جستجوی مقالات مرتبط با کلیدواژه « فروافتادگی دزفول » در نشریات گروه « زمین شناسی »

Kupal Oil Field is one of the important oil fields in the Zagros Basin, located in the eastern part of the Dezful embayment, adjacent to Aghajari Oil Field and Marun Oil Field. Some characteristics of the fold elements, such as the fold interval angle and axial surface, were determined in the Asmari folded horizon using the interpreted seismic profiles. Based on the deviation of the axial surface from the vertical surface and determination of shear angle and shear strain, minimum and maximum quadratic stretch and strain ratio (R) values were calculated in different parts of the anticline. With application of graphical functions the amounts of fold aspect ratio were determined along the anticline. Base on the results, the amounts of shear strain varies from 0.01 to 0.09 in deferent parts of anticline. Also results show the amounts of strain ratio in range of 1.25 to 1.38 and shortening about 5% to 17% in different parts of the kupal anticline oil field.

The Oligo-Miocene Asmari Formation forms the main reservoir rock of many Dezful Embayment fields. Microfacies analysis, diagenetic features, and sequence stratigraphic evaluation of the Asmari Formation were carried out based on the petrographic investigation, petrophysical logs, and core measurement porosity and permeability data. Petrographic analyses led to the identification of twelve microfacies indicating five subenvironments including tidal flat, lagoon, barrier (belonging to inner ramp), middle ramp, and outer ramp, all of which are representing a homoclinal ramp. Tidal flat, lagoonal, and barrier microfacies are mostly present in the upper parts of the Asmari Formation, while middle and outer ramp microfacies were largely developed in the middle part. Cementation, compaction, dolomitization, dissolution, and fracturing are the main diagenetic processes in this formation. Compaction and cementation have negatively affected reservoir quality while fracturing, dolomitization, and dissolution contributed to reservoir quality enhancement. The sequence stratigraphic studies represent three 3rd order sequences of early Aquitanian, late Aquitanian, and early Burdigalian age based on the main features of microfaces, their depositional environments, and shallowing and deepening-upward trends. Microfacies of the Transgressive System Tract (TST) have been affected by compaction, dissolution (moldic), cementation, and slightly dolomitization in the middle to outer ramp parts. The Highstand System Tract in the inner ramp part has been affected by dolomitization, dissolution, and fracturing close to the sequence boundaries, and has a better reservoir quality than the Transgressive System Tract.

The only outcrop of Asmari formation in the Dezful embayment is visible in the Asmari anticline. In order to estimate the strain parameters and shortening values, 26 geological cross sections were prepared perpendicular to the anticline axis. Based on the, interlimb angle measurements, the interlimb angles of the northern and central parts of the anticline show smaller angles than the southern parts. Determination of strain ratio (R) values indicates the strain values between 1.12 - 1.52. The zoning map of strain ratio values shows higher strain values in the northern and central parts of the anticline. Using geological cross sections and measuring the base length of the folded layer of Asmari formation (L0) and the straight length of the layer (L1), the percentage of shortening values were calculated in each section. The results show the occurrence of 1.8% to 12% shortening in different parts of the anticline. Shortening map of the Asmari anticline shows more shortening amounts in the northern and central parts of the anticline than the southern parts.

In this research, the Asmari Formation in the Mansourabad Oilfield in the southern part of the Dezful Embayment has been studied in order to determine the age, study and identify microfacies and depositional environment. The biostratigraphy study was based on benthic foraminifera and recognition of microfacies and depositional environment carried on the thin sections prepared from core and cutting samples of two wells from the studied oilfield. The lower boundaries of this formation are conformable and gradually with the Pabdeh Formation, but sharp with the Gachsaran Formation, respectively. According to the study, four assemblage zones were identified in the Asmari Formation. Lepidocyclina-Operculina-Ditrupa zone indicates the age of Rupelian/Chattian, Archaias asmaricus-Archaias hensoni-Miogypsinoides complanatus zone indicates the age of Chattian, Indeterminat zone indicates the age of Aquitanian, and Borelis melo curdica-Borelis melo melo zone indicates the age of Burdigalian. Based on petrographic analysis nine microfacies related to tidal flat, lagoon and open marine sub-environment were identified that were deposited on a carbonate ramp environment extended from inner to outer ramp. This study led to better understanding of the stratigraphy and depositional environment of this reservoir formation.

