Crude marker WTI has remained below $50/B for the last three weeks. So far at least, there is no sign of US producers trimming their plans to boost output over the coming months. The Permian shale oil basin remains their key investment focus. But they are keeping a wary eye on rising prices.

Latest data from the US government’s Energy Information Administration (EIA) shows that crude output averaged 9.314mn b/d over the week to 5 May, the highest figure since August 2015 and just over...