M Javid; H Memarian; S.M Mazhari; R Zorofi; B Tokhmechi; F Khoshbakht
Abstract
In the oilreservoirsof the ZagrosBasin, fractures play a major role in hydrocarbon migration and production. Borehole image log is a powerful tool to study and identify fractures around the wells. These logs provide critical information about orientation, depth and type of natural fractures. Since thereis ...
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In the oilreservoirsof the ZagrosBasin, fractures play a major role in hydrocarbon migration and production. Borehole image log is a powerful tool to study and identify fractures around the wells. These logs provide critical information about orientation, depth and type of natural fractures. Since thereis noaccuratealgorithmfor automaticidentification of fracture parametersonimage logs of the carbonatereservoirsin Iran, interpretation of theselogsisoftendone manually. This process may become erroneous if the interpreter is not sufficiently experienced. Aimed at automatic detecting of fractures in image logs, this paper presents a new implemented method, which is based upon image processingandoptimization techniques,as well as Artificial Bee Colony Algorithm. According to this approach, points related to fractures arefirst extracted from images using classification methods. Then, the Artificial Bee Colony Algorithmis used to determine the number, depth, dip and dip directionof fractureson extracted points. The proposed method is performed on FMS image log ofonewell located in an oilfield in southernIran. Results areshownindensity log, rose diagramandstereogramfor the identified fractures, and the obtained resultsshow efficiency of the proposedmethod.
M. Alimohammadi; P. Behnia; A. Khakazad; M.A. Ghorbani
Abstract
Hired gold-bearing area is located to the northeast of the Lut zone and in the vicinity of the Sistan suture zone. Several post Eocene plutons have intruded into the Eocene volcanic and pyroclastic units and caused hydrothermal alteration and mineralization of gold, copper, lead and zinc. We have applied ...
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Hired gold-bearing area is located to the northeast of the Lut zone and in the vicinity of the Sistan suture zone. Several post Eocene plutons have intruded into the Eocene volcanic and pyroclastic units and caused hydrothermal alteration and mineralization of gold, copper, lead and zinc. We have applied the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data including three visible and near infrared (VNIR), six shortwave infrared (SWIR) and five thermal infrared (TIR) bands to determine the alteration minerals of Hired gold-bearing area. Spectral analysis of the surface reflectance SWIR manifests absorption in 2.20μm and 2.33μm wavelength regions.Absorption at 2.20μm(band6),due to Al-OH anionic agent is consistent with the presence of clay minerals (illite, kaolinite) and sericite, whereas absorption at 2.33μm (band 8) due to Mg-OH anionic agent and carbonates is consistent with the occurrence of chlorite, epidote and calcite minerals. In this study different image processing techniques such as band combination, band ratios transformation, and Binary Encoding were used to identify and delineate the altered minerals accompanied by gold mineralization. The Binary Encoding method was found to be the best image processing technique for delineation of the hydrothermally formed minerals. Analysis of the spectral emission data in the five TIR bands has provided valuable lithological information. It would not be possible to identify silicified rocks in the nine VNIR+SWIR bands due to the lack of recognizable spectral absorption features in quartz at this wavelength region. We have therefore mapped Quartz-bearing surface deposits as well as hydrothermally silicified rocks in the TIR region by using a band ratio (b11×b11) / (b10×b12) image. The results obtained from ASTER data are compatible with conclusions inferred from petrographic and XRD studies of the surface samples. The ASTER data appear to be useful in mapping hydrothermal alteration and in ore deposit exploration.
