An operator spudded an extreme high-pressure/high-temperature (eHP/HT) well in the Mediterranean Sea, offshore Egypt, in 2012. To achieve the well objectives, it was necessary to set 28-in. surface casing at 1183 m, which was the deepest casing point used for such a large casing size in the offshore Mediterranean. The depth and size of the hole required presented numerous challenges, including but not limited to managing the variable deck load, hole stability during long casing running operations, logistic challenges for fluids resulting from significant washouts, etc.

One of the main challenges was related to achieving zonal isolation objectives for this section. These objectives were to cover the casing shoe with good quality cement and to achieve zonal isolation at the seabed and top of casing to help avoid future unexpected shallow flows to the surface. Meeting both of the objectives was paramount for resuming further operations. Typically, both of these objectives can be achieved in a single stage using lead and tail slurries. However, because of the long hole section and significant washouts (up to 300%), bringing cement up to the seabed would require pumping approximately 4,400 bbl of lead slurry and 380 bbl of tail slurry, which is equivalent to approximately 11,700 ft3 (500 MT) of dry cement, and 16 hr of cement pumping time.

To help mitigate the risks associated with a single-stage operation, it was decided to perform the job in two different stages. The first stage was designed to isolate the casing shoe and lower sand body by performing a lead and tail primary cement job. The second stage was a liner top squeeze. This was a multistage operation using several cement types of various particle sizes. The top of the liner was successfully squeezed, and the objectives of the cementing operation were met.

This paper describes the challenges experienced and solution for completing the cementing job, which could be valuable for designing similar offshore high-pressure/high-temperature (HP/HT) wells.

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