Abstarct: Studies show that the cement rock compressive strength development cannot be accounted as a major factor in increasing cement strength in order to prevent the cement coat damage and in more critical conditions, casing collapse and also improving cement durability in the lifetime of the well for the establishment of proper bonding between laxyers. Conventional cements with high compressive strength were unable to solve the Aforementioned problems. In most cases, novel cement systems with density range of 120-140 Pcf with reduced Young’s Modulus are used to withstand induced stresses. Such solutions can be run successfully, however, in many cases higher density cement systems in range of 140-155 Pcf with 3% volumetric expansion capacity are required due to the pressure deployment in high pressure formations like Gachsaran in Marun oilfield. This is also the case for many high pressure oilfields across the world. Therefore, research and investigation is essential for the design of a cement with flexibility, high volumetric expansion, low young’s modulus, high poisson ratio and density to prevent casing collapse in Marun oilfield. To this end, many additives such as hidense, gilsonite, Fe2O3 and silica nanoparticles and elastomers have been examined and many tests carried out for increasing elasticity and volumetric expansion of special cement systems. According to the test results, with increased hidense concentration in cement slurry compositions, and keeping other parameters constant, it was found that this type of additive is ineffective on the cement elastic property, hence gilsonite was selected as the next candidate. Although this additive was effective on the cement rock flexibility in minus scales, but its very low density and severe reduction in slurry weight is opposed to the dissertation goals. Hence, we had no choice but to remove this additive. In the next stage, domestic manufactured silica and Fe2O3 nanoparticles were used. According to the investigations, with increasing concentration of Fe2O3 nanoparticles up to 9% bwoc, poisson ratio was increased up to 0.22 but in higher concentrations it has no significant effect on the cement rock volumetric expansion and also prevents the cement from reaching the least compressive strength required. Silica nanoparticles were proposed as the solution to this problem. baxsed on the long mixing times and the reverse effect on poisson ratio and young’s modulus, the tests were terminated after 3% concentration of this additive. In the end, replacing with elastomer additive and increasing its concentration up to 12% bwoc, it was observed that the elastic properties of the cement were improved. In the next step, with decreasing the size of the elastomer particles to Mesh No 70, the optimum cement slurry formulation regarding to the real problematic conditions of the Marun oilfield was designed. With regard to the slurry designs carried out, slurry 2 was selected as the best formulation design for the cementing of the Marun oilfield wells. According to the test results; this slurry has 45 seconds mixing time, slurry density of 115 Pcf, very good rheological properties with no settling, 55 ml fluid loss, volumetric expansion of 2.7 %, compressive strength of 1750 Psi during 24 hours¬, 1.7 GPa young’s modulus, 0.29 poisson ratio, 184 minutes right angle set thickening time, gel strength transition time of less than 25 minutes (125 to 250 Pa) and acceptable against gas migration.