In order to study lithostratigraphy, microfacies, and biostratigraphy of the Pabdeh Formation based on the new biozonation of planktonic foraminifera in the Tethys region, 1 subsurface section in well No. 314 of Gachsaran Oil Field has been studied.The Pabdeh Formation with a thickness of 241m consists mainly of shale, calcareous shales, argillaceous limestones, and cherty limestones. The lower boundary of the Pabdeh Formation with the Gurpi Formation is unconformable and the upper boundary with the Asmari Formation is conformable.Investigation of the stratigraphic distribution of these microfossils in the subsurface section (Gachsaran well No. 314) led to the identification of 52 genera and 21 species of planktonic foraminifera and 17 biozones based on equivalent to new biozone of (Wade et al, 2011) in the global biozonation in this region. These identified biozones include 2 biozones in the Paleocene, 13 biozones in the Eocene, and 2 biozones in the Oligocene in the studied and are well correlated with some biozones in the Tethys region. Based on the foraminiferal assemblages and their biozonation, the age of the Pabdeh Formation in well No. 314 of Gachsaran Oil Field is Middle Paleocene (Selandian) – Early Oligocene (Rupelian). Defined biozones are compared with the other sections presented in the Izeh Zone (Tange Hatti, north flank of Tange Pabdeh, Chahardeh, and Lar Mountains) in the Zagros Basin.Petrography and microscopy studies of the Pabdeh Formation in section imply, these sediments are belonging to microfacies (Deep Shelf) and were deposited part of a carbonate platform.

Dezful Embayment is the most important fertile oil province of the Zagros Fold-Thrust Belt. It includes several incompetent strata as basal and intermediate detachment levels that play a significant role on the structural styles and hydrocarbon preservation. The Oligocene–Miocene deposits of the Asmari Formation are the most important oil reservoir in the Zagros fold–thrust belt in southwest of Iran. The Aquitanian evaporites of Kalhur Member of the Asmari Formation were deposited in north Dezful Embayment. Based on the interpretation of seismic profiles, the influence of the evaporitic Kalhur Member of the Asmari Formation on the geometry of deformation was obvioused in different parts of the north Dezful Embayment. Determining the geometry variations in the different depths reduces the uncertainties of petroleum exploration. Parsi Field is a slightly asymmetric NW-SE trending anticline lying in Khuzestan, at the southwest edge of the Zagros mountain belt in the north central part of the Dezful Embayment. The Asmari reservoir in the Parsi field comprises various combinations of limestone, dolomite and anhydrite. These deposits form a major partin Oligo-Miocene carbonate ramp system. In this research, the effects of the Kalhur detachment horizons on the folding style of the Parsi oil field have been investigated using seismic and subsurface well data

In this study, the Asmari reservoir in 39 wells in one of the oil fields of southwestern Zagros, located in the Dezful region, was investigated using well log tomography of Gamma ray logs and core porosity data. For this purpose, two-dimensional and three-dimensional models of gamma and core porosity logs in 4 reservoir zones of Asmari Formation have been designed by Petrel software. Among the slice of Gama log and porosity data, 2 slice were selected from the upper and lower sections of the zones, and a total of 8 tomographic sections from 10 key wells were prepared and compared with each other. The results of gamma logs and porosity tomography models are very close and compatible with each other and show that there is an inverse relationship between gamma values and porosity in the slices made by Asmari Formation in the studied wells. Also, with increasing dolomitization in the zones, the petrophysical characteristics have changed and the amount of porosity has increased. Based on the well log tomography model of the studied oil field, it was found that zone 2 with the lowest gamma value and the highest dolomite value, has higher porosity than other zones and can be the main target of production wells in the field. Since drilling wells is expensive and time consuming, it is possible to achieve very close and accurate results of well drilling using well log tomography. Therefore, tomography studies can be very useful before increasing excavations in the area for general information.

