Wellbore Filter Cake Permeability via Chelation Treatment

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The challenges of managing lost returns and differential pressure sticking in wellbore drilling operations, particularly with non-aqueous drilling fluids, include low fluid loss and filter cake permeability issues, leading to costly and hazardous events such as fluid loss and wellbore instability.

Innovation Solution

A method involving the use of a treating fluid to remove metallic weighting agents from the filter cake, followed by a proppant slurry to increase filter cake permeability, which can include chelation agents like EDTA or potassium formate, to enhance fracture closure stress and prevent flowback and sticking events.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional LCM and barite are used to build fracture closure stress, then the immobile mass forms to increase closing stress, but very high fluid loss is needed which results in flowback and wellbore instability

Engineering Contradiction:

Improvefracture closure stressVSAvoiddrilling fluid loss

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The patent removes metallic weighting agents (barite) from the filter cake using chelation agents. This extraction prevents the need for high fluid loss to form immobile mass, as the chelation process directly creates permeability without requiring excessive fluid loss that would cause flowback.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces chelation agents as an intermediary substance that facilitates the removal of metallic weighting agents from the filter cake. This intermediary mechanism enables permeability enhancement without directly requiring high fluid loss, thus avoiding flowback while achieving fracture closure stress.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the filter cake permeability is low, then wellbore stability is maintained, but lost returns occur when drilling pressure exceeds formation strength

Engineering Contradiction:

Improvewellbore stabilityVSAvoidlost returns

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent changes the permeability parameter of the filter cake by removing metallic weighting agents through chelation. This parameter change allows the filter cake to transition from low permeability (which maintains stability but causes lost returns) to optimized permeability (which prevents lost returns while maintaining stability).

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies chelation treatment preliminarily to modify the filter cake properties before lost returns can occur. By pre-enhancing permeability through metallic agent removal, the system prevents the harmful effect of lost returns while maintaining wellbore stability during subsequent drilling operations.

Inventive Principle:

Principle #10Preliminary action

3Stress or pressure

If metallic weighting agents are retained in the filter cake, then wellbore pressure is maintained, but fluid loss is insufficient to form immobile mass for fracture treatment

Engineering Contradiction:

Improvewellbore pressureVSAvoidfluid loss

Core Design Contradiction:

Stress or pressureVSQuantity of substance

Solution Approach 1:

The patent replaces the mechanical system of using high fluid loss to form immobile mass with a chemical system using chelation agents to remove metallic weighting agents. This substitution achieves permeability enhancement and immobile mass formation without relying on high fluid loss, thus maintaining wellbore pressure while avoiding the fluid loss problem.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 significantly increases filter cake permeability, reducing the risk of lost returns and differential pressure sticking, allowing for safer and more efficient drilling operations by forming an immobile mass and maintaining wellbore integrity.

Implementation Method 1

contacting a filter cake with a treating fluid to remove metallic weighting agents from the filter cake

Methodology Applied

Scientific EffectChelation:

Implementation Method 2

contacting the filter cake with a proppant slurry, wherein the proppant slurry contacts the filter cake concurrently with the treating fluid or after the treating fluid contacts the filter cake

Methodology Applied

Scientific EffectPermeability enhancement through immobile mass formation:

Data Source

PatentUS7681644B2Managing lost returns in a wellbore

Publication Date: 2010.03.23 EXXONMOBIL UPSTREAM RESEARCH COMPANY(US)

AI summary

A method of managing lost returns in a wellbore includes contacting a filter cake with a treating fluid to remove metallic weighting agents from the filter cake, wherein the filter cake is disposed on a face of a formation fracture in the wellbore. The method also includes contacting the filter cake with a proppant slurry, wherein the proppant slurry contacts the filter cake concurrently with the treating fluid or after the treating fluid contacts the filter cake. This method may include increasing the filter cake permeability and may utilize a barite removal agent, such as a chelation agent. At least one related wellbore management method creates a fracture in the wellbore and props open the fracture to increase wellbore integrity to utilize higher weight drilling fluids and prevent fractures from forming further down the wellbore.