Filter Cake Removal Using Thermochemical Reaction

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Solution Overview

Problem

The formation of an impermeable filter cake during drilling operations in oil wells causes reservoir damage and increases the breakdown pressure required for fracturing, especially in horizontal wells, due to the invasion of drilling fluid components and prolonged contact with the reservoir.

Innovation Solution

A method involving a mixture of a chelating agent and a thermochemical is used to remove the filter cake and create microfractures, reducing breakdown pressure by generating heat and pressure, which facilitates the simultaneous removal of filter cake and fracturing of the wellbore.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If drilling fluid is used to form a filter cake during drilling operations, then the borehole stability is maintained and filtrate leak-off is prevented, but the breakdown pressure for fracturing increases significantly

Engineering Contradiction:

Improveborehole stabilityVSAvoidbreakdown pressure

Core Design Contradiction:

ReliabilityVSStress or pressure

Solution Approach 1:

The patent applies preliminary action by removing the filter cake before the fracturing operation. The composition is injected into the wellbore to chemically react with and remove the filter cake that was formed during drilling, thereby eliminating the barrier that would otherwise increase breakdown pressure during subsequent fracturing operations

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent utilizes parameter changes by employing a composition that undergoes thermal decomposition to generate heat and gas. This changes the physical and chemical parameters of the wellbore environment, allowing the composition to effectively remove the filter cake through chemical reaction and mechanical disruption

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If drilling fluid components invade the reservoir formation, then the filter cake is formed to prevent further invasion, but a skin of reduced permeability is created around the wellbore

Engineering Contradiction:

Improvefiltrate leak-off preventionVSAvoidskin damage

Core Design Contradiction:

Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

The patent applies the taking out principle by selectively removing the harmful filter cake and skin components from the wellbore and formation interface. The composition chemically reacts with and extracts the drilling fluid residues, weighting materials, and polymers that constitute the skin, thereby restoring formation permeability without affecting the reservoir formation itself

Inventive Principle:

Principle #2Taking out (Extraction)

3Productivity

If conventional filter cake removal methods are used, then the filter cake is removed to allow reservoir fluid flow, but the process is time-consuming and requires multiple separate operations

Engineering Contradiction:

Improvewell cleanup efficiencyVSAvoidcleanup operation time

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The patent applies the merging principle by combining multiple functions into a single composition and operation. The composition simultaneously performs filter cake removal, skin damage remediation, and preparation for fracturing operations, eliminating the need for multiple separate cleanup steps and significantly reducing the time required for well completion

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent demonstrates universality by designing a single composition that can effectively remove various types of filter cakes and skin damages caused by different drilling fluid systems. The composition is universally applicable to both water-based and oil-based drilling fluids, making it a versatile solution for different well completion scenarios

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

The method achieves a significant reduction in breakdown pressure, with lab testing indicating a 85% decrease, allowing for efficient well cleanup and reduced pressure requirements for fracturing, compared to conventional methods.

Implementation Method 1

reacting the chelating agent and the thermochemical to produce heat and pressure

Methodology Applied

Scientific EffectExothermic reaction: Exothermic Reaction

Implementation Method 2

reacting the chelating agent and the thermochemical to produce heat and pressure

Methodology Applied

Scientific EffectPressure generation from chemical reaction: Chemical Bonding

Data Source

PatentUS11339319B2Reduction of breakdown pressure by filter cake removal using thermochemicals

Publication Date: 2022.05.24 SAUDI ARABIAN OIL CO

AI summary

A method for the simultaneous removal of filter cake from a wellbore and fracturing of the wellbore using a mixture including a chelating agent and a thermochemical. The method including feeding a mixture into the wellbore, contacting the filter cake with the mixture, reacting the chelating agent and the thermochemical to produce heat and pressure, removing the filter cake from the wellbore, and creating microfractures in the wellbore using pressure produced from the reacting.