The comparison of concentration and strike pattern of the Yortesha Anticline's surface and subsurface fractures, The Natural Gas Storage Field in The Central Iran Zone

In the past decade, several geophysical, geological and reservoir studies have been done on the Qom formation in the Yortesha field for injection and gas storage purposes. Qom formation in this field has a poor reservoir characteristic (low porosity and permeability); therefore the role of fractures for increasing permeability and improving reservoir quality is very important. In the current study, fractures’ concentration and strike patterns of the Qom and Upper Red formations as the carbonate reservoir and cap rock, respectively, have been investigated and compared in the Yortesha anticline and its adjacent anticlines (Davazdah Emam and Morreh) using surface and subsurface investigations. In order to achieve this goal, desert data gathering methods, remote sensing, and image log analysis have been used. Subsurface studies and interpretation of FMS and EMI image logs determined that fractures have also a secondary strike of NE-SW in addition to strike of NW-SE. Based on the FMS image log interpretation of well No. 2, three subsurface fracture sets have been identified with the strikes of N55E, N65E, and N15W as well as using the EMI log of well No. 4 shows the two dominant strike of N10E and S45E. The total 1852 specified fractures in the out crops of the Morreh and Davazdah Emam surface anticlines can lead to rose diagrams that show four fracture sets with the strikes of N10E, N45E, N80E, and S45E.