One of the last exploratory frontiers offshore, where some of the biggest reservoirs have been found in late days, are the ultra deepwater areas of the Gulf of Mexico, in the Mexican side. Several methods and lessons learnt have been produced during the Exploratory Campaign of these waters, becoming the massive salt formations, one of the major challenges faced, not only for drilling methods and techniques, but for zonal isolation in general terms, related to cementing operations.
Cementing jobs executed in salt environments require cement slurries with specific concentrations of salt in order to avoid the acceleration/retarder effect of thickening time on the cement slurry due to formation salt incorporated during fluids placement in the annular space, and to avoid the dissolution of natural salt formation. Likewise compressive strength development must be capable of mitigating the effects of salt cuttings on the casing that isolates the zone to ensure the integrity of the section.
Salt is commonly classified as:
Magnesium salts – regular movement
Halite – low movement
Carbonates – without movement
This paper includes lab tests to determine the physical and chemical properties of cement slurries with different concentrations of sodium chloride (NaCl) and potassium chloride (KCl). A deep analysis was performed with these slurries when in contact with salt formations, determining the dissolution effect of salt in cement slurries. Lab tests were performed with Halite samples from ultradeepwater wells in the Northern Region of the Gulf of Mexico.