جستجوی مقالات مرتبط با کلیدواژه "marun oil field" در نشریات گروه "زمین شناسی"

In the present study, calcareous nannofossil of the Gurpi Formation have been studied from well No. 123 of Marun oil field in the Zagros sedimentary basin. In this study, thirty-eight nannoplankton species belonging to eighteen genera were introduced from the Gurpi Formation deposits. Based on index calcareous nannofossil species, the Gurpi Formaation deposit was subdivided into nine calcareous nannofossil biozones, including CC17- CC25 zones (Sissingh, 1977) and UC12-UC20 (Burnett, 1998). The identified biozones are assigned to the Late Santonian-Late Maastrichtian ages for the studied interval. In order to paleoecology and Paleoenvironment studies, the diversity, abundance, size and extent of preservation of nannofossil taxa were also investigated. The distribution and abundance of some species such as Micula decussata, Micula murus and Watznaueria barnesiae indicate that the temperature and environmental stress have increased towards the end of the Formation. Also, the sedimentary environment of Gurpi Formation during the Late Cretaceous was mainly in low to mid-latitudes based on calcareous nannofossil assemblages.

This study was aimed at the biostratigraphy and sedimentary environments reconstruction in one of the wells in Maroun oilfield at Dezful embayment zone. We also compared the studied sub-surface section with the equal intervals in Mala-Kuh, Ghale-Nar oilfield, Moshkan section, and Firouzabad section. The thickness of Asmari Formation in the studied well is 370.5 m and consists mainly of limestone, dolomite, dolomitic limestone, sandstone and argillaceous limestone. In this well, the lower boundary of the Asmari Formation with Pabdeh Formation and its upper boundary with Gachsaran Formation is continuous.

For this study, 150 thin sections (mainly drilled cores) were studied in detail for paleontology, biostratigraphy, allochems identification, and microfacies determination. References such as Loeblich and Tappan (1980), Boudagher-Fadel, (2008), Adams & Bourgeois (1967), and other related articles were used to identify the available microfossils. We used the biozonation scheme of Laursen et al. (2009) and Van Buchem et al. (2010) to define and correlate the biozones. Classification of rock types was done according to Dunham (1962) and Embry & Klovan (1971), and microfacies identification and interpretation were carried out based on Wilson (1975), Buxton & Pedley (1989), Geel (2000), and Flugel (2010),

Based on paleontological studies, 43 genera and 61 species of benthic and planktonic foraminifera were identified. They have been classified into six zones (five assemblage zones and one indeterminate zone) as follows:1- Globigerina spp.-Turborotalia cerroazulensis-Hantkenina Assemblage ZoneThis biozone is 76 meters thick and lies between the depths of 3706.5 to 3630.5 m. It corresponds to the upper part of the Pabdeh Formation. In this biozone with Oligocene (Rupelian) age, Globigerina spp. are abundant, and the extinction of Turborotalia cerroazulensis occurs in this biozone.2- Lepidocyclina-Operculina-Ditrupa Assemblage ZoneThis biozone is 129.5 meters thick and lies between 3630.5 to 3501 m. The beginning of this biozone is based on the first occurrence of the Lepidocyclina sp. and Operculina complanata. Its end is marked by the first appearance of the Miogypsinoides compalanatus and Spiroclypeous blankenhorni. This biozone belongs to the Chattian-Rupellian age.3- Archaias asmaricus-Archaias hensoni-Miogypsinoides compalanatus Assemblage ZoneThe thickness of this biozone is 80 meters and lies between 3501 to 3421 meters deep. The onset of this biozone is marked by the first occurrence of Miogypsinoides compalanatus and Spiroclypeous blankenhorni. The first occurrence of Elphidium sp.14, Peneroplis farsensis and disappearance of Archaias distinguish the end of the biozone. The age of this biozone is Chattian.4- Elphidium sp.14 – Peneroplis farsensis Assemblage ZoneThis Assemblage zone is 83 meters thick and lies between 3421 to 3338 meters deep. The age of this biozone is Aquitanian. The onset of this biozone is determined by the occurrence of the Elphidium sp.14, Peneroplis farsensis, and the end of this biozone is characterized by a decrease in the fossil fauna assemblage known as the Ambiguous Zone.5-Indeterminate ZoneWith 70.44 meters thickness, this zone lies between the depths of 3338 to 3267.57 meters. A decrease in fossil assemblages characterizes this interval. According to its stratigraphic locality, this indeterminate zone is related to Aquitanian (Laursen et al., 2009). The fossils present in this biozone are very sparse and consist mainly of porcelaneous and indeterminate milliolids.6- Borelis melo curdica-Borelis melo melo Assemblage Zone?This biozone is related to the uppermost part of the Asmari Formation. The beginning of this biozone is defined based on the occurrence of the Borelis spp., continues to the end of the Asmari Formation. This biozone is 7.56 meters thick and lies between 3267.56 to 3260 meters deep. The age of this biozone is cautiously Burdigalian.Based on the mentioned biozones, the age of Asmari Formation in the studied well is Rupelian – Chattian –?Burdigalian.According to sedimentary texture, sedimentary structures, skeletal and non-skeletal elements in the microscopic studies if the provided thin section, 12 microfacies related to the outer ramp, middle ramp (distal and proximal parts), shoal and inner ramp environments (patch reef, lagoon (semi-restricted and restricted( and tidal flat were identified in the studied well. Gradual changes of facies to each other, the lack of coated structures, and the absence of coated grains are the main evidence suggesting deposition in a homoclinic carbonate ramp. Microfacies analysis shows that planktonic foraminifera in the upper part of the Pabdeh Formation belongs to the outer ramp. Due to the presence of large hyaline foraminifera, the lower part of the Asmari Formation is deposited in the distal part of the middle ramp, while the presence of lenticular foraminifera demonstrates the proximal ramp environment. A high-energy, shallow-shoal environment with the presence of thick-walled lenticular foraminifera, cementation, and grainstone textures characterize the boundary between the middle and the inner ramp. Inner ramp environment is considered by the presence of patchy corals (patch reef) and imperforate foraminifera (Archaias, Peneroplis, milliolids) of the lagoon (semi-restricted and restricted lagoon) and tidal flat zones.

