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The AAPG/Datapages Combined Publications Database

Southeast Asia Petroleum Exploration Society (SEAPEX)


Offshore South East Asia Conference, 1996
Pages 291-305

Application of Precise Acoustic Positioning Techniques During the Development of the Liuhua Field in the South China Sea

John D. Hughes, Nigel C. Kelland


The paper describes the acoustic positioning techniques used during a multi-well subsea development in 310 metres water depth in the South China Sea. This included the accurate setting of the conductors for all 20 wells, the manifold piles and pipeline bases, and the production jumpers between each well, plus the installation of the clump weights for the flexible risers attached to the Floating Production System. Acoustic positioning played an important and comprehensive role in every phase and aspect of the seabed engineering work, significantly contributing to the overall success of the project. The emphasis of the paper is on the different acoustic techniques used to meet the high installation tolerances required to develop the field in an economical manner.

The ‘as-built’ well and pile locations were surveyed with a precision of ±0.15 metres, and a subsea gyro measured the conductor orientation to ±0.5 degrees accuracy. The ±0.3 metres elevation tolerance proved to be the most difficult, as the best available pressure sensors could only give an absolute depth accuracy no better than ±0.6 metres. However, using a differential technique, relative heights were established to better than ±0.1 metres. The riser clump weights were installed to within the required positioning tolerances of ±1.2 metres in a cost effective manner from an anchor handling vessel.

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