Fluid Diversion in Horizontal Wellbore Re-fracturing

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Solution Overview

Problem

Existing methods for re-fracturing horizontal wellbores often fail to effectively create new fractures due to fluid entering prior fractures, and techniques like expandable tubulars or cladding are costly and inefficient.

Innovation Solution

A method and system involving a tubing string with different fluids in the annulus and interior, where the first fluid with higher viscosity is used to divert and initiate re-fracturing, followed by a second fluid with lower viscosity to enhance fracture formation, and a third fluid to further re-fracture, while monitoring with microseismic devices to optimize results.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If fracturing fluid is pumped into the wellbore to create new fractures, then new fracture pathways are formed to increase hydrocarbon production, but the fracturing fluid enters prior fractures instead of creating new fractures

Engineering Contradiction:

Improvehydrocarbon productionVSAvoidfracture creation effectiveness

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The wellbore is divided into multiple isolated zones using packers positioned at different locations. Each zone can be independently fractured by pumping fracturing fluid through tubing string segments corresponding to that zone, preventing fluid from entering prior fractures in other zones and ensuring effective new fracture creation in the targeted zone.

Inventive Principle:

Principle #1Segmentation

2Reliability

If expandable tubulars or cladding procedures are used to block flow paths to old fractures, then new fracture formation is promoted, but the cost and complexity increase significantly

Engineering Contradiction:

Improvefracture diversion effectivenessVSAvoidwellbore intervention complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Instead of modifying the tubulars or casing with expandable structures or cladding, the invention extracts the flow path control function to a separate element - the packer. The packer is inserted into the annulus between the tubing string and casing to physically block fluid flow to prior fractures, simplifying the overall system while achieving the same fracture diversion effect.

Inventive Principle:

Principle #2Taking out (Extraction)

3Productivity

If fracturing fluid is pumped at high pressure to fracture the formation, then fracture pathways are created, but existing fractures are re-fractured instead of creating new production zones

Engineering Contradiction:

Improvenew fracture pathwaysVSAvoidfracture location control

Core Design Contradiction:

ProductivityVSAdaptability or versatility

Solution Approach 1:

The packer is positioned at a specific location in the annulus to create a localized seal that isolates a particular zone. This allows high-pressure fracturing fluid to be directed precisely to a desired location in the formation, creating new fractures in under-stimulated areas while preventing fluid from diverting into existing fractures elsewhere in the wellbore.

Inventive Principle:

Principle #3Local quality

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 allows for targeted and efficient re-fracturing of horizontal wellbores, increasing hydrocarbon production by creating new fractures without entering existing ones, thus overcoming the limitations of previous methods.

Implementation Method 1

providing a first fluid in an annulus between the tubing string and the horizontal wellbore, wherein a portion of the horizontal wellbore beyond an end of the tubing string includes the first fluid. providing a second fluid within the tubing string, wherein the second fluid differs from the first fluid

Methodology Applied

Scientific EffectViscosity:

Implementation Method 2

sealing the annulus adjacent to the surface location and pumping the second fluid down the tubing string to initiate a re-fracture of the first location while the annulus is sealed adjacent to the surface location

Methodology Applied

Scientific EffectSealing:

Implementation Method 3

monitoring the first location with a microseismic device and determining an effectiveness of the re-fracturing based on data from the microseismic device

Methodology Applied

Scientific EffectMicroseismic:

Data Source

PatentUS9470078B2Fluid diversion through selective fracture extension

Publication Date: 2016.10.18 BAKER HUGHES CO

AI summary

A system and method that uses fluid diversion to selectively re-fracture a location of a multizone horizontal wellbore. A tubing string is extended from the surface to a location within the wellbore that is to be re-fractured. The annulus between the tubing string and the wellbore contains a first fluid and a second fluid is contained within the tubing string. The annulus may be sealed off at or near the surface and the second fluid is pumped out of the tubing string to initiate the re-fracture of the first location. The annulus seal may then be unset and the first fluid may be pumped down the annulus simultaneous to pumping a third fluid down the tubing string to re-fracture the first location. After re-fracturing the first location, the first location may be hydraulically isolated from the wellbore to permit a second location to be re-fractured.