The mineralogy and textural characteristics of a section of Gondo Well, Niger Delta, Nigeria.

The sands of the Agbada Formation were studied to deduce their mineralogy, tectonic provenance, and textural and reservoir characteristics. The study is based on 40 DITCH CUTTING SAMPLES retrieved from a section of a Gondo well in the Niger Delta Basin. Thin sections were prepared from the samples taken at inconsistent intervals (feet) from the core samples of the well. The study, which was based on quantitative analysis of the detrital minerals, shows that the clastic sediments (mostly sand and tiny sandstones) are predominantly made up of quartz, with the minor occurrence of a variety of feldspar and rock fragments, as revealed in the modal analysis of the results. Among the detrital framework, quartz constitutes about 50%, feldspar 22%, and lithic fragments 29%. The dominance of quartz grains with few feldspars and generally medium- to fine-grain, poorly to moderately sorted sand suggests matured sediments. The QFL (Quartz-feldspar-lithic fragments) ternary diagrams indicate that the sandstones were derived from recycled or quartzose source rocks. This possibly revealed that most of the sandstones might have been derived from the weathering and erosion of igneous and metamorphic rocks. Few polycrystalline quartz occur, which suggests that the sands of the Agbada Formation are just being subjected to diagenesis. Additionally, the information deduced from the provenance chart suggests that the majority of the sediments come from an arid environment, which is practically demonstrated by the present-day linkage of the River Niger with the Futajalon highland, a semi-arid region. Based on the few clay minerals and the textural characteristics of the sediments, it can be concluded that the well has a fair reservoir quality that will not significantly favor hydrocarbon exploration. Keywords: Petrographic Analysis, Provenance, Reservoir Characteristics, Agbada Formation.