One of Algeria’s largest wet gas fields, In Amenas, enjoyed a record nine months in 2017, producing gas at a rate not seen for more than one quarter at a time over the past seven years.

The concession, operated by a consortium of the UK’s BP, Norway’s Statoil, and state energy company Sonatrach, produced an average 876mn cfd in the second quarter, the highest since Q1 2011 (see chart). This was followed by 837mn cfd in the third quarter, also higher than any quarter...