Tectonics
Mahnaz Sabahi; Ramazan Ramazani Omali; Masoumeh Kordi; Mohsen Dourandish
Abstract
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 ...
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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.
F. Khoshbakht; H. Memarian; M. Mohammadnia
Abstract
Natural fractures are the main factor which control hydraulic behavior of oil and gas reservoir in naturaly fractured reservoirs. Thus it is important to fully characterize these features in fractured reservoirs. Image logs are one of powerful tools in fracture study in wells. Image log is high ...
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Natural fractures are the main factor which control hydraulic behavior of oil and gas reservoir in naturaly fractured reservoirs. Thus it is important to fully characterize these features in fractured reservoirs. Image logs are one of powerful tools in fracture study in wells. Image log is high resolution “pseudo picture” of borehole wall which records properties of fractures. In present study, FMI (Formation Micro Scanner) of two wells located in the same structural setting of a naturally fractured carbonate are considered. Well A and B drilled through three formations (Asmari, Pabdeh and Gurpi) and fracture data of these formations were acquired from these wells. Both wells located in the same structural setting near each other. We compared fractures of each formation in well A with well B to find out similarity and dissimilarity of fractures occurd in the same formation in different wells. This study shows that density and orientation of bedding planes of well A is completely similar to well B. Density of open fractures of well A is totally different from well B but orientations of open fractures are same in two wells. Density and orientation of filled fractures of well A are similar to well B. Pattern of fractures of Asmari and Pabdeh formations are similar but in Gurpi fractures are different. Comparison of density of bedding planes and fractures show that high fracture frequency occurred in the thin beds, for example FMI show that laminar intervals of Pabdeh coincide with highly fractured intervals.
