Architectural characterization of carbonate tidal channels in the Mishrif formation, Southeastern Iraq

For a better understanding of the strong heterogeneities of the Mishrif Formation in the H Oilfield of southeast Iraq, the characterization of the carbonate architectures has become one of the key research departments of carbonate rocks. This study aims to reveal the architecture and controlling factors of the carbonate tidal channels in the MB1-2B sub-layer of the Mishrif Formation in response to the delineation of the tidal channels that have hydrocarbon potential. Three architectural elements and three architectural boundaries of the tidal channels were identified by interpreting the cores, well-logging, seismic, and analytical data. The results show that: (1) the architecture characteristics of tidal channels are mainly migrating type in the downstream zone, the side of concave bank of the tidal channels is usually filled with relatively coarse-grained grainstone; (2) the architecture characteristics of tidal channels are mainly swinging type in the upstream zone, showing the high porosity and permeability; (3) the architecture characteristics of tidal channels are mainly vertical-accretion type in the mid-regions, indicating the instantaneous current reversals and high geographical position. This analysis demonstrates that the best reservoir quality within the tidal channels is located in the bend of the tidal channel near the inner lagoon and open sea, it provides the geological models for later exploration and development in the Mishrif Formation.