In terms of oilfield cementing, micro annuli in cement is a common issue. Micro annuli usually lead to production reduction and expensive remedial cost. The problem is caused by many factors and this article will focus on the most common reasons and how to deal with them.
There are many leaking wells in the world which can be challenging in many aspects. A lot of wells are shut off even if they can still be used for many years. Thus, rather than losing money, well owners could get a return of their investment when they can stop the leakage instead of shutting the well down completely.
These are micro-separation between pipe and cement as a result of a temperature or pressure change during the cementing setting process or after setting the cement. Also, micro-annulas can take place between cement and formation. This is less common; however, it can lead to a lack of bonding to the casing or formation and a potential communication channel.
Causes of Micro Annuli
During the setting of the cement, it is important to keep an eye on the cement behavior. The constant exposure of the slurry to forces and obstructions while being in the wet state paves the way for the occurrence of micro-annuli.
Below are the common causes:
Despite the commonality of micro-annuli in the cementing process, its occurrence can be reduced with proper planning that includes process and material selections. Also, it is necessary to have proper contingencies in place to deal with problem areas right away when micro-annuli take place.