Interpretation of produced water analyses

Benefits

  • Identification of improvements in sampling and analysis procedures that can be made.
  • Identification of variations in formation water compositions (where they are present) can aid scale management and reservoir management, amongst other functions.
  • Understanding reactions occurring in the reservoir as a result of water injection, can aid scale management by:
    • Helping quantify the effect of reservoir reactions on produced water scaling risks.
    • Identifying the best natural tracers to use for monitoring injection water breakthrough and the injection water fraction in produced water.

Background

On fields where water is not being injected, only formation water will be produced (possibly with water condensed from co-produced hydrocarbons).  Where water is being injected, the produced water may be formation water (e.g. early field life), a mixture of formation water and injection water, or in some cases just injection water.

Produced water analyses may display variations in composition reflecting variations in injection water fraction, variations on formation water compositions, the effects of reservoir reactions on injection waters and, occasionally, artefacts of sampling and analysis procedures adopted.  With the support of geochemical and reactive transport modelling, we can interpret the trends in produced water compositions and provide information on the causes of these variations.

Where artefacts of sampling and analysis procedures are present we can provide recommendations for improvements to current procedures.

Where it is found that formation water compositions vary across the reservoir this information will have a number of direct applications for scale management and other functions.  Interpretation of the variations can also provide additional information on reservoir connectivity and fluid flow directions relevant to reservoir management.

By understanding the reactions occurring in the reservoir, we can:

  • Identify natural tracers which can be used to identify injection water breakthrough and to quantify the injection water fraction in the produced water.
  • Use the information to help quantify the effect of reservoir reactions on produced water scaling risks.
Produced water compositions – they may be very variable but they can carry much information about your reservoir and production from your wells
Produced water compositions – they may be very variable but they can carry important information about your reservoir and production from your wells