Improved deepwater cementing practices reduce NPT

Over a four-year period, during which some 42 wells were constructed by BP, processes were developed to improve cement slurry design and reduce Non-Productive Time (NPT) during cementing operations on deepwater wells. Cementing best practices have been followed for many years; however, not all of these are applicable to deepwater operations, especially for the riserless sections. This article will review the results of developing slurry design practices, temperature prediction/mud removal modeling, and Subsurface Release Plugs (SRP). The cement blend used can have a profound impact on cost, both in design and supply logistics. As deepwater operations move farther from shore bases, the application of a systems approach should be considered to cover all cement design needs. The challenges vary from shallow water flow potentials to high temperature and pressure. Both conventional and foamed cement slurries can be successfully used when properly designed and placed.

Vol. 228 No. 9

SPECIAL FOCUS: DEEPWATER TECHNOLOGY

Improved deepwater cementing practices reduce NPT

Slowing the pump rate reduces dart velocity before launching the bottom plug.

Richard F. Vargo Jr, James F. Heathman, Halliburton; Daryl S. Kellingray, Martin D. Ward, John M. Lummus, BP Exploration

Cementing best practices have been followed for many years; however, not all of these are applicable to deepwater operations, especially for the riserless sections. This article will review the results of developing slurry design practices, temperature prediction/mud removal modeling, and Subsurface Release Plugs (SRP).

The cement blend used can have a profound impact on cost, both in design and supply logistics. As deepwater operations move farther from shore bases, the application of a systems approach should be considered to cover all cement design needs. The challenges vary from shallow water flow potentials to high temperature and pressure. Both conventional and foamed cement slurries can be successfully used when properly designed and placed. Placement design should include understanding the drilling fluid’s static gel development behavior.

Although it is accepted that conventional circulating temperature estimates are not appropriate for use in deep water, the use of alternatives is not always practiced. Over the course of this project, this operator realized better cement slurry performance and lower slurry costs following the correct use of wellbore thermal simulators. Attention to detail resulted in lower slurry costs while achieving improved performance, as measured by casing shoe integrity.

Real-time monitoring and detailed pressure analysis were used to manage cementing operations and the correct application of SRP. Feedback from operators and service tool personnel has resulted in improved performance, as measured through reduced NPT and construction costs. These processes have resulted in a 100% success rate, compared to the previous 74% success rate.


	This article was adapted from a professional society paper for which World Oil was granted the right to print one time only. Therefore, to review the article, you should refer to the actual World Oil magazine in which it originally appeared.

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