Earth, barometric and ocean tide effects have been observed for many years, principally in hydrogeological work. During testing of wells in the Timor Sea we have observed ocean tide effects in the reservoir with an amplitude of ~ 0.07 bar (1 psi) about 70 times larger than earth or barometric tide effects.

This paper has two aims: to provide an overview of analytical interpretation of tidal effects from a petroleum engineering viewpoint and second, based upon our simulations and observations, to propose that in addition to previous methods of interpretation the phase shift of ocean tide effects can be used to gain an insight into the presence of major reservoir heterogeneities, particularly fluid contacts.

There is a need for more field data and further investigations, however we believe we have demonstrated the existence of a useful and previously unused aspect of pressure measurement in offshore wells.

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