Facies architecture and basin development of the Qamchuqa succession, NE Iraq

Abstract

The Qamchuqa succession in this study is represented by the Upper Qamchuqa, Jawan, Upper Sarmord and Lower Qamchuqa formations which were deposited during the Early Aptian Late Albian within the Zagros foreland basin. Petrographic study and microfacies analysis enabled the recognition of six main paleoenvironments. These are the shallow restricted, shallow semi-restricted, shallow open marine, shoal, deep outer ramp and deep basinal environments. The study succession represents the deposition of four third-order cycles; these cycles were deposited during successive episodes of relative sea level rises and still stand. The Lower Qamchuqa basin in the study area stretched from the southwest to the northeast with its deepest parts with high rate of subsidence and accumulation located to the north near well Kirkuk-117 and in the center near Bi Hassan-13, Khabaz-5, Kirkuk-109, -130, -229, and −260; and to the Southeast in well Jambour-13 and −15. The Upper Sarmord depocenter was located in the northeast near well Taq taq-1, with the general direction of southwest–northeast. The rates of subsidence and accumulation were high, where accommodation rates matched accumulation rates. The Jawan basin is extended in the west of the studied area with two depocenters; the first is extended from Makhul oil fields to the Northern Bi Hassan oil fields and the second in the Northwestern part in well Najmah-29 and surrounding area. These areas were characterized by high rates of subsidence and accumulation. The Upper Qamchuqa basin stretched from Southwest to Northeast with its deepest parts located at wells Ajeel-8 and Jambour-13. The high thickness values in depocenters of the Upper Qamchuqa formation reflect the high rates of subsidence and accumulation.