Development of New Oil Well Cement Retarder

In cementing a long open section well with big temperature differences, overtreatment or inadequate treatment of the cement slurry with retarders at high temperature high pressure will cause the thickening time of the cement slurry to shorten or change irregularly. After the cementing job, the retarding of the top of a long cementing section will cause gas channeling and failure of the sealing integrity of the cement sheath. Through optimized orthogonal experiment, a high temperature organic retarder was developed. By hybridizing an organic material and an inorganic material, and designing a layered structure, the organic material can be intercalated into or bonded with the surfaces of the inorganic material. The cement slurry in the cementing operation will experience a low temperature – high temperature – low temperature process, during which the spacing between the layers of the inorganic material will change with the process. At low temperatures, the inorganic material will dominate the strengthening action, while at high temperatures, the organic material dominates the retarding action. Two inorganic strengthening materials, one is a layered graphene, and the other a double electron layered hydrotalcite, were selected for developing two kinds of new oil well cement retarders. The graphene retarder has good adaptability, it is stable at 150 ℃, and its 72 h strength at 110 ℃ temperature difference is greater than 7 MPa. The double electron layered hydrotalcite is also stable at 150 ℃. Cement slurries treated with the hydrotalcite retarder have rheology that is easy to adjust, and the initial strength develops fast, but the late strength development is not as good as that of the graphene retarder. These retarders can be produced with simple techniques, the raw materials are easy to obtain, and therefore, will have broad promotion and application prospects.