Publications

The use of expanding cement for improving the sealing efficacy of annulus cementing has been considered for a long time as a possible solution to existing problems (Ghofrani and Plack, 1993). CaO and MgO swelling cements without additives exhibit real matrix expansion, sometimes up to 17 percent at a swelling additive content BWOC of 20 percent. A decrease in the swelling additive content results in lower expansion values. The right composition of a CaO- swelling cement recipe to be used within the temperature range up to 105oC presupposes the availability of appropriately reactive swelling agents and the right retarders. While different reactive calcium oxides are offered on the market, more reactive magnesium oxides are not available. The self-manufacture in laboratory scale of MgO has been conducted and processes of volumetric shrinkage of cements due to hydration as well as the effective mechanisms of MgO swelling cements are explained. Out of Canadian, Austrian and Turkeysh magnesite deposits in each case samples were taken.The samples were burned with grain size 0.5 - 1 mm at firing temperatures between 900 – 1500oC and at varying burning duration in the laboratory furnace. For comparison reasons a commercial soft burned MgO sample was re-burned under the same conditions. Different direct and indirect analysis procedures were examined in terms of its suitability for the qualitative and quantitative description of quicklime reactivity. The MgOs were examined with different methods: modified wet slaking curve (NLK), determination of the gross density by means of solid pycnometer, Scanning Electron Microscopy (SEM), determination of the net density by means of Hepycnometer, Positron Lifetime Spektroscopy (PALS), short wave length X-ray, Electron Spectroscopy for Chemical Analysis (ESCA) * Institute of Technology Bandung and determination of specific surface (BET). The test results confirmed that MgO-swelling cement recipe can be used at a temperature up to 250oC. Keyword: Expanding Cement, High Pressure High Temperature (HPHT) Cement Well, Swelling Cement