Seismic geomorphology and stratigraphic trap analyses of the Lower Cretaceous siliciclastic reservoir in the Kopeh Dagh-Amu Darya Basin

Abstract

Lower Cretaceous Shurijeh-Shatlyk Formations host some of the main reservoirs in the Kopeh Dagh-Amu Darya Basin. Exploration in this area so far has focused on the development of structural traps, but recognition of stratigraphic traps in this area is of increasing importance. Integration of 3D seismic data with borehole data from thirteen wells and five outcrop sections was used to identify potential reservoir intervals and survey the hydrocarbon trap types in the East Kopeh Dagh Foldbelt (NE Iran). Analyses of horizontal slices indicated that the lower Shurijeh was deposited in a braided fluvial system. Generally, three types of channel were identified in the lower Shurijeh Formation: type 1, which is low-sinuosity channels interpreted to be filled with non-reservoir fine-grained facies; type 2, which is a moderately sinuous sand-filled channel with good prospectively; and type 3, which is narrow, high sinuosity channel filled with fine-grained sediments. Results indicate that upper Shurijeh-Shatlyk Formations were deposited in fluvial to delta and shallow marine environments. The identified delta forms the second reservoir zone in the Khangiran Field. Study of the stratigraphic aspects of the Shurijeh succession indicates that both lower and upper Shurijeh reservoirs are stratigraphic reservoir traps that improved during folding.

Stratigraphic model of a Middle-Late Jurassic carbonate system (Mozduran Ridge, Kopet Dagh area, NE Iran)

“…It is characterised by siliciclastic red beds deposited in fluvial to shallow-marine environments (Fig. 3; Hosseinyar et al, 2019). Some authors (e.g., Aghaei et al, 2018;Kadivar et al, 2017) assumed the boundary between the Mozduran and Shurijeh formations to be a paraconformity, although the contact is transitional in some areas such as Kardeh area (Fig.…”