The invariance ratio in isoheptanes: a powerful tool for oil–oil correlation in the Tertiary Niger Delta, Nigeria

The invariance in isoheptanes, seen in all primary oils, proves a powerful tool for oil–oil correlation in Tertiary Niger Delta oils, Nigeria. Thirty-five oils from two fields in the offshore Eastern Niger Delta separate cleanly into two groups based on distinctions in their invariance ratios K1 and two ring preference ratios (P3/N2 and CPs/CHs). One of the two Eastern Niger Delta oil sets compares well to 51 previously analyzed oils from the Western Niger Delta. The other set, however, remained distinct, implicating at least two very different sources for the Tertiary Niger Delta oil system.