Wellbores provide access beneath the ground for a multitude of operations, including fluid storage, waste disposal, and oil/gas exploration. They typically consist of a steel casing surrounded by cement to create a seal between the host rock and casing. The integrity of the cement can easily be compromised due to a number of factors, such as human error, the harsh chemical environment exhibited by the stored fluids, and the nature of surrounding geo-mechanical stresses. Leakage upward through the wellbore annulus can contaminate water-bearing formations, create hazardous surface conditions, and compromise the functionality of the wellbore. Multiple repair methods pertaining to wellbore defects exist, including Portland cement, polymer-based compounds and swelling technologies; however, numerous limitations have presented themselves. Despite their effectiveness, small aperture fractures and micro-cracks in manageable and harsh environments are often not repairable with existing techniques. Furthermore, these conventional repairs are not always cost-effective, thus wellbore storage construction & management companies require a more effective and low-cost approach for wellbore leakage repair.
Researchers at the University of New Mexico have developed a special colloidal mix or solution for wellbore repair. The proposed solution, eSolvs, can penetrate low permeability cracks and microannuli in order to repair any leaking defects. In order to repair the flaws, the solution replaces cavern fluid in the leakage zone. Once introduced to the space, excess solution can be recovered and reused, providing a more economically beneficial and environmentally conscious alternative. The eSolvs solution regulates the potential difference between the leakage in the wellbore and the wellhead, while maintaining a small electrical potential difference aided with a programmed micro-controller. Once applied, the solution repairs the defect over time, offering a permanent block. It can be used to effectively seal multiple fractures of different aperture sizes and roughness by appropriately adjusting the potential difference. The application technique is simple and straightforward for wellbores with steel casing. The underground storage system does not need to be depressurized because eSolvs can repair fracture under high pore pressure, making it a more practical solution. The technique is expected to work for both detectable and undetectable fractures.
- Penetrates into low permeability cracks
- Offers permanent blocking of leakage in cracks
- Applicable to both detectable and undetectable fractures
- Seals multiple fractures of different aperture sizes and roughness
- Used collectively with conventional repair methods to avoid the requirement of high-injection pressure
- Able to fix cracks at considerable leakage pressure
- Wellbore Repair
- Fluid Storage
- Waste Disposal
- Oil & Gas Exploration
Name: Andrew Roerick