Evaluation of the nature,origin and potentiality of the subsurface Middle Jurassic and Lower Cretaceous source rocks in Melleiha G-1x well,North Western Desert,Egypt

The present work aims to evaluate the nature and origin of the source rock potentiality of subsurface Middle Jurassic and Lower Cretaceous source rocks in Melleiha G-1x well. This target was achieved throughout the evaluation of total organic carbon, rock Eval pyrolysis and vitrinite reflectance for fifteen cutting samples and three extract samples collected from Khatatba, Alam El Bueib and Kharita formations in the studied well. The result revealed that the main hydrocarbon of source rocks, for the Middle Jurassic (Khatatba Fm.) is mainly mature, and has good capability of producing oil and minor gas. Lower Cretaceous source rocks (Alam El Bueib Fm.) are mature, derived from mixed organic sources and have fair to good capability to generate gas and oil. Kharita Formation of immature source rocks originated from terrestrial origin and has poor to fair potential to produce gas. This indicates that Khatatba and Alam El Bueib formations take the direction of increasing maturity far away from the direction of biodegradation and can be considered as effective source potential in the Melleiha G-1x well.     

Evaluation of possible source rocks and extracts characteristics from Safir-1x well,North Western Desert,Egypt

The pyrolysis and vitrinite reflectance estimations for fifteen shale rock tests and additionally, geochemical burial history, and gas chromatography – mass spectrometry parameters were talked about to explore the hydrocarbon generation and maturation level and time, type of hydrocarbon produced of rock units of Safir-1x well. The results assign that the Bahariya Formation is poor to great source rock to create oil and gas, with a lower thermal maturation degree than the Khatatba and Alam El Bueib formation. Alam El Bueib is viewed as good to excellent source rock for oil and gas age, having marginally high level of thermal maturation at oil window at around 40 million years. Khatatba formation achieved the oil and gas generation window at about 80 and 50 million years separately and considered excellent source rock.

The molecular gas chromatography and mass spectrometry parameters demonstrated that the extracts of source rocks reflected that the Bahariya and Alam El Bueib extracts have a mixed sources formed under transitional conditions at low grad of thermal maturation. Khatatba source rock extracts originated from marine sources formed under reducing conditions at high grade of maturation.     

Evaluation of organic matters,hydrocarbon potential and thermal maturity of source rocks based on geochemical and statistical methods: Case study of source rocks in Ras Gharib oilfield,central Gulf of Suez,Egypt

In this study, we apply geochemical and statistical analyses for evaluating source rocks in Ras Gharib oilfield. The geochemical analysis includes pyrolysis data as total organic carbon (TOC%), generating source potential (S2), production index (PI), oxygen and hydrogen indices (OI, HI) and (Tmax). The results show that the Cretaceous source rocks are poor to good source rocks with kerogen of type III and have the capability of generating gas while, the Miocene source rocks are good to excellent source rocks with kerogen of type III–II and type II and have the capability of generating oil and gas. The analyzed data were treated statistically to find some factors, clusters, and relations concerning the evaluation of source rocks. These factors can be classified into organic richness and type of organic matter, hydrocarbon potentiality and thermal maturity. In addition, cluster analysis separated the source rocks in the study area into two major groups. (1) Source rocks characterized by HI >300 (mg/g), TOC from 0.76 to 11.63 wt%, S1 from 0.44 to 9.49 (mg/g) and S2 from 2.59 to 79.61 (mg/g) indicating good to excellent source rocks with kerogen of type III–II and type II and are capable of generating oil and gas. (2) Source rocks characterized by HI <300 (mg/g), TOC from 0.31 to 2.07 wt%, S1 from 0.17 to 1.29 (mg/g) and S2 from 0.31 to 3.34 (mg/g) indicating poor to good source rocks with kerogen of type III and are capable of generating gas. Moreover, Pearson’s correlation coefficient shows a strong positive correlation between TOC and S1, S2 and HI and no correlation between TOC and Tmax, highly negative correlation between TOC and OI and no correlation between Tmax and HI.     

Oil:Oil Correlation for Some Oil Fields in the North Western Part of the Western Desert,Egypt

Abstract

Physical and specific geochemical analyses are used in detail for the petroleum geochemical studies to permit the correlation of six crude oil samples from Western Desert Egypt. Different analytical techniques, including liquid chromatographic separation, gas chromatography, and gas chromatography-mass spectrometry (GC-MS), were used to characterize the oil samples. The oils were identified using oil characterization parameters including specific gravity (°API), sulfur content, distribution of n-alkanes, carbon preference index (CPI), pristane/phytane ratio, isoprenoid/n-alkane ratios, and detailed biological marker analysis. All these parameters showed that the studied oil samples are correlated with each other, where they are similar in their oil type maturation and source depositional environments.     

Oil:Oil Correlation for Some Oil Fields in the North Western Part of the Western Desert, Egypt

Physical and specific geochemical analyses are used in detail for the petroleum geochemical studies to permit the correlation of six crude oil samples from Western Desert Egypt. Different analytical techniques, including liquid chromatographic separation, gas chromatography, and gas chromatography-mass spectrometry (GC-MS), were used to characterize the oil samples. The oils were identified using oil characterization parameters including specific gravity (°API), sulfur content, distribution of n-alkanes, carbon preference index (CPI), pristane/phytane ratio, isoprenoid/n-alkane ratios, and detailed biological marker analysis. All these parameters showed that the studied oil samples are correlated with each other, where they are similar in their oil type maturation and source depositional environments.     

