Drilling activity The results of oil and natural gas wells drilled and completed for each of the last three years were as follows: Exploratory and Appraisal Wells(1) Development Wells(1) Productive(2) Dry(3) Total Productive(2) Dry(3) Total Total Total Gross Net Gross Net Gross Net Gross Net Gross Net Gross Net Gross Net Year Ended December 31, 2017 Ghana Jubilee Unit . . . . . . . . . . . . — — — — — — — — — — — — — — TEN . . . . . . . . . . . . . . . . . — — — — — — — — — — — — — — Mauritania Block C8 . . . . . . . . . . . . . . — — 1 0.28 1 0.28 — — — — — — 1 0.28 Block C12 . . . . . . . . . . . . . — — 1 0.28 1 0.28 — — — — — — 1 0.28 Total . . . . . . . . . . . . . . . . . . — — 2 0.56 2 0.56 — — — — — — 2 0.56 Year Ended December 31, 2016 Ghana Jubilee Unit . . . . . . . . . . . . — — — — — — — — — — — — — — TEN . . . . . . . . . . . . . . . . . — — — — — — 7 1.19 — — 7 1.19 7 1.19 Total . . . . . . . . . . . . . . . . . . — — — — — — 7 1.19 — — 7 1.19 7 1.19 Year Ended December 31, 2015 Ghana Jubilee Unit . . . . . . . . . . . . — — — — — — 3 0.72 — — 3 0.72 3 0.72 TEN . . . . . . . . . . . . . . . . . — — — — — — 4 0.68 — — 4 0.68 4 0.68 Morocco (including Western Sahara) Cap Boujdour . . . . . . . . . . . — — 1 0.55 1 0.55 — — — — — — 1 0.55 Total . . . . . . . . . . . . . . . . . . — — 1 0.55 1 0.55 7 1.40 — — 7 1.40 8 1.95 (1) As of December 31, 2017, nine exploratory and appraisal wells have been excluded from the table until a determination is made if the wells have found proved reserves. Also excluded from the table are 14 development wells awaiting completion. These wells are shown as ‘‘Wells Suspended or Waiting on Completion’’ in the table below. (2) A productive well is an exploratory or development well found to be capable of producing either oil or natural gas in sufficient quantities to justify completion as an oil or natural gas producing well. Productive wells are included in the table in the year they were determined to be productive, as opposed to the year the well was drilled. (3) A dry well is an exploratory or development well that is not a productive well. Dry wells are included in the table in the year they were determined not to be a productive well, as opposed to the year the well was drilled. 31