Cenomanian –Turonian carbonate sequences of the upper Sarvak Formation are among the most important hydrocarbon reservoirs of the Zagros area in SW Iran. Depositional and diagenesis histories were investigated using the petrographic studies of core samples and thin sections of this formation in 6 wells from 5 oilfields located in central and southern parts of the Dezful Embayment. Facies analysis has resulted in the recognition of 14 microfacies that are grouped into six facies associations (basin, outer ramp, middle ramp, open marine lagoon, shoal, and restricted lagoon), according to their facies characteristics and comparison to the standard microfacies models. A homoclinal ramp model was proposed as depositional setting of the Sarvak Formation. Important diagenetic alterations of this formation include dissolution, cementation, dolomitization, de-dolomitization, silicification, neomorphism, compaction, and fracturing. They represent a paragenetic sequence of marine, meteoric (eogenetic and telognetic), and shallow- to deep burial realms. Sequence stratigraphic interpretations resulted in the differentiation of two (third-order?) depositional sequences in the upper Sarvak Formation (mid Cenomanian – early Turonian). Finally, facies characteristics and diagenetic alterations are interpreted in a sequence stratigraphic framework.

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 order to study biostratigraphy and the determination of biozonationes in the Pabdeh Formation based on the new planktonic foraminifera biozonationes in the Thethys region, one subsurface section in well 1 of Parsi Oil Field was selected in the southern Dezful Embayment. Based on this study, biostratigraphic study of 320 thin section from well 1 of Parsi Oil Field has been carried out. The Pabdeh Formation with a thickness of 404 m consists mainly of shale, marl, argilaceous limestone and cherty limestone.The lower boundary of the Pabdeh Formation with the Gurpi Formation is unconformable and the upper boundary with the Asmari Formation is conformable. Biostratigraphic studies led to the recognition of 25 genera and 75 species of planktonic foraminifera and then 19 biozones equivalent to new biozone of Wade et al. (2011) in the Thethys region. These identified biozones include 3 biozones in the Paleocene, 11 biozones in the Eocene and 5 biozones in the Oligocene in the studied section in well 1 of Parsi Oil Field and are well correlated with some biozones in the Tethys region. Based on the identified biozones and fossil contents, the age of the Pabdeh Formation is Middle Paleocene (Selandian) – Late Oligocene (Chattian). Defined biozones are compared with the other sections presented in the Izeh Zone (Tange Hatti, Tange Pabdeh and Chahardeh)

Determining the direction of deformation migration in the fold- thrust belts, is one of the basic aspects for understanding the structural evolution of the fold and thrust belts. By studying the timing and mechanism of deformation and compare it with different regions of a fold thrust belt, it is possible to gain a better understanding the history of the structural evolution. The timing and development of deformation in the Zagros folded belt is one of the widely studied topics and the general belief is that collision of  two plates of central Iran and Arabian began in Miocene, and gradually developed from the northeast to the southwest. According to the present study, the timing of  folding of the Jaril anticline in the northern of Dezful embayment  is estimated to be end of Middle miocene (Serravalian). The results of the present study indicated that the onset folding of the Jarik anticline in this area coincides with the deposition of the lower Aghajari Formation.

