For reliable and durable design of the oil well the integrity of the stone cement under conditions of long-term exposure of formation waters corrosion should be provided. One of the effective methods for decreasing corrosion failure of cement stone is reducing the cement stone permeability by filling the space between the cement particles with sealants.
The article describes results of the study of cement stone with micro-cement resistance to corrosion aged in tanks with corrosive environment for two years. Because of the complex chemical composition of formation water it is not possible to describe the mechanism of rock destruction due to interference of individual ions, therefore, in practice the predominant type of corrosion is evaluated and studded on the single-component solutions in tanks and autoclaves. Samples were kept in tanks with 5% sodium chloride brine (NaCl), with 5% magnesium sulfate solution (MgSO4), with a 5% magnesium chloride solution (MgCl2), 5% sodium sulfate solution (Na2SO4) and formation water from Padunskie oilfield Perm region, and also in the tank with fresh water to benchmarks.
The results of two years laboratory studies show that the of the use of micro-cement to protect the well casing from the corrosive influence of sodium chloride and magnesium sulfate is expedience. The loss of samples strength with micro-cement and without it in sodium sulphate and sodium chloride solutions are almost the same, but cement stone with micro-cement is better in other equal conditions because of high-strength. It can be stated that the cement stone structure influences on its resistance to corrosion. The durability of the well casing could be increased by reducing the contact area between cement stone and corrosive environment and reducing the porosity and permeability.
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