عنوان مقاله [English]
In oil and gas wells, the quality of cementation behind the casing and liners has a significant role in maintaining safe production and reducing costs due to possible future repairs of the wells. Proper cementing prevents interlayer flows behind the casing, reduces the severity of corrosion of the outer surface of casing, prevents leakage of the annulus and the edge of liners, prevents water movement from deep to the upper reservoir zones of the space be-hind the pipes and prevents subsidence due to the infiltration of water from deep into the surface layers of the earth. The results of this study show that apart from the method of cementing operations and cement compositions, the property of rock and fluid also affects the quality of cementation. In drilled wells of Khangiran gas field, mainly the quality of cementation in certain zones of sedimentary formations is inappropriate. In this study, after applying petrophysical zoning on the formations of Khangiran field, first the sub-zones in which the quality of cementation is usually low were identified. Such as zone3 of Abderaz Formatiom. Then, the possible reasons for this event were investigated. For example, Existence of high permeability in zone1 of kalat formation. and finally, some suggested solutions to prevent the recurrence of this phenomenon in drilling future wells were presented. Such as changing the depth of casing point. The most important zones in which cementing are weak include porous and permeable zones and gas zones.