PALYNOFACIES AND THERMAL MATURITY ANALYSIS OF BZ-1 AND BZ-2 WELLS, NIGER DELTA BASIN, NIGERIA

Résumé

The palynofacies and thermal maturity analysis have been carried out on one hundred and twenty composited ditch cuttings samples from BZ-1 and BZ-2 wells, offshore Niger Delta, Nigeria. The hydrocarbon potential of these sediments recovered from both wells were estimated on the basis of palynofacies analysis and thermal alteration index (TAI) values based on the palynomorphs (spore or pollen) colouration. The palynofacies analysis of the two wells reveals rich organic matter preservation, with amorphous organic matter and phytoclasts constituting the bulk of the total organic matter and low palynomorphs. The relative ratio and distribution of the palynofacies across the wells shows that the formation is gas laden and very little oil prospect. The thermal maturity deduced from the optical examination of the organic matter revealed that well BZ-1 sediments are immature while those of well BZ-2 are immature to slightly mature (TAI between - 2 and + 2 and SCI between 3 and 5).The lithological description of the analyzed sections of both wells
revealed a clastic sequence composed of alternating sand and shale sequences with accessory shell fragments, carbonaceous detritus, ferruginous materials, mica flakes, pyrites and rare glauconite