The Gaschsaran Formation, is one of the major and important stratigraphic units in Iran, and is regarded as substantial Asmari cap rock thuse, is significant economically. Generally, the Gaschsaran Formation with a thickness of 1200 to 1600 m, is present in South of Dezful embayment. The studied area is located in the Gachsaran oilfield, which consists of the Gachsaran member 1 with a thickness of 40 m. This research is focused on lithological variations, depositional fabrics together with the depositional environment in the well No. x in the Gachsaran oil field. The main sedimentary fabrics, as a result of gypsum to anhydrite transformation, occurred in this formation during diagenetic processes and lath fabrics, as well as flow fabrics, present in this formation. Based on the field investigation along with well logging data, the studied area involved reversed anticline, and variations in units indicate member 4 as anticline core as a result of other strata shortening. Three carbonates, evaporite, and shale facies are recognized based on their allochems, fabrics, texture, and lithology in the studied section. The studied facies represent a carbonate-evaporite platform involving sabkha and salt pan, tidal flat and lagoonal depositional environments during Miocene. Geochemical analysis, X-Ray-EDX, and SEM data revealed freshwater flooding, evaporative concentration, and desiccation stages during evaporite deposition. The Br element variation along the stratigraphic column indicated water entrance and evaporation occurred during evaporite deposition in this formation.

The Geomorphic indices including mountain front sinuosity (Smf), valley floor width to valley height ratio (Vf), basin shape index (Bs), and stream length–gradient index (SL) have been calculated for determination of various tectonic activities along the Aghajari fault. The mountain front sinuosity (Smf) index was calculated about 1.007 to 1.58 respectively in the active and inactive parts of the Aghajari fault. The basin shape (Bs) index has been calculated between 7.83 for the very active parts and, 1.18 for the low active parts of the fault. The amounts of valley floor width to valley height ratio (Vf) index show the range between 0.21 to 5.29 in the active parts with V shape valley morphology and inactive parts with U shape valley morphology respectively. The stream length–gradient (SL) index was calculated between 1414.58 in the high active tectonic and 385.14 in the low active tectonic parts of the study area. With application of the GIS techniques and the overlaying the Smf, Bs, Vf and SL data layers the area was divided into three different tectonic zones and quantitative active tectonic zoning map was prepared for the study area. In this active tectonic map, classes 1 to 3 respectively show the highest to lowest tectonic activity along the Aghajari fault. Results reveal that the Aghajari fault in the central and southeastern parts except for some small areas shows the medium tectonic activity and in the northwestern parts shows the low tectonic activity manner.

To the southwest of Iran there are large reservoirs of oil and gas including Jurassic and Cretaceous carbonates, with good source rocks in the succession of the Early Cretaceous and Jurassic. The purpose of this study was to investigate the production, migration and characterization of Pabdeh, Kazhdumi, Garru and Serglu source rocks in the study area. For this purpose, burial history and one-dimensional thermal modeling in four wells and two-dimensional modeling in one section for the study area were evaluated using Openuploo software to determine the maturity of layers and hydrocarbon outflow. Comparison of measured vitrinite temperature and reflectance values with model results was used for model calibration. The results of one-dimensional modelling of the burial and thermal history in this study show that the Sergloo, Grove and Kazhdumi formations have reached maturity and have had hydrocarbon outflow, but the Pabdeh Formation has not reached sufficient maturity for hydrocarbon maturation and production. The results of migration model in the studied section show that the two Early Cretaceous and Middle Cretaceous hydrocarbon systems were separated by Kazhdumi Formation and therefore hydrocarbon migration in deeper layers of Kazhdumi was mostly lateral to Abadan plain. The hydrocarbon produced from the Kazhdumi Formation, in addition to ornithologically rearing the upper layers, migrated to the Ilam and Sarvak layers due to the general slope of the layers laterally and toward the Abadan plain. In general, the process of maturation of source rocks decreased from east to west of the study area.

