Palynology, palynofacies and maturation of sediments from mvule # 1 well, tanzania

The Cretaceous strata of the Mvule # 1 well from the Deep Offshore Basin of Tanzania contain large amount of shale and laminated mudstone, which under favourable conditions may be possible potential source rocks for hydrocarbons. This study examines hundred samples from early to late Cretaceous age by means of total organic carbon (TOC) content, palynofacies analysis and thermal maturities. These analyses have been performed to determine the hydrocarbon source rock potential, kerogen type, maturity level of the source rocks and to provide the biostratigraphic framework of these Cretaceous sediments. The organic richness from Mvule # 1 well (TOC - all in wt %) ranges from 1.0% - 3.4%. Palynofacies particles represent mixed macerals with clear higher abundance of marine influenced and black wood materials inferring marine depositional environments under oxygen-deficient bottom water. Four palynofacies zones have been recognised and presented here. Palynomaceral components from Mvule # 1 well are characterised by kerogen type II and III respectively. Vitrinite reflectance measurements of this well range from 0.7% - 1.6% Rv indicating maturity levels that encompass the entire oil and gas window. Preservation of palynomorphs is relatively poor to well preserve. This paper presents fifty-two species recorded from a total of thirty cutting samples ranging from interval 3700m - 4800m with the exceptional samples (ranging from 4150 - 4800m) that yielded moderate to good preserved palynomorphs assemblages for identification. The studied sections of the Mvule # 1 well contain a distinct palynological association dominated by abundance species including Classopollis classoides, Criboperidinium muderongense, Pterodinium cingulatum, Spiniferites twistringensis and Subtilisphera perlucida. Common species such as Exesipollenites tumulus, Sepispinula huguoniotii, Litosphaeridium siphoniphorum, Dinopterygium tuberculatum, Odontochitina operculatum, and Cyclonephelium sp., were also present, including rare species assemblages of Adnatosphaeridium tutulosum, Hapocysta peridictya and Florentinia mantelii.