Study On Controlled-Release Microcapsule In Gas Channeling Prevention Cement Slurry System

The conventional cement can't meet the engineering technical requirements because of some adverse factors exit in the deep water surface cementing operations, such as low temperature, low fracture pressure of formations, shallow flow, etc. A new type of low temperature cement accelerator is presented for this purpose. The microcapsule is coated in cement accelerator. The accelerator does not work when cement slurry is premixed and pumped, so the cement slurry can maintain a good liquidity. But when the cement slurry reaches the predetermined location, the microcapsules in the accelerator will split, then the cement rapidly solidifies. As a result, the gas channeling can be effectively prevented.On the basis of analysis of the preparation methods of microcapsule, the phase separation method and solvent evaporation method are chose in this paper. In addition, the optimal experimental parameters are obtained through the orthogonal tests. The preparation principle and the effect factors of the microcapsule are inferred by the slow-release performance testing and microstructure observation. The contrast experiment result shows that the accelerator microcapsule produced by solvent evaporation method is well-distributed and has a much smaller diameter, a better slow-release effect can be gotten. In order to meet the slow-release requirements, after waxing the surface, the microcapsule prepared can further improve its slow-release performance.On the basis of study on the accelerator microcapsule, a cement slurry system with low density, low initial consistency, short dens??d time, good sealing and high strength is made up. The complexity of oil and gas wells for exploration and development of a new cementing technology to support.