Abstract

Pneumatic conveying is a material transportation process used on nearly every offshore rig, in which bulk particulate materials are moved over horizontal and vertical distances within a piping system with the help of an air stream. Using either positive or negative pressure of air or other gases, the material to be transported is forced through pipes and finally separated from the carrier gas and deposited at the desired destination. This mode of bulk solid transportation is efficient compared to other modes of transportation because of the flexibility of installation and application on the rigs. Although pneumatic conveying has seen increased use on drilling rigs, there are still many major problems hampering its employment in a wider range of conveying applications like high energy consumption, excessive product degradation and system erosion, unstable plugging phenomena, severe pipe vibration and repeated blockages. Further, the lack of simple procedures for the selection of an optimal system, thus use of sub-optimal system are major problems in pneumatic transport system design and rig applications.

This paper presents a scientific investigation aiming to design and optimise offshore bulk transfer systems for handling of weighting materials like barite, clay type materials like bentonite and oil well cements. The approach is based on a scaling-up technique involved with pilot scale testing. Test procedures, relevant theories on gas-solid two phase flow in pneumatic transfer and results are presented in the paper. Finally, a detailed procedure on how to optimise bulk transfer on drilling rigs is presented.

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