Development the self-healing concept for well cement support integrity maintenance. Theory and practice

Abstract

Oftentimes oil and gas wells can be affected to various technological as well as chemical and natural stresses. Perforations, fracturing, side tracking from under the casings shoe, formation integrity testings all these lead to the cement sheath fragility and the annulus integrity deterioration causing the emergence of net of cracks in the cement sheath, which contribute to nascence of behind-the-casing flows.
 World statistics say that the issues of casing string-borehole annulus unsealing prevention, as well as the effective restoration of the cement sheath integrity in the presence of a wide range of water-shutoff materials and technologies for inflows bounding, do still remain open and require non-standard solutions. In this connection, the development of “self-healing” plugging material, which allows the cement stone to independently regenerate its integrity, thereby excluding technological shutdowns and the intervention of repair equipment, is one of the highest priority tasks and promising methods for eliminating behind-the-casing flows, accompanied by restoring the integrity of the well cement sheath. An advanced alternative to the traditional plugging material is elaboration of "self-healing" cements, which is hopeful in the line of the above-mentioned peculiarities.