عنوان مقاله [English]
In this study, the causes of the gas migration through the cement slurry of a seven-inch annulus of a well in Khangiran gas field as a case study are studied. Moreover, this study intends to propose practical solutions to prevent or at least decrease the problem. The quality and life time of the used cement sheath in the well is studied and the main causes of the gas migration are determined. The cement recipe is evaluated by new scientific methods and all the design parameters are evaluated, so that a new cement recipe using new cement additives and new design techniques replaces the traditional recipe and prevent gas migration. The proposed slurry has improved properties, including shorter transition time, less dynamic fluid loss, less porosity and permeability of cement stone, less free water, and higher compressive strength. It should be noted that the best way to solve the gas migration problem is the prevention and once the migration starts, it is almost impossible to stop it.
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