Cementing Casing Strings Across Salt Zones: An Overview of Global Best Practices

Abstract

Summary The global oil and gas industry is being challenged to increase production to meet the rising world energy demand. One of the key areas now being explored and developed to meet this demand are reserves below massive salt formations. To reach these reserves, it is necessary to drill through and case off the salt. Casing and cementing operations in such salt zones can pose particular challenges, ranging from the effect of salt dissolution on cement-slurry properties to the potential dangers presented by salt creep to the integrity of the well and the need to plan for contingencies for potential zones of overpressure or lost circulation. This paper examines and explores the challenges inherent with cementing across salt zones in the global arena. The current best practices for cementing casing strings across salt zones in some of the major subsalt basins of the world, including the North Sea and the Gulf of Mexico, are detailed and discussed. This work should assist those tasked with the construction of wells that have to penetrate significant salt formations to achieve their objectives safely and reliably.

Nanosilica functionalized to switch from dormant to active for gas migration mitigation in Portland cement

“…[1] The appropriate selection of the additives in cement slurries depends on the temperature and pressure profiles down the length of the well, the depth of the well, the geological formations that the slurry contacts, as well as the presence of gas, water, and oil in the different zones of the well. [2][3][4] The understanding of cement chemistry and cement additive chemistry is critically important for the appropriate design of oil well cements used in wells with these well-specific parameters. [5] Even with slurries which are well-engineered with commercially available cementing additives, gas migration problems have been found to occur which threaten zonal isolation.…”