The Amu Darya basin

located in northeastern Turkmenistan

is one of the most important petroliferous basins in central Asia.Three third-order shallowing-upward stratigraphic sequences

each of which is composed of two system tracts (transgressive system tract and highstand system tract)

were recognized in the basin based on analyses of core observation

logging and seismic data.A sedimentology study of the Calov-Oxfordian carbonate platform reservoirs in the area reveals that there are six facies:evaporate platform

restricted platform

open platform

platform margin reef

gentle slope and basin.Among them

the platform margin reef and gentle slope reef flat are considered potential reservoirs for play fairways.The reservoirs are mostly rudist bivalve reef limestone and all sorts of grain limestones.Primary pores are well preserved and fracture-pore networks are common in the reservoirs.It is suggested that the distribution of reservoirs in the platform margin and the slope is obviously affected by controlling factors such as reef presence

distribution of shoal facies belts favorable for oil and gas accumulations

burial diagenesis.An understanding of these factors could be useful for oil and gas exploration activities in the future.