Chemical Casing Removal for Well Sealing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for removing well casing and tubing from oil/gas wells during plugging and abandonment or work-over operations are time-consuming, expensive, and generate debris, which complicates subsequent sealing or repair operations, and existing heat-based methods produce unpredictable seals due to mixed material compositions.
Innovation Solution
A method involving chemical reactions or rapid temperature changes to weaken and remove well casing/tubing, either by oxidation or embrittlement/softening, followed by mechanical stress or melting, to clear a path for plug deployment or repair, reducing debris and facilitating effective sealing or repair.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical means (milling or drilling) are used to remove well casing, then the casing can be removed from the bore hole, but the process is time consuming and expensive, and produces debris that interferes with subsequent operations
Solution Approach 1:
The patent replaces mechanical milling or drilling systems with a chemical reaction system. A reactive composition is introduced into the bore hole that chemically reacts with the casing material, dissolving or decomposing it without mechanical contact. This substitution eliminates the time-consuming mechanical removal process while avoiding debris generation, as the casing is converted into soluble or gaseous products.
Solution Approach 2:
The patent changes the physical-chemical parameters of the casing material through chemical reaction. By introducing a reactive composition with specific chemical properties (acidity, oxidizing capability), the casing material undergoes parameter changes including molecular structure breakdown, solubility increase, or phase transformation, enabling removal without mechanical force and without producing interfering debris.
2Reliability
If mechanical means (milling or drilling) are used to remove well casing, then the casing can be removed from the bore hole, but the process is expensive and produces contaminated debris requiring expensive disposal
Solution Approach 1:
The patent replaces mechanical milling or drilling systems with a chemical reaction system. A reactive composition is introduced into the bore hole that chemically reacts with the casing material, dissolving or decomposing it without mechanical contact. This substitution eliminates the time-consuming mechanical removal process while avoiding debris generation, as the casing is converted into soluble or gaseous products.
Solution Approach 2:
The patent transforms the casing material from a solid waste product into a recoverable or harmless substance through chemical reaction. The reactive composition converts the casing into soluble salts, gases, or other forms that can be easily removed from the bore hole with fluid circulation, eliminating the need for expensive contaminated debris disposal operations.
3Reliability
If heat generating mixtures (thermite) are used to melt well casing, then the casing can be removed, but the effectiveness of plugs formed from melted mixed materials is difficult to predict
Solution Approach 1:
The patent extracts the casing material from the bore hole through chemical dissolution rather than melting. The reactive composition selectively reacts with and removes the casing material, leaving the surrounding formation materials undisturbed. This prevents the mixing of different materials that occurs with melting methods, ensuring that any subsequently formed plug consists of homogeneous, predictable materials with reliable sealing properties.
Solution Approach 2:
The patent replaces mechanical milling or drilling systems with a chemical reaction system. A reactive composition is introduced into the bore hole that chemically reacts with the casing material, dissolving or decomposing it without mechanical contact. This substitution eliminates the time-consuming mechanical removal process while avoiding debris generation, as the casing is converted into soluble or gaseous products.
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 method efficiently clears well casing/tubing, minimizing debris and enabling the formation of effective seals across the well borehole cross-section, thereby simplifying plugging and abandonment or facilitating repair operations.
Implementation Method 1
delivering a chemical heating mixture to the target region and initiating the chemical heating mixture to melt the well casing/tubing
Implementation Method 2
subjecting the target region to a rapid temperature change so as to alter the physical properties of the well casing/tubing in the target region and thereby embrittle, soften or otherwise weaken the well casing/tubing
Implementation Method 3
initiating a chemical reaction between the chemical agent and the well casing or tubing, wherein the chemical reaction consumes one or more chemical components of the material from which the well casing or tubing is made
Data Source
Figure 1a~1e
AI summary
A method of clearing well casing or tubing from a target region of an oil/gas well borehole is provided. The clearance of the oil/gas well bore hole being achieved by employing chemical agents that consume, weaken or melt the well casing/tubing. In some aspects of the method the well casing is cleared to expose the rock formation within which the well borehole is formed so that the rock formation can be accessed from within the well casing/tubing. In other aspects of the method the removal of inner tubing structures is used to facilitate the unimpaired deployment of repair tools down the well borehole.