Investigate the effect of Sedimentary Environments and Diagenesis Processes on the Reservoir Quality of the Asmari Formation in Kupal field by Combining the Results of Seismic Sequence Stratigraphy, Petrophysical Evaluation, Seismic Attributes and Inversion

The purpose of the present study is to investigate the effect of sedimentary environments and diagenesis processes on the reservoir quality of the Asmari Formation in Kupal field by combining the results of seismic sequence stratigraphy, petrophysical evaluation, seismic attributes and the inversion of three-dimensional seismic data to determine more precisely the process of changes in the reservoir properties of zones 1 to 5 of the sequences of the carbonate part of the Asmari Formation. In this study, the inversion method was used to extract acoustic impedance from 3D seismic data by Hampson Russell software. There are different methods of inversion of seismic data, according to the available data and the conditions of the Kupal field, in this study, model-based inversion is chosen due to its higher accuracy and separation power. The special aim of this article is to determine the changes in the reservoir properties of the Asmari formation by combining the results of the inversion of seismic data and seismic indicators with the results of sedimentological studies, sequence stratigraphy. According to sequence of stratigraphic studies, Asmari Formation has three sequences. The lower sequence is in the sandstone section and the middle and upper sequences are in the carbonate section. According to petrophysical studies, Asmari reservoir has 7 main zones. Zones 1 to 5 are in the upper and middle sequences of the carbonate section, zones 6 and 7 are in the lower sequence of the sandstone section. After matching the results of inversion with the results of sedimentology, the stratigraphic sequence was identified as the middle sequence, which includes zones 3, 4, and 5. It settled in a carbonate platform sedimentary environment. This sedimentary sequence is influenced by digenesis factors after deposition and the conditions of the sedimentary environment during deposition. Zones 3, 4, and 5 have sporadic changes in acoustic impedance indicators, layer thickness, and porosity. The most important factor of these changes can be due to the presence of mounds and reefs in these sediments. According to the dissolution or cementation of reefs, these zones may have high porosity and low impedance (dissolution) or low porosity and high impedance (cementation) in reefs. The final sequence of the Asmari formation, which includes zones 1 and 2, was deposited in the Sabkhai environment. This condition has caused primary or secondary porosity between the dolomite crystals. The changes in porosity and acoustic impedance and the amplitude of zones 1 and 2 are very small. Due to the low depth of the sedimentary basin, we see the activity of river systems in some places, which have caused erosion and deposition. The sediments of these rivers can have high porosity and low acoustic impedance. These sediments have high reservoir quality. The implications of this study suggest that in Maron and Aghajari fields are adjacent to the Kupal field and they have three-dimensional seismic data. Coincidentally, they can indicate a interpretation of three-dimensional seismic data and stratigraphic seismic sequence in these fields.