The Oligo-Miocene Asmari Formation consists of carbonate facies with lesser amount of evaporites. The evaporite ‎unit deposited at the base of the Asmari Formation is called Basal Anhydrite. Depositional model was investigated ‎using field data, geophysical logs and the Basal Anhydrite facies in the Dezful Embayment (DE). Seven microfacies ‎were recognized in seven outcrops located in the Bangestan, Sefid, Asmari and Anaran anticlines. They were ‎deposited in tidal flat and lagoon environments of inner ramp. Anhydrite facies is a distinct and pure evaporite unit ‎with no carbonate components. Two main textures, fine crystalline (alabastrine) and coarse crystalline ‎‎(porphyroblast), were distinguished in samples indicating replacement of anhydrite by gypsum. Gamma ray, neutron, ‎sonic and density logs of 20 wells in 15 oilfields in the DE indicate that evaporite facies, present at the base of the ‎Asmari Formation, is composed of anhydrite and halite. Anhydrite is present in the most of the DE wells and halite ‎and small amount of anhydrite are present in three central wells. The results of geophysical logs and microfacies ‎studies of the Asmari Formation reveal shallow water-shallow basin environment for the Basal Anhydrite.‎

Mishan Formation is one of the Neogene stratigraphic units that is widely distributed in the south and southwest of Iran. In recent years, in order to achieve the exact age of this formation, studies have been carried out using fossil data and the use of strontium isotopes. In the young folded areas, such as Zagros folded belt that containing sediments that have not been deeply buried, using magnetostratigraphic study is one of the most appropriate methods for obtaining the age of sediments. This method can be used for non-marine sediments such as alluvial deposits that often lack the biostratigraphic and radiometric properties for age determination can also obtain the sedimentation rate of the studied sequence. In the present study, the age of the Mishan Formation was studied using magnetostratigraphic method in Jarik anticline on the northeast of Dezful embayment. In the studied section, the age of the lower and upper boundary of the Mishan Formation, is estimated to be 14.1 and 13.6 million years (middle Miocene) respectively. Also the average sedimentation rate for this formation (after secondary compaction) was obtained 38 cm / 1000 years.

The one of the most important petroleum source rocks in the Zagros basin is the Pabdeh Formation that has been investigated by geochemical techniques. The aim of this study was to assess the quality of organic matter, evaluate thermal evolution and highlight Pabdeh Formation potential as a source rock of Ramin oilfield located in Dezful Embayment. Based on HI versus Tmax and HI versus OI diagrams were used in classifying the organic matter in the formation indicating the presence of Type II kerogen. Most samples of the Pabdeh formation have Tmax values more than 435ºC indicate that the shale of formation is thermally mature with respect to petroleum generation. Hydrogen Index (HI) values range from 150 to 350mgHC/gTOC and S1 S2 yields values ranging from 11.98 to 31.06mgHC/g rock, suggesting that the shale have oil generating potential.The TOC of shale samples of the studied Ramin Well no. 4 ranges from 1.82 to 3.5%, an indication of a very good source rock of terrestrially derived organic matter. So, investigation of the variation S1 S2 and TOC parameters indicated that Pabdeh Formation (in the well) is assessed a good source rocks in producing hydrocarbon. Also with T max examination showed that formation is mature enough to generate hydrocarbon and has yet entered oil generation window.

Introduction: Oil-bearing fluid inclusions within oil reservoirs are usually trapped in the course of migration and during the formation of diagenetic neomorph mineral phases and associated cements. Their size often varies from 2mµ to 50µm (England et al. , 1987). They preserve the physic-chemical data such as temperature and composition of the fluids at the time of entrapment (Roedder, 1986; Barker & Goldstein, 1990; Sisson et al. , 1993). Since the oil reservoirs are commonly filled by oils of many origins with different maturity at various stages, investigation of the oil inclusions can help researchers determine the history of accumulation of oil within the reservoirs (England et al. , 1987). Microthermometric studies have been done in order to determine the maximum burial temperature, paleogeothermal gradient and maximum depth of burial (Burruss, 1987; Lowenstein & Brown, 1998; Ceriani et al. , 2002; Ceriani et al. , 2006; Ceriani et al. , 2011) The main objective of this research is to use the petrographic and fluorescence spectroscopy along with oil and aqueous inclusions microthermometry in cements of Asmari and Bangestan sedimentary formations of the Kupal oil field. For recognition of oil inclusions flourescenc microscopy was applied. The phenomenon of fluresence in organic matter consists of the emission of photons by chemical entities. Flurophores are able to absorb part of the incident energy, rising from a fundmental energy state of higher energy. The return to the ground state may then produce a luminescence phenomenon such as fluorescence (Hercules, 1965; Mousseron et al. , 1969). Essentially the fluorescence of organic molcules is related to the energy tranistion phenomena in the c=c bands. The conjugated system reguires a lower excitation energy therefore, aromatic and polyaromatic compounds are mainly responsible for the flurescence properites of sedimentary organic matters (Wehry, 1967). Oil inclusions are Classified with respect to changes in color of fluorescence: Orange colors with maturity (API): 15-20, Yellow colors with maturity (API): 20-30, blue colors with maturity (API): 30-40, white colors with maturity (API): 40-50 and White with maturity (API) > 50 (Lang & Gelfand, 1985).

