Hydrocarbon potential of the Meso-Cenozoic Turkana Depression, northern Kenya. I. Reservoirs: depositional environments, diagenetic characteristics, and source rock–reservoir relationships

摘要: Abstract Major oil exploration efforts started in the 70s Meso-Cenozoic Anza Rift and Cenozoic Turkana Depression of northern Kenya. Thick piles fluvio-lacustrine sandstones shales infill these different rift basins. West Lake Turkana, Auwerwer/Lomerimong Formation is part Palaeogene–middle Miocene age, 7 km-thick Lokichar half-graben. East 220 m-thick Sera Iltomia possible late Mesozoic–basal Palaeocene comprises mudstones with conglomeratic layers. The poorly dated may represent either early phase African rifting Kenya or Rift. two formations exhibit sediment sources consequent reservoir quality. are immature basement-derived. While clastic material from section originated both volcanic basement terrains. Palaeocurrent data for basement-derived suggest a source to south south-east Turkana. volcanic-derived rocks forming south-southeast Basin, linked lower Samburu Basalts Formation. Evidence significant burial diagenesis absent both. In sandstones, calcite–analcite precipitation calcite cementation significantly reduced porosity initial values 40–45% which ranges up 15%. diagenetic events recorded by calcite, quartz kaolin cements. Quartz overgrowths local phenomena, did not induce reduction. some cases, completely occluded porosity, but other cases it has helped preserve limiting mechanical compaction. This resulted higher (up 33%) than Lomerimong better potential form reservoirs good Comparison encountered wells demonstrate that volcaniclastic-rich more frequently affected pore rather arkosic-type sandstones. complex stratigraphic structural organization Depression/Anza system illustrates variability source, reservoir–source rock relationships when exploring continental systems.