Supercritical CO2 Wellbore Scale Removal
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Solution Overview
Problem
Existing wellbore cleaning methods are inefficient in removing non-soluble scale, often requiring costly and time-consuming processes like milling, chemicals, and gelling agents, especially in depleted reservoirs where formation damage is a concern.
Innovation Solution
Supercritical carbon dioxide is directed through a nozzle to impact the wellbore wall, changing phases to solid, liquid, and gas, acting as an abrasive to remove scale, and is used in underbalanced conditions to prevent formation damage, with the removed scale being lifted through the annulus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional methods (milling, chemicals, gelling agents) are used to remove non-soluble scale, then scale removal is achieved, but cost and time increase significantly
Solution Approach 1:
The patent replaces conventional mechanical milling systems with a jetting system that uses supercritical carbon dioxide. The supercritical CO2 is injected through nozzles at high velocity to impact and remove scale deposits from the wellbore wall, eliminating the need for mechanical mill motors and complex drilling equipment while significantly reducing operation time and cost.
Solution Approach 2:
The patent utilizes phase changes of carbon dioxide (from supercritical to gas phase) to achieve scale removal. By controlling pressure and temperature parameters, the CO2 transitions to a supercritical state for injection, then expands to gas phase upon contact with the wellbore wall, creating a powerful jetting effect that removes scale without requiring prolonged mechanical operation.
2Reliability
If conventional cleaning methods are used, then scale is removed, but formation damage occurs in depleted reservoirs
Solution Approach 1:
The patent replaces aggressive mechanical milling that can damage formation structures with a controlled jetting process using supercritical CO2. The jetting action removes scale through focused impact forces that are confined to the scale deposits rather than propagating into the formation, thereby preventing formation damage while maintaining effective scale removal.
Solution Approach 2:
The patent uses carbon dioxide as an inert fluid that does not react with or damage the formation. The supercritical CO2 provides a clean, non-reactive environment for scale removal that avoids the chemical and mechanical damage associated with conventional methods, protecting the depleted reservoir formation from further harm.
3Productivity
If supercritical carbon dioxide is used to remove scale, then cost and time are reduced, but complex phase change control is required
Solution Approach 1:
The patent utilizes the inherent phase change properties of carbon dioxide at specific pressure and temperature conditions. By controlling injection parameters (pressure and temperature) to maintain supercritical state during transport, and allowing natural expansion to gas phase at the wellbore wall, the system achieves complex cleaning action through relatively simple parameter control rather than complex mechanical systems.
Solution Approach 2:
The supercritical CO2 system is self-regulating through its phase change behavior. When injected at supercritical conditions and allowed to expand upon contact with the wellbore environment, the CO2 automatically transitions to gas phase, creating the jetting effect and expansion forces needed for scale removal without requiring additional control mechanisms or complex device systems.
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 effectively removes non-soluble scale with significant cost and time savings, reducing formation damage by using the phase change and underbalanced conditions to efficiently lift the scale particles.
Implementation Method 1
A phase of the supercritical carbon dioxide is changed to solid, liquid, or gas phase of carbon dioxide
Implementation Method 2
Supercritical carbon dioxide impacts a wall of the wellbore at the specified depth
Implementation Method 3
acting as an abrasive to remove scale
Implementation Method 4
Supercritical carbon dioxide travels through a workstring positioned in a wellbore to a specified depth within the wellbore
Implementation Method 5
The removed scale is lifted to a topside facility
Data Source
AI summary
Supercritical carbon dioxide is directed into a wellbore to a specified depth. The supercritical carbon dioxide is directed at an inner surface of the wellbore at the specified depth. Scale is removed from the wall of the wellbore with the supercritical carbon dioxide.