Geologic setting: Kupal oil field is one of the main oil fields which is located about 60 km northeast of Ahwaz, Khuzestan Province. The area is located in central part of northern Dezful embayment. This oil field includes Asmari and Bangestan reservoirs both of which are currently producing oil.

Methods: In this study, samples were collected from sedimentary rocks and core logs of the Asmari reservoir (No. 40 and 44) and Sarvak reservoir (No. 20 and 4). To carry out this study, wafers of doubly polished sections (150 -200 µm) were prepared for fluorescence studies and discremination of inclusions (aqueous and petroleum) was done by using Olympus microscope equipped with UV light (with 340 nm filter). The microthermometric measurements were performed using a Linkam THMS600 heating - freezing stage.

Discussion: Fluid inclusions petrograohy: Based on petrographic studies, The majority of the studied fluid inclusions are hosted by sparry calcite cements and calcites filling the solution casts and cavities. The sparry calcite cements exhibit a variety of primary and secondary fluid inclusions. Most of them are hydrocarbon bearing fluid inclusions. Fluid inclusions micro termomerty: The obtained results showed that the highest frequency of homogenization temperatures in oil inclusions are 60-70 ºC and 70-80 ºC in Asmari Formation and 65-85 ºC and 100-120 ºC in Sarvak Formation. Also the salinity of fluid inclusions in the studied samples vary from 5 to 15 wt% NaCl eq. Fluid inclusions fluorescence: The fluorescence studies on oil reservoirs of Asmari and Bangestan (Sarvak) Formations illustrate two types of fluorescent colors, yellow and blue. Combination of the results obtained from micro-thermometry and fluorescence studies indicate that Asmari and Bangestan (Sarvak) reservoirs were fed by two different sources or were filled through several stages of diagenetic processes. The blue fluorescent color indicates the higher degree of maturity (API: 50-40) while yellow fluorescent color reflects relatively immature and heavy (API: 30-20) oil. Aqueous fluids are non-fluorescent.

Conclusion: The sparry calcite cements exhibit a variety of primary and secondary fluid inclusions. Most of them are hydrocarbon bearing fluid inclusions. Highest frequency of homogenization temperatures in oil inclusions are 6070 ºC and 70-80 ºC in Asmari Formation and 65-85 ºC and 100-120 ºC in Sarvak Formation. The results of fluorescence stuies showed that the oils from Asmari and Bangestane (Sarvak) reservoirs have two types of fluorescent colors (yellow and blue) that indicating the reservoirs were fed by two different sources. The blue fluorescent color indicates the higher degree of maturity (API: 50-40) while yellow fluorescent color reflects relatively immature and heavy (API: 30-20) oil. Combination of fluorescent, geochemical, and microthermometric data in Asmari and Bangestan Formations revealed that there were various generations of hydrocarbons filling the reservoirs.

Acknowledgments: The authors would like to thank the National South Oil Company for providing samples and funds for this research project. Our appreciation also extend to University of Tabriz, Research Institute of Petroleum Industries, and Iran Mineral Processing Research Center for furnishing laoratory facililities for this research