High-Resolution Sequence Stratigraphy of the Mauddud Formation Southern Iraq

Abstract

Inner ramp carbonate and dolomitic limestone made up the late Albian Mauddud reservoir in Iraq. An age estimate for the Mauddud Formation is late Albian to early Cenomanian, with it overlying the Nahr-Umr Formation and underlying the Ahmadi Formation. The integration of microfacies with wireline logging data to predict the high resolution of the sequence stratigraphy framework. The microfacies description included more than 150 thin sections that covered the study area in southern Iraq. That results in five main microfacies. There are divided into eleven submicrofacies, as a result, for the microfacies, the depositional environment is gradual, from mid-ramp to shallow open marine, shoal-restricted lagoon. The study divided the formation into four orders of sequence stratigraphy: MSL1, MSL2, MSL3, and MSL4. The study includes identifying the maximum flooding surface (K110), which is identified as the original transgression in sea level that covered Arabian Plate. MSL1 represents the lower part of formation and evidence of environmental change to shall the marine environment with argillaceous limestone. The maximum flooding surface (K110) is signifying the deepest depositional environment (mid-ramp). Also, the study marked three marine flooding surfaces by changes as increased gamma ray and density logs values, whilst the highstand system reflects decreasing in logs values, This change was used in conjunction with microfacies data to construct the sedimentological environments that led to the documentation of the Mauddud high-resolution sequence stratigraphy framework.