equipment.

Innovation Solution

A method involving geomechanical modeling to identify zones of varying stress levels, isolating existing fractures, creating small-sized auxiliary fractures to increase stress levels, and initiating refracturing in zones with originally high or medium stress levels, using a slurry of plugging particles and fibers to isolate fractures and propping agents to maintain increased stress, allowing for effective refracturing and reactivation of injection wells.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If refracturing is performed in depleted zones with low stress levels, then fluid injection efficiency is improved, but the fracture quickly enters mechanical barriers (high stress regions) and cannot extend further

Engineering Contradiction:

Improvefluid injection efficiencyVSAvoidfracture extension length

Core Design Contradiction:

ProductivityVSLength of moving object

Solution Approach 1:

The patent changes the stress field parameters by creating auxiliary fractures in high-stress regions, which redistributes the stress pattern and creates new low-stress zones that allow fracture propagation to extend further without immediately encountering mechanical barriers

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent segments the fracture system by creating multiple auxiliary fractures at different locations along the wellbore, dividing the single long fracture into multiple smaller segments that can be independently controlled and positioned in optimal stress zones

Inventive Principle:

Principle #1Segmentation

2Length of moving object

If refracturing is performed in non-depleted zones with high stress levels, then fracture extension length is improved, but fluid injection efficiency decreases due to mechanical barriers

Engineering Contradiction:

Improvefracture extension lengthVSAvoidfluid injection efficiency

Core Design Contradiction:

Length of moving objectVSProductivity

Solution Approach 1:

The patent modifies the stress distribution parameters by introducing auxiliary fractures that alter the local stress state, transforming high-stress regions into zones with reduced stress concentration, thereby improving fluid injection efficiency while maintaining fracture extension

Inventive Principle:

Principle #35Parameter changes

3Productivity

If multiple auxiliary fractures are created to alter stress distribution, then refracturing effectiveness is improved, but the complexity of the fracturing operation increases

Engineering Contradiction:

Improverefracturing effectivenessVSAvoidfracturing operation complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent employs a universal fracturing system that can perform multiple functions: creating main fractures, creating auxiliary fractures, and isolating zones, all through the same basic equipment and procedure, thereby reducing operational complexity despite the multi-stage nature of the treatment

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 effectively increases the stress level in depleted zones, enabling refracturing in previously non-preferable areas, enhancing oil recovery and maintaining efficient fluid injection over longer distances and larger volumes, thereby improving the overall production and stimulation of the formation.

Implementation Method 1

isolating existing fractures, creating small-sized auxiliary fractures to increase stress levels, and initiating refracturing in zones with originally high or medium stress levels, using a slurry of plugging particles and fibers to isolate fractures

Methodology Applied

Scientific EffectPlugging:

Implementation Method 2

using a slurry of plugging particles and fibers to isolate fractures and propping agents to maintain increased stress

Methodology Applied

Scientific EffectPropping:

Implementation Method 3

Hydraulic fracturing of the formation (frac), also referred to as hydraulic fracturing, is the main means to increase well production due to generation or expanding cracks or channels leading from the wellbore to the pay formation

Methodology Applied

Scientific EffectHydraulic fracturing: Fracture Mechanics

Data Source

PatentUS11091994B2Method of refracturing in a horizontal well

Publication Date: 2021.08.17 SCHLUMBERGER TECH CORP

AI summary

A horizontal well may be refractured or reactivated by generating a geomechanical model to estimate the stress level in the formation; identifying zones with high, medium, and low stress levels in the formation; isolating existing fractures in the horizontal well; injecting a fracturing fluid into the well to create at least one new fracture in a zone with a low stress level and packing the created fracture with proppant to increase the stress level in the zone; isolating the at least one newly created fracture; initiating refracturing in the zone with the high and/or medium stress level; identifying a location of the refracturing crack in the zone with the high and/or medium stress level; and developing the refracturing crack and packing it with proppant.