الفهرس | Only 14 pages are availabe for public view |
Abstract The Abu Qir area lies in the northwestern side of the Nile Delta region, the offshore Mediterranean Sea, between longitudes 30° 00´- 30° 24´E and latitudes 31° 18´- 31° 40´N. The Nile Delta is one of the most promising provinces in Egypt due to its significant hydrocarbon potential. The Abu Qir basin is considered as one of three main sub-basins in the Nile Delta that has been formed due to the effect of the Serravalian tectonic movement during the Late Miocene. Patterns of sedimentation in the northern delta between the late Oligocene and the Pliocene were controlled by four reactivated faults named the Bardawil line, Qattara-Eratosthenes line, Pelusium line, and Hinge zone. The sedimentary sequence penetrated by wells in the study area consists of thick Miocene-Pleistocene siliciclastics. The lithostratigraphy of the study area is represented by Miocene sediments (Qantara, Sidi Salem, and Abu Madi formations) and the Pliocene–Pleistocene sequences (Kafr El Sheikh, El Wastani, and Mit Ghamr formations), which are represented mainly by shale or clay with sandstone interbeds. Also, Qantara Formation (Early Miocene) is composed of calcareous marine shales and sandstones. In addition, the formation is overlain unconformably by the Sidi Salem 125 Summary and Conclusions Formation (Middle Miocene) which is dominated by shales with some sandstones facies, deposited under marine to fluvial condition. Moreover, it is unconformably overlain by Qawasim and/or Abu Madi formations. Moreover, these formations are overlain unconformably by Kafr El Sheikh Formation, which is composed of shales and sandstones. In addition, the thickness of the Kafr El Sheikh Formation increases towards offshore areas. Furthermore, Kafr El Sheikh Formation is overlain by El Wastani Formation (claystones and sandstones), which represent a transitional facies between the shelf facies of the Kafr El Sheikh Formation and the fluvio-deltaic facies of the overlying Mit Ghamr Formation. The purpose of this study is to evaluate the possible source rocks in Abu Qir fields, through several geochemical analyses and predicting the maturation levels reached by the source rocks and the time of hydrocarbon generation. Additional objectives are to characterize the condensates recovered from Kafr El Sheikh and Abu Madi reservoirs from the same fields using biomarker analyses, and to identify the origin of the natural gas in this area on the basis of geochemical and stable isotope data. The geochemical analyses (total organic carbon analyses, Rock Eval pyrolysis and vitrinite reflectance measurements) of one hundred and sixty- 126 Summary and Conclusions two (162) cuttings samples of the Kafr El Sheikh, Sidi Salim and Qantara formations from North Abu Qir-1 (NAF-1), North Abu Qir-101 (NAF-101), West Abu Qir-1X (WAQ-1X) and West Abu Qir-4X (WAQ-4X) wells in Abu Qir concession suggest the following:- 1- Kafr El Sheikh Formation is immature to marginally mature rocks source rock in the drilled sections, with poor to fair generating potential to generate mainly gas. 2- Sidi Salim Formation has poor generating potential to generate mainly gas in the drilled sections. This formation is marginally mature in NAF-1 and NAF-101 wells and entered the oil window in NAF-1 and WAQ- 1X wells. 3- Qantara Formation is penetrated only in NAF-101 well and is considered to be immature to marginally mature rock with poor generating potential to generate gas. Four condensate samples from the studied wells were analyzed using whole-oil gas chromatography (GC), medium pressure liquid chromatography (MPLC), carbon isotopic analysis, and gas chromatography-mass spectrometry analysis (GC-MS) on the saturate and aromatic fractions. In addition, four gas samples were collected from the previous wells and analyzed for methane (C1), ethane (C2), ethylene (C2H4), propane (C3), 127 Summary and Conclusions propylene (C3H6), butanes (i-C4and n-C4), pentanes (i-C5and n-C5), C6+ and non-hydrocarbons composition and δ13C isotopic analysis of methane, ethane, propane, and CO2. Also, be aware that the gases were recovered from the same reservoirs as the condensates. The geochemical analyses were conducted through Stratochem Laboratories and provided by Abu Qir Petroleum Company. The geochemical characterization of four condensate samples suggest their derivation from clay-rich source rocks with mixed organic sources deposited under oxic to suboxic low salinity conditions, suggesting a transitional environment. The abundance of both C27 and C29steranes indicate both terrestrial and marine influence. However, the presence of moretane and the richness of 6RP indicate a more significant contribution from terrestrial organic matter. In addition, the presence of oleanane (albeit in low concentration) may imply Late Cretaceous-Early Tertiary age for the condensate source rocks. Moreover, the maturity indicator ratios indicated that Abu Qir condensates were generated during the early stage of source rock maturation. Molecular and isotopic composition for the analyzed gases from the AQ Concessions suggests that the studied gases are of thermogenic origin and 128 Summary and Conclusions are dominated by mixed type II/III kerogen. Finally, the different maturity ranges for the studied gases may be attributed to the mixed kerogen Types (II and III) of the studied gases. One-dimensional modelling of burial history and thermal maturity was constructed for the wells NAF-1, NAF-101, WAQ-1 and WAQ-4 and suggested that all the wells show the same geological settings, which is characterized by the presence of three main sedimentation phases (periods) separated by Hiatus or uplift events. The most rapid and main burial phase starts by the end of the Pliocene and continues to present day. Although the study wells have the same geology but the preserved thicknesses show slight differences from well to another. Cumulative Hydrocarbon Curves were constructed for the four investigated source rocks (Kafr El Sheikh, Sidi Salim, Qantara and Tineh formations) suggesting that the Kafr El Sheikh source rocks in the drilled sections are currently immature to marginally mature and only minor hydrocarbon generation could be expected, while no hydrocarbon expulsion have been taken place, however the Sidi Salim source rocks are generated higher amounts relative to that obtained from the Kafr El Sheikh source rocks but also no expelled hydrocarbons had been taken place. In addition, the 129 Summary and Conclusions 130 Qantara source rocks reflect that there is noticeable hydrocarbon generation has occurred. Although the generated hydrocarbons from Qantara Formation appear significant and much greater than those appeared from the shallower source rocks (Kafr El Sheikh and Sidi Salim) but it does not overcome the saturation threshold (20%) of the source rock and therefore no hydrocarbons expulsion could have been take place. The cumulative hydrocarbon curves of the Tineh source rock (Oligocene) suggest that it reaches its capacity for hydrocarbon expulsions in all the studied wells and it is in early or mid of the wet gas/condensate maturity stages. The oil expulsion from Tineh source rock started during the Pleistocene and continued to recent with total expelled oils ranged between 26 bbls/acre-ft to 31 bbls/acre-ft and total expelled gas of about 42-89 ft^3/acre-ft of gases (hypothetical numbers). |