Source Rocks And Sorcerers: Decoding The Origin Of The Niger Delta Petroleum

Abstract

Against the present-day credo of the organic origin of petroleum, it may be difficult to believe that in the early days of the oil industry, the abiogenic (inorganic) origin of petroleum held sway. In 1877, Russian Scientist Mendeleev (of the Periodic Table fame) proposed that metal carbides deep within the earth reacted with water at high temperatures to form acetylene which subsequently condensed to form heavier hydrocarbons (as is readily demonstrated in the lab). CaC2 + 2H2O = C2H2 + Ca(OH)2 In 1890, Sokoloff propounded that `bitumina', originated from meteorites and that this petroleum was extruded from the earth's interior into the surface sediments. They were the first Sorcerers. Others (eg. Vernadsky, Kudryavtsev) were to follow with differing concepts of the Inorganic Origin of petroleum including Volcanic Origin Theory, Earthquake Outgassing, etc. Their views received great support from their peers (and still linger in some quarters!). Then came the period in the early 1900s when advances in the knowledge of the composition of petroleum saw the ascendancy of the Theory of Organic Origin. In particular, the discovery of the optical activity of petroleum (Walden, 1906) and of the presence of chlorophyll porphyrins (Treibs, 1934) confirmed the low temperature origin and history of petroleum and thus cemented the Organic Theory. Subsequently, the search for petroleum moved to the great sedimentary basins of the world. The successes scored seemed to put paid to the inorganic Theory. The organic Sorcerers seemed to have won. Or did they? In the 1990s, a new set of Sorcerers led by T. Gold reignited the Inorganic Theory. Largely supported by the state-owned Swedish electricity utility Vattenfall, he caused a deep well (6.5 km by 1997) to be drilled into the crystalline basement rocks in Sweden in search of predicted petroleum of inorganic origin but the outcome was a dry hole. Was that the end of the Inorganic Theory? Perhaps, not.