Explore and Study on Well Cementing Anti-Water-Channeling Self-Healing Agent

An anti-water-channeling self-healing agent has been developed to deal with channeling in annular spaces after well cementing. This anti-water-channeling self-healing agent has a core-shell structure, it uses highly water absorbent resin as the core material and the size of the core (a sample passing 140 mesh screen) increases exponentially from original 100 μm to 1898 times of the original size in 30 s after absorbing water, and stabilizes at 2200 times of the original size in 120 s. Another 120-mesh sample absorbs water of 892 times of its original size in 30 s and stabilizes at 1950 times of the original size in 120 s. The core, after wrapped on its surface, does not absorb water for 3 h at 90℃. The anti-water-channeling self-healing agent can effectively plug fractures. When the cement is hydrated, the shell is broken and the anti-water-channeling self-healing agent then acquires water absorbency and self-healing ability. Core experiment showed that the anti-water-channeling self-healing agent can plug fractures in 40 min at 90℃and 2 MPa. Cement slurry test showed that normal density cement slurries containing 4% anti-water-channeling self-healing agent have good rheological property and controllable filtration rate, the thickening time of the cement slurries is linear and normal, and the set cement has high compressive strength, satisfying the needs of shallow well cementing.