Techbits: Integrated Water-Management Strategies Explored in Scotland (January 2010)
Authors: JPT staff _ 
Published: February 2015

Techbits

Edinburgh was the host of an SPE Applied Technology Workshop (ATW) dedicated to addressing the growing global challenges of effective water management in the oil field. Approximately 50 attendees representing production technologists and reservoir, processing, and petroleum engineers attended the ATW titled “Integrated Water Management: From Planning to Operations” and reviewed the latest technologies and strategies for maximizing value through improved water management at the field-planning and operational stages of an asset’s life cycle. 

Field-Planning Stage

Michael Hannan of the UK’s Department of Energy and Climate Change (DECC) first discussed the regulator’s role in reservoir preparation. He stressed that a regulator must ensure that an operator’s field plans include processes for maximizing economic recovery factors and for complying with environmental laws. The DECC expects operators to have a thorough understanding of voidage and sweep in the reservoir and design wells and facilities such that recovery can be maximized.  The operator’s plans should also be flexible enough to handle any unforeseen challenges associated with water handling. On the regulatory front for marine discharge of water, Hannan encouraged operators to keep abreast of future risk-based discharge limits being proposed by OSPAR—the north-east Atlantic convention that sets limits for marine discharges.

In his presentation titled “Planning Water Management,” Owen Vaughan of Apache Corporation said that despite the importance of planning in effective water management, conflict may arise within an organization because planning has different meanings for different people, depending on their background and experience. He also discussed the impact of data quality on the planning process, saying that for greenfield developments the quantity of data may be insufficient to allow a comprehensive water-injection plan to be developed. Conversely, for brownfields there may be such a volume of data that much of its quality may be questionable.

A discussion followed amongst the attendees on the pros and cons of produced water reinjection (PWRI) vs. water disposal. Participants were asked to take a stance on one of the methods with no middle ground and then list the relative benefits of their method. Among the benefits that the proponents of water disposal listed were the abundant availability of affordable technology to allow for disposal at sea and the lower capital and operating expenditures involved. Reinjection proponents cited the positive environ-mental image of injecting water back into the reservoir from which it came, as well as avoiding the need to chemically and mechanically clean the water for discharge.

Another reinjection debate followed on whether to inject water above or below the fracture gradient. Those supporting injection above the fracture gradient pointed to the benefits of an easier-to-manage injectivity index, lower capital expenses owing to smaller pumping equipment, and design advances allowing for better sweep control.  Those arguing for injection in the matrix highlighted the benefits of a better injection profile, a diminished risk of vertical fracture propagation, and lower injection pressures resulting in better vertical sweeps.