Chemical Casing Removal via Acidic Oxidation
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Solution Overview
Problem
The process of removing iron-containing casing from well bores during plugging and abandonment is costly and time-consuming, requiring heavy equipment like rigs, which are then unavailable for new well preparation.
Innovation Solution
A method involving the injection of an acidic solution into the well bore to accelerate the oxidation of iron in the casing, allowing the iron cations to dissolve in the solution, which is then removed, along with a system comprising fluid lines for injection and removal of the solution and a separation system for iron ions and hydrogen.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional rig-based methods are used to remove iron-containing casing, then complete removal can be achieved, but the process is costly and time-consuming
Solution Approach 1:
The patent replaces mechanical rig-based removal systems with a chemical dissolution process. Acidic solution is injected into the well bore to chemically dissolve the iron-containing casing, transforming a mechanical operation into a chemical one. This substitution eliminates the need for heavy equipment and reduces operational time while maintaining complete removal effectiveness.
Solution Approach 2:
The patent changes the fundamental approach from mechanical force application to chemical parameter utilization. By introducing acidic solutions with specific pH levels and compositions, the process leverages chemical reactions to dissolve iron-containing materials. This parameter change from mechanical to chemical domain enables faster, more efficient casing removal without requiring rig deployment.
2Reliability
If rig-based equipment is deployed for casing removal, then effective removal can be performed, but the rig becomes unavailable for new well preparation
Solution Approach 1:
The patent eliminates the need for rig-based mechanical systems by using chemical dissolution methods. The acidic solution can be injected through existing well infrastructure or simple injection equipment, leaving the rig available for its primary function of preparing new wells. This substitution restores equipment versatility and eliminates the conflict between abandonment and exploration operations.
3Adaptability or versatility
If chemical dissolution method is used, then rig availability is maintained and costs are reduced, but hydrogen gas is liberated during the process
Solution Approach 1:
The patent addresses the hydrogen gas byproduct through controlled management strategies. The acidic solution is circulated through the well bore, and hydrogen gas is allowed to escape naturally or is captured for safe disposal. This approach converts the potentially harmful hydrogen evolution into a manageable process parameter, eliminating the need for complex gas handling equipment while maintaining safety.
4Productivity
If acidic solution is injected to dissolve iron casing, then removal efficiency increases, but iron cations and hydrogen must be separated from the solution
Solution Approach 1:
The patent extracts and removes the dissolved iron cations and hydrogen gas from the acidic solution through simple separation processes. The circulated solution is filtered or allowed to settle, removing iron compounds and gas bubbles. This extraction step is implemented using basic separation technology rather than complex systems, maintaining operational simplicity while enabling continuous acid recycling and well bore cleaning.
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 allows for selective and efficient removal of iron-containing casing, reducing the need for rig-based equipment and minimizing costs by enabling targeted casing removal, thus facilitating the permanent plugging of wells without the need for extensive rig deployment.
Implementation Method 1
injecting an acidic solution into said well bore, wherein said solution contacts said iron-containing casing and thereby accelerates oxidation of iron to iron cations
Implementation Method 2
allowing said iron cations to dissolve in said acidic solution
Data Source
AI summary
There is provided a method of chemically removing iron-containing casing from a well bore comprising injecting an acidic solution into said well bore, wherein said solution contacts said iron-containing casing and thereby accelerates oxidation of iron to iron cations, allowing said iron cations to dissolve in said solution, and removing said solution from said well bore. There is further provided a batch method of removing iron-containing casing from a well bore comprising injecting an acidic solution into said well bore, wherein said acidic solution contacts said iron-containing casing and thereby accelerates oxidation of iron to iron cations, and allowing said iron cations to dissolve in said acidic solution, wherein said well bore is at least partially open to the atmosphere.