Cementing Technology of a Self-Healing Cement Slurry in the Carbonate Formations in the Well Manshen 1

During the drilling of the fractured carbonate formation in the third spud of Well Manshen 1, serious problems were encountered such as severe sloughing of the borehole wall, irregular hole diameters, active oil and gas shows of the target layer, low displacement efficiency during tri-liner cementing, and prominent contradiction between pressure stabilization and lost circulation control. In order to ensure the safe and smooth cementing operation of the third spud of the well and guarantee the cementing quality, a self-healing cement slurry was prepared by self-healing agent BCY-200S and cement additives with good compatibility with the agent. In addition, considering that lost circulation occurred easily when running casing and cementing, the “forward injection and reverse squeeze” technique was adopted on the basis of accurately determining the position of the leakage layer according to the previous construction situation. After the application of the self-healing cement slurry and the “forward injection and reverse squeeze” cementing technique to the carbonate formation in the third spud of Well Manshen 1, the cementing operation was safe and smooth. It not only sealed the pay zone but also avoided the annular channeling in the later operation. The research and practice demonstrated that the self-healing cement could automatically repair the microfractures after encountering oil and gas. In this way, they could achieve the goal of sealing the pay zone and solving the problems of annular pressure and interlayer cross-flow in the high-pressure natural gas wells of the Tarim Oilfield.