Salt precipitation

From previous studies it was concluded that the impairment of gas production by salt precipitation is localised in the near well-bore region and perforations, and not deep in the reservoir (at least for the particular field studied in combination with the production age of the field). Main indicators of this are: 1) Salt particles accumulating in the well bore and up-hole, that are believed to originate from salt water produced at the perforations and not from salt particles transported in the pores. 2) The fact that production (at first instance) can be restored with a fresh water soak using relatively small amounts of water and relatively short soaking times (small penetration depth).

Proposed model
For a production environment, a relatively simple model is required, which predicts in a quantitative manner the following aspects:

  1. The onset and speed of production decline (boiling down to a prediction of the amount and location of salt precipitation and the subsequent effect on transport properties, that is permeability and capillary pressure curve).
  2. The relation between fresh water soak volume and washing frequency on production recoverage (boiling down to a prediction of speed and extent of water saturation and salt dissolution during fresh water soak, and subsequent water back production).

Project phases
Phase 1 – Salt precipitation predictions with existing reservoir models – FINISHED.
Phase 2: To develop precipitation and water wash models and validate on field data, using multi-scale model approach.
Phase 3: To develop on-line monitoring & optimisation functionality for Short Term (Real-Time) Production Optimisation.
Phase 4 – To develop an off-line tool for Field Development Planning.

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