BIOSTRATIGRAPHY OF KHASIB FORMATION BY USING PLANKTONIC FORAMINIFERA AT SELECTED WELLS IN RUMILA OIL FIELD, SOUTHERN IRAQ
Khasib Formation is one of the important formations in Iraq due to the wide spread and varying in thicknesses. In some oilfields like West Qurna, Khasib Formation represents a production reservoir. In this study, the selected fossils at this formation are studied precisely and ignored some species. In Rumaila Oilfield, eight oil wells were taken and fifty-five samples from planktonic foraminifera were collected, analyzed and identified. Twelve species belong to seven genera were chosen and diagnosed accurately, these are Marginotruncana scheegansi, Marginotruncana renzi, Clavihedbergella simplex, Whiteinella archeocretacea, Praeglobotruncana algeriana, Globotruncana imbricate, Globotruncana sigali, Heterohelix Russi, Heterohelix globulosa, Planoheterohelix globulosa, Heterohelix navarroensis, Heterohelix moreman. Marginotruncana scheegansi Assemblages Zone was suggested to the studied section. It corresponds with the regional zone of sigal (1977). The results of the present study showed that the formation age is Turonian-Coniacian, and there is no evidence of the Campanian age of Khasib Formation as mentioned in the previous studies.