In the oil buildings to investigate fractures in the reservoir rock fractures in stages of production and field development is very important and necessary. Now application of software repository in the realization of this issue will help to petroleum with the geologists.. Marun oil field is one of the largest oil fields in the South West Iran of the city of Ahvaz in the Northeast and the North embayment Dezful of geology in the eastern. Marun field is the most important Asmari reservoir. The aim of this study was to investigate systematically Asmari reservoir fractures and the development of fractures in the reservoir. For this purpose, using image logs, best and most complete method interpretation and results of 11 wells in fracture studying and 16 wells in in-situ stress direction studying. According to frequency of fractures (based on image logs interpretation results) in the southern and north-eastern limb of the field, The theory of tectonic folding and bending events later caused the possible activities during the north-south strike-slip faults affect the compression force has been created to strengthen. Most of image logs data in Marun field are fractures with extensions; N155E, N130E, N95E, N60E, N30E.

Marun oilfield is located in the middle part of Dezful Embayment and is situated along the Aghajari، Ahvaz and Ramin anticline. Given the important role of fracture characteristics for improving production، so the aim of this research is to investigate the density pattern of fracture in Asmari formation in Marun oilfield. For this purpose، results of image log، core data، graphic well log، methods of inscribed circle analysis and curvature changes geometry of anticline were analyzed. Asmari formation is the main reservoir rock in Marun oilfield that divided into five zones. Limestone and dolomite are the main lithology of zones 1، 2 and 3 which has a high density of fractures (especially in zones with 90% dolomite). Also there is less fracture density (micro fracture) in the 4 and 5 Asmari zone due to an increase of shale and marl layers and due to less break ablity has a less distribution of fractures. The result show that there are a good conformity existed between the results of inscribed circle analysis، image log، core data، curvature and the presence of fractures in Marun anticline. The data indicate that highest density of fracture density concentrates in the southern limb in the central region of anticline and also in the north limb in the northeast region of the anticline. So، finally using these parameters، it is recommended that further development and production wells be drilled in the north eastern part of the oil filed as well as center part of southern flank of the anticline.

Marun Oil Field is located in the southern part of Dezful embayment, in the mid part of the zagros simple folded mountain range and along the Ramin and Aghajari anticlines. In this study, based on the subsurface data and using subsurface analytical methods the folding mechanism and fractures of this anticline has been studied. In this research, using the primary results of geophysical data, analysis methods, geometric curvature changes, mud loss and reservoir engineering data, geometry of anticline and fractures associated with folding have been analyzed. Folding mechanisms in this anticline is a combination of flexural-sliding folding and folding with neutral surface. In other words, the Marun subsurface anticline is a thrust fault- related fold and also a faulted detachment fold. Seismic profiles showthat the Marun anticline as a concentric fold that from surface to depth space has been decreased. This decrease of space associated with faulting in the southern flank and these faults disappear in the Gachsaran formation. A good conformity among geometric analytical methods, mud loss data, index productivity on bending region in the Marun anticline and presence of fractures in this region exist. The data analysis shows that the highest density of fractures is related to the bending region in the Marun Oil Field. Finally, using these parameters, it is recommended that for further drilling of development and production wells these parameters must be regarded and the northeastern part of the Oil Field as well as southern flank of the anticline must be given full consideration.