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

The most important reason for studying any oil reservoir is the more efficient use of the production parts of the reservoir and the first step in identifying the reservoir is its zoning. Zoning is determined based on lithological changes by combining production data and petrophysical logs in each reservoir. In order to improve and accelerate the zoning of oil reservoirs, like other branches of science, the use of software has become common in recent years. One of the most powerful of these software's is Cyclolog. The science of using this software is cyclostratigraphy, which can be used to separate reservoir zones based on sedimentary cycles and their knowledge. Cyclolog software with the help of petrophysical logs taken from the wellbore and especially gamma diagram (GR) allows subsurface matching and preparation of matching charts in selected wells. In this study, in the three oil fields studied (Karanj, Paranj and Parsi) using cyclolog software, a total of seven positive timelines (Pb3000, Pb2000, Pb1500, Pb1000, Pb500, Pb400, and Pb300) as well as five negative timelines (Nb4000, Nb3000, Nb2000, Nb1000, and Nb500) were detected. Accordingly, the Pb1500 timeline is the separator and the boundary of the Chattian and Aquitanian peaks, which in the wells of all three studied fields almost cross the boundary of reservoir zones 3 and 4. The Nb4000, Nb3000, and Nb2000 timelines are also Chattian age. The Nb3000 timeline in Karanj oil field has crossed the boundaries of zones 4 and 5 in most of the wells due to calibration with biometric evidence (biostratigraphy) and indicates the top of the formation. The age of the Nb500 timeline is Burdigalian and passes through the middle of their reservoir zone 1 in the study area. The boundary between the Aquitanian and Burdigalian peaks is defined by the Nb1000 timeline. This timeline crosses the boundaries of zones 1 and 2 in all three fields studied.

In this research based on the petrographic analysis 12 microfacies belonging to outer ramp, middle ramp, shoal and inner ramp were introduced, which led to recognition of some paleoeological parameters. In the studied well, the Asmari Formation sediments have been deposited from normal to hypersaline, oligophotic to euphotic and oligotrophic to eutrophic conditions. Deep parts of the basin with low hydrodynamic energy, soft and stable substrate contain foraminifera with thin and elongate tests; the shallow parts of the middle ramp (proximal) and shoal with high hydrodynamic energy, hard and unstable substrate including thick-wall,  lenticular hyaline benthic foraminifera and porcelaneous forams with thick walls are distributed in the lagoon facies belt. The high abundance of the large benthic foraminifera, coralinacea red algae and coral fragments indicate warm and tropical to subtropical environments during the deposition of the Asmari Formation. High proportion of the epifaunal to infaunal benthic foraminifera in the studied well suggest an oxygenated marine environment. In adition in this research 4 carbonate associations including Nanofer, Rhodalgal, Foralgal and Foramo were recognized. Finally, 4 positive- and 5 negative- boundary surfaces (PB and NB, respectively) were introduced; some of which are well correlated with stage boundaries.

The Asmari Formation in the Marun oilfield is composed of fossiliferous limestone, dolomitic limestone, argillaceous limestone, sandstone and shale. It is the major reservoir rock of Iran in several oil fields of the Zagros Basin. The age of Asmari Formation in this oilfield is Oligo-Miocene (Rupelian–Burdigalian). In this study, subsurface correlation between the four wells in the Marun oilfield, based on climate stratigraphy is done by using Cyclolog Software. Nine Positive and ten negative bounding surfaces have been identified. Some positive and negative bounding surfaces coincide with sequence boundaries and maximum flooding surface, respectively. In addition, some of the positive bounding surfaces identified the main time boundary (stage boundaries). Reservoir correlation between the ten compartments reservoir zones of the Asmari Formation in the Marun oilfield is done with these boundary surfaces. Some reservoir zones (especially the lower and middle Asmari reservoir zones) show perfect matching but others do not show the boundary of adaptive zones. It seems combining these data with other factors such as lithology, porosity and permeability, detail revision of reservoir zoning of Asmari Formation in Marun Oilfield is required.