جستجوی مقالات مرتبط با کلیدواژه « پتروگرافی آلی » در نشریات گروه « زمین شناسی »

In this study, the organic facies and depositional environments of the Pabdeh Formation are investigated in the Rag-e-Sefid Oilfield located in the southern Dezful Embayment. Little information exists about the organic facies properties of this source rock in the Zagros basin. In the present study, a total of 4 cutting samples were collected from well No. 99 of the Rag-e-Sefid Oilfield. These samples are characterized by a combination of Rock-Eval pyrolysis and organic petrographic techniques. Based on the diagrams of Tmax versus HI, the studied samples contain type II/III kerogen with thermal maturity corresponding to the early stages of the oil generation window. Organic petrographic results are consistent with the presence of a highly organic-rich zone in the middle parts of the Pabdeh Formation, while the upper and lower parts are poor in organic matter. The organic-rich part of the Pabdeh Formation contains abundant amorphous organic matter, bituminite, and framboidal pyrite typical of anoxic depositional environment. The organic-poor sections on the other hand contain negligible organic matter with euhedral secondary pyrite in a light-colored matrix, which suggests oxic depositional condition. These observations suggest that different parts of the Pabdeh Formation were deposited under different environmental conditions. Only the middle part of the Pabdeh Formation has considerable potential for hydrocarbon generation.

In this study the hydrocarbon generation potential and depositional environments of the Pabdeh Formation in the Siah-Makan Oilfield is investigated. For this purpose, a total of 21 cutting samples were collected from well#4 of the studied oil field from the Pabdeh Formation and were analyzed by Rock-Eval 6 pyrolysis method to evaluate the hydrocarbon potential. The HI versus Tmax diagram indicates type II/III kerogen for the studied formation with thermal maturity corresponding to the early stages of the oil generation window. Microscopic observations of selected samples indicates that samples with higher TOC readings contain fossil chambers filled with bituminite. In addition, these samples are characterized by a light-colored carbonate matrix which was deposited under oxic conditions. These observations suggest that the Pabdeh Formation has negligible hydrocarbon potential in the Siah-Makan Oilfield and was deposited under oxic conditions. A Combination of Rock-Eval pyrolysis and organic petrographic methods can be useful for accurate geochemical evaluation of the Pabdeh Formation in future studies.

In this research, the organic matter present in the Pabdeh Formation is investigated using Rock-Eval pyrolysis and organic petrographic techniques. For this purpose, a total of 22 cutting samples were collected at 50-meter intervals from 3 wells in the Kilur-Karim Oilfield. According to hydrogen index (HI) versus maximum temperature (Tmax) diagrams, the Pabdeh Formation in this oilfield contains type II/III kerogen, with thermal maturity corresponding to the early stages of hydrocarbon generation. In general, according to the Rock-Eval pyrolysis data, the middle parts of the Pabdeh Formation show a higher potential for hydrocarbon generation. On the other hand, organic petrography results show that samples from the middle parts of the Pabdeh Formation contain high amounts of amorphous organic matter along with solid bitumen. In addition, the upper and lower parts of this formation contain lower amounts of organic matter and mainly have abundant fossil content. A combination of results from two analytical techniques reveals that the Pabdeh Formation in the Kilur-Karim Oilfield contains a relatively organic-rich zone in the middle, which is surrounded by organic-poor facies above and below. These results can be helpful for a better understanding of the organic facies and palaeodepositional environments of the Pabdeh Formation in the study area.

In this study, the hydrocarbon potential and depositional environments of the Laffan Formation in the Binak Oilfield is investigated. Rock-Eval pyrolysis results indicate that the Laffan Formation contains a mixed type II/III kerogen. Based on the classification of the source rock in terms of total organic carbon (TOC) content, the Laffan Formation can be classified as a good to very good source rock. According to the plots of S1+S2 versus TOC, the Laffan Formation has weak to excellent hydrocarbon potential in the Binak Oilfield. However, organic petrographic inspections showed that the main components of the organic matter are inertinite, bituminite along subordinate amounts of amorphous organic matter. The predominance of Inertinites together with minor Liptinites confirms the type II and IV kerogen mixture in the studied formation. It is noteworthy that the presence of bituminite has a noticeable impact on the results of Rock-Eval pyrolysis. Therefore, in this study, the organic geochemistry of the Laffan Formation was evaluated using organic petrographic results. Accordingly, it is concluded that the organic matter in the Laffan Formation consists mainly of inertinite and bituminite with minor amounts of Liptinites. Therefore, significant hydrocarbon generation potential cannot be expected from this formation in the Binak Oilfield. Considering the public shape of the chromatograms obtained from PY-GC analysis, which show that the initial depositional environment of the Laffan Formation was predominantly oxic marine. The results of this study can be useful for better understanding the Cretaceous hydrocarbon system in the study area.

In order to evaluate the hydrocarbon potential of Garau Formation in Aligudarz section, organic petrography analysis and Rock Eval pyrolysis were performed on samples. In this research totally, 15 samples were studied by transmitted, reflected and fluorescence light and also 12 samples using Rock-Eval pyrolysis device. The existence of bituminite was detected in the transmitted light of amorphous organic matter group and their equivalent in reflected light. Also, the fluorescence of all samples was low, which indicates presence of type II kerogen in the Garau Formation. Since the paleo depositional environment of Garau Formation was pelagic (deep marine) with no terrestrial organic matter input so was no chances of existence of vitrinite macerals for reflectance analysis. Hence, in order to evaluate the thermal maturity, the parameter of thermal alteration index (TAI) and solid bitumen reflection (BRo%) were used, which indicate the early to middle stage of thermal maturity (oil window) of samples in the Garau Formation. According to the parameters obtained from Rock Eval pyrolysis and related diagrams, the quantity of organic matter in samples ranged from good to very good and in terms of quality, show type II and II / III kerogen. Finally, the calculated source potential index (SPI) in the studied section is 19.38 m ton / m2 which shows a high source potential index.

Asmari Formation, comprises mixed carbonate-siliciclastic lithologies in the central Dezful Embayment, with thick shale intervals at the base. In this study mineralogy, organic petrography, thermal maturity and generation potential of the basal shale sediments of the Asmari Formation is investigated in Ahwaz, Marun and Kupal oilfields. Clay mineralogy including kaolinite and mixed layer illite-smectite are the most abundant minerals. Secondary important minerals are calcite and quartz. Microscopic examinations indicate that the organic matter in this unit have mostly originated from continental settings and comprises vitrinite, inertinite, pollen, woody phytoclasts with minor marine liptinite macerals and amorphous materials. TOC contents range from 0.2 to 1.25 wt.% (avg. 0.75 wt%), indicating poor to fair oil generation potential. HI values ranging between 141 to 244 (mg HC/g TOC), is consistent with type III and II/III kerogen. The dominance of terrestrial organic matter (kerogen type III), with relatively high oxygen index indicates that the organic matter was most likely deposited under oxic/suboxic conditions when the relative sea level was low. Vitrinite reflectance (0.45-0.7 %Ro) and Tmax values (417-444 ℃, avg. 432 ℃) suggest that the Asmari basal shale is thermally immature to early mature in the study area.