This link is to a conference held in Edinburgh on the global challenges of effective water management in the oil field.
The role of the regulator was stressed in reservoir preparation to maximize economic recovery factors and in compliance with environmental laws.
With respect to the regulation of marine discharges of produced water, Michael Hannan of the UK department of Energy and Climate Change «encouraged operators to keep abreast of future risk-based discharges limits being proposed by OSPAR - the Northeast Atlantic Convention that sets limits for marine discharges.»
This appears to constitute another example of regulation translating environmental externality from water use into internalised business costs for energy operators.
The CEPMLP could be interested in this.