Sedimentary Types, Characteristics and Genesis of Carbonate Platform Tidal Channel in M Formation of a Oilfield in the Middle East

The tidal channel is a special deposition of carbonate platform, which has a significant impact on the effect of water injection development. Based on the data of seismic, logging, core, cast thin section and analytical test, the types and characteristics of tidal channels in M Formation of A oilfield in the Middle East are studied. The lithology, electrical and physical properties are comprehensively compared, and the genetic analysis of various tidal channels and their influences on development are clarified. It is showed that three types of tidal channels are developed in the study area: intertidal tidal channel in tidal flat, inter-shoal tidal channel in restricted platform and incision tidal channel in weakly rimmed platform. The intertidal tidal channel is mainly packstone, the grain size becomes finer upward. The logging curve is finger-shaped, and it is mostly serpentine in seismic. This type of tidal channel is formed by the tidal effect in the tidal flat, which is a medium porosity and medium-low permeability reservoir. The inter-shoal tidal channel is mainly grainstone, and multi-period tidal channels are vertically superimposed. The logging curve is bell-shaped or box-shaped, and it is curved in seismic. This type of tidal channel is mostly formed in the process of transgression, which is a medium-high porosity and medium-high permeability reservoir with high productivity and easy to breakthrough in water injection. The incision tidal channel shows a three-stage sedimentary sequence of bottom packstone-middle mudstone-top packstone. The logging curve is micro-tooth bell-shaped, and it is striped with mutational boundary in seismic. This type of tidal channel is formed by the superposition of sedimentation, diagenesis and small fault in the layer, which is a low porosity and low permeability non-reservoir. Tidal channel sedimentations are widely distributed in the Middle East. The above research has guiding significance for the development of similar reservoirs.