SPE Releases Technical Report Outlining Proposed Worst-Case Discharge Calculation Methods

The Report is a Resource for Oil Spill Response Planning

HOUSTON, USA (6 MAY 2015) – The Society of Petroleum Engineers (SPE) releases a technical report based on work done at a Worst-Case Discharge (WCD) Summit in March of 2014. The summit was attended by 68 subject matter experts with the goal of improving the methods of calculating and reporting WCD of oil or gas to the environment resulting from a loss of control (a blowout) during open-hole drilling.

The main purpose of a WCD calculation is to support oil spill response planning. It is not intended for well design, kill design, or casing design, but these processes are all integrally related. It may be the starting point for well containment planning, which may require additional alternate scenarios that may modify the total flow.

Trey Shaffer, SPE Health, Safety, Security, Environment and Social Responsibility Technical Director said, “WCD reporting is now part of the landscape of offshore regulatory requirements since Macondo in 2010. The past few years have been a period of learning and now the time is appropriate to take stock of the lessons learned and best practices, and discuss the way forward from both operator and regulatory standpoints.”

The SPE WCD Technical Report is a proposed approach incorporating early guidelines, issued in August 2010 and four years of operator experience with compliance and regulations. The first guidelines were published just four months after the Deepwater Horizon (Macondo) incident, by the SPE Gulf of Mexico Incident Response Task Force, the Offshore Operators Committee, and the Offshore Technology Research Center (a joint venture of University of Texas and Texas A&M).

Shaffer added, “All of this practical experience has led to a desire to establish a transparent process and to develop a consensus approach so that operators and regulators can have confidence that the methods employed are both consistent and reasonable.”

The technical report is based on US Department of Interior regulations and interpretation as of March 2014. Current US regulations require the WCD to be calculated from deterministic methods. Probabilistic modeling and statistical analysis are not currently acceptable in US regulatory framework.  Therefore, the summit consensus for calculating the WCD includes the following:

  • Explain and justify all calculation parameter values to ensure consistency and transparency;
  • Use the best technical estimate for each reservoir property, as assessed by the subsurface geoscience and engineering team using available known and/or analog data;
  • Conduct a parameter sensitivity analysis to identify the major variables and their impact on the WCD calculation;
  • Model the flowing scenario over the duration of the spill, i.e. the intervention time;
  • Assess each potential well location – the WCD will be determined by the planned well with the highest WCD flow rate.

To download the full report go to http://www.spe.org/publications/techreports.

About Society of Petroleum Engineers
The Society of Petroleum Engineers (SPE) is a not-for-profit professional association whose members are engaged in energy resources development and production. SPE serves more than 143,000 members in 147 countries worldwide. SPE is a key resource for technical knowledge related to the oil and gas exploration and production industry and provides services through its publications, events, training courses, and online resources at www.spe.org.