Guest editorial The market for abandonment and decommissioning has undoubtedly grown over the past 5 years, as the boom of the 1970s and 1980s makes way for the first tranche of major decommissioning projects. From the smaller plug-and-abandonment campaigns in the Gulf of Mexico to the mighty Brent field in the UK North Sea, we have reached a milestone in our industry that feels alien to many of us. Having spent the majority of my 25-year career focused on exploration and appraisal, this has not been lost on me. A large proportion of those years were committed to the complex challenges associated with high-production land wells in the Middle East, offshore, deep water, as well as subsea projects in the Gulf of Mexico, Brazil, Asia, and Australia. However, as we continue to optimize recovery from mature fields, it has opened my eyes to the prospect of decommissioning from a challenge that was “on the horizon” to one that is quite literally on our doorstep. Government legislation has played a large part in this refocus, as recent changes drive specific technical and time requirements. For example, the US Bureau of Safety and Environmental Enforcement (BSEE) says that, under its Idle Iron Program, wells or platforms no longer in use must be decom-missioned within 5 years. As of 2015, this amounted to 535 eligible platforms and rising. While Europe’s legislation is different, Oil and Gas UK’s recent Decommissioning Insight 2016 report estimated that over the next decade, 186 projects are forecast for decommissioning, including 1,800 wells. To deliver this in a safe and economic way, we need to accept and embrace decommissioning as a serious industry challenge. Many people still perceive or talk about decommissioning in a negative way, as if it marks the immediate death of our industry. Setting aside the fact we are still making new discoveries, it has taken us many decades to explore for oil and will take many more to abandon our wells and decommission infrastructure. A study from the late 1990s estimated the cost of decommissioning the world’s 6,500 offshore platforms at between USD 29–40 billion over 30 years (Pittard 1997). However, this now seems a huge underestimation, given that the UK alone is forecasting a cost of nearly GBP 18 billion/USD 22 billion over 10 years (Oil and Gas UK 2016). Either way, the figures are extremely compelling.