SPE APOGCE conference preview – Wheatstone and Iago Fields Interference Testing: Execution and Interpretation with Ensemble Variance Analysis

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Abstract

The Wheatstone Project is an LNG development located in Western Australia, incorporating the Chevron Australia operated Wheatstone and Iago fields and third-party gas fields. Production commenced in mid-2017. The start-up of the Wheatstone and Iago fields was a unique opportunity to acquire reservoir surveillance information that was able to provide valuable reservoir insights. A key component of the analysis was the observation of pressure interference between wells from the initial well clean-ups. The design of the well clean-up sequence, discussed in a previous paper (Flett & Connell, 2019) was influenced by operational guidelines and the application of Ensemble Variance Analysis to determine an optimised start-up strategy for interference testing with the objective of reducing subsurface uncertainties.

The well clean-up sequence was executed safely and achieved the reservoir surveillance and operational objectives of the start-up program. Flexibility in the optimised well clean-up sequence allowed changes to the start-up strategy in response to changing operating conditions, without impacting the reservoir surveillance objectives.

High quality pressure interference data was acquired, enabling clear determination of zonal reservoir connectivity within the Wheatstone and Iago reservoirs. Interpretation of pressure interference results with reservoir models, incorporating Ensemble Variance Analysis led to a change in approach for initial history matching and revision of static and dynamic model development for Wheatstone and Iago fields.

Fig. 1—A) Location of Wheatstone and Iago fields, B) location of development wells and subsea production lines to the Wheatstone Platform