Ishtiaque Anwar, John C. Stormont, and Mahmoud Reda Taha
Department of civil, construction and environmental engineering, University of New Mexico, Albuquerque, NM, United States
Wellbores provide below ground access for a multitude of operations, including fluid storage, waste disposal, and oil/gas exploration. These wellbores typically consist of a steel casing surrounded by cement which creates a seal between the host rock and the casing. The integrity of the cement can easily be compromised from factors such as construction-related flaws, the harsh chemical environment within a wellbore, and thermal and mechanical stress changes acting on the wellbore. Crude oil is a natural carbonaceous fluid, a complex mixture of a variety of chemical compounds (polar and non-polar), and it can leak upward through cement fractures in the wellbore casing. These leaks can cause substantial environmental contamination. Also, this can substantially compromise the functionality of the wellbore system. Modified Portland cement, polymer-based compounds, and swelling technologies have been used to repair leaky wells. However, these materials/techniques are not always cost-effective and applicable for small aperture fractures. The need for an economically feasible solution that exhibits universal effectiveness is critical to eliminate further wellbore flaws and environmental pollution.
Researchers from the University of New Mexico have utilized the technique of in-situ migration and separation of ions/components from crude oil to seal wellbore cement fractures. The pressure gradient that drives the crude oil leakage in the wellbores causes aggregation of tacky particles or micelle deposition in crude oil. A thin layer of micelle deposition adsorbed in fracture interface has been observed experimentally, which can temporarily reduce the fracture aperture but does not provide a permanent solution. Sufficient gas or liquid pressure, such as during a mechanical integrity test, will dislodge the deposited micelles and negate the sealing effect. The proposed technique will improve the clogging mechanism and cause comparatively thicker and more viscous deposition in the fracture interface by an added attraction energy between the fracture interface and micelles. Induced liquid flow opposite to the direction of the crude oil leakage will not only be an effective approach to reduce leakage rate but also accelerate the deposition mechanism. Further, this technique will generate an additional motion of tacky dispersed particles in the crude oil, which will aid in blocking the leakage route. With simpler control, such a technique is capable of effectively sealing a variety of cement fractures in multiple leaky wellbores simultaneously.
Advantages:
- Simultaneously applicable to multiple leaky wellbores (old and new)
- Effectively seals multiple small fractures of varying aperture size and roughness
- Affordable and cost-effective leakage repair solution
- Efficient elapsed time-fix without continuous human interaction
- Applicable to both detectable and undetectable fractures with active leakage
- Can be utilized in conjunction with conventional repair methods to reduce cost
- Substantially reduces the galvanic corrosion of the wellbore casing
- Realtime automatic/ remote adjustment is possible based on need
For more details: https://unm.flintbox.com/public/project/58079/