Source rock evaluation of some upper and lower Cretaceous sequences,West Beni Suef Concession,Western Desert,Egypt

West Beni Suef Concession is located at the western part of Beni Suef Basin which is a relatively under-explored basin and lies about 150 km south of Cairo. The major goal of this study is to evaluate the source rock by using different techniques as Rock-Eval pyrolysis, Vitrinite reflectance (%Ro), and well log data of some Cretaceous sequences including Abu Roash (E, F and G members), Kharita and Betty formations. The BasinMod 1D program is used in this study to construct the burial history and calculate the levels of thermal maturity of the Fayoum-1X well based on calibration of measured %Ro and T_max against calculated %Ro model. The calculated Total Organic Carbon (TOC) content from well log data compared with the measured TOC from the Rock-Eval pyrolysis in Fayoum-1X well is shown to match against the shale source rock but gives high values against the limestone source rock. For that, a new model is derived from well log data to calculate accurately the TOC content against the limestone source rock in the study area. The organic matter existing in Abu Roash (F member) is fair to excellent and capable of generating a significant amount of hydrocarbons (oil prone) produced from (mixed type I/II) kerogen. The generation potential of kerogen in Abu Roash (E and G members) and Betty formations is ranging from poor to fair, and generating hydrocarbons of oil and gas prone (mixed type II/III) kerogen. Eventually, kerogen (type III) of Kharita Formation has poor to very good generation potential and mainly produces gas. Thermal maturation of the measured %Ro, calculated %Ro model, T_max and Production index (PI) indicates that Abu Roash (F member) exciting in the onset of oil generation, whereas Abu Roash (E and G members), Kharita and Betty formations entered the peak of oil generation.     

埃及西沙漠盆地中生界烃源岩特征及剩余资源分布

西沙漠盆地是埃及三大主要含油气区之一,已发现大量的油气田,现处勘探发现中期,预探风险增大。为此,在详细评价盆地烃源岩地球化学特征基础上,运用盆地数值模拟技术定量分析剩余资源潜力。研究认为,中侏罗统Khatatba组Safa段和Zahra段煤系暗色泥页岩以及上白垩统Abu Roash组AR-F段暗色泥页岩是盆地的3套主力烃源岩,各凹陷烃源岩广泛分布,厚度变化较大。Khatatba组烃源岩TOC含量在0.5%~10%,裂解烃S₂含量高,为中等-很好烃源岩;Abu Roash组AR-F段烃源岩TOC主要在0.5%~3%,裂解烃S₂含量中-高,属中等-好烃源岩。这3套烃源岩有机质干酪根类型以混合Ⅱ型为主,其次是Ⅲ型,少量为Ⅰ型。指出Khatatba组2套烃源岩全盆处于热演化成熟大量生排烃阶段,凹陷中心达高熟生烃、局部过熟生气阶段,油气并生;Abu Roash组AR-F段烃源岩仅Abu Gharadig和Natrun凹陷进入成熟生烃阶段。提出盆地北部地区主要由侏罗系Khatatba组烃源岩供给油气,东南部地区则有侏罗系Khatatba组和白垩系AR-F段双源供烃。计算表明,盆地剩余可采资源量达6.51×10⁸ t,剩余资源潜力很好;其中,南部Abu Gharadig凹陷古生界、侏罗系和下白垩统AEB,北部Matruh凹陷古生界、Faghur凹陷上白垩统,油气探明程度低,剩余资源可观,为下步勘探的有利方向。     

Burial and thermal history simulation of the subsurface Paleozoic source rocks in Faghur basin,north Western Desert,Egypt: Implication for hydrocarbon generation and expulsion history

Paleozoic Zeitoun, Desouqy and Dhiffah formations represent source rocks to hydrocarbon in Faghur basin, north Western Desert, Egypt. They are characterized by a sufficient amount of organic matter belonging to kerogen type III and mixed type II/III, which are in maturation stage. A 1D-basin modeling was performed by using geological and geochemical data of the Paleozoic source rocks from five wells in Faghur basin, north Western Desert, Egypt. These data used in 1D basin modeling for constructing and understanding of burial and thermal geo-histories of Faghur basin and for simulating and predicting the timing of petroleum and expulsion for the Paleozoic source rocks in the studied wells. Burial and thermal history models indicate that the Zeitoun Formation entered onset of oil generation in the studied wells during Late Cretaceous (100.10–91.65 my) with transformation ratio (TR) 10–25, peak oil during Late Cretaceous (91.65–79.30 my) with TR 25–50 and late oil stage at Late Cretaceous (79.30 my-0) to present day with TR 50–60.45. Desouqy Formation entered onset of oil generation also during Late Cretaceous (94.43–73.60 my) with TR 10–25 in the studied wells, peak oil during Late cretaceous (73.60–62.40 my) with TR 25–50 and Late oil stage during Late Cretaceous to present day (62.40 my-0) with TR 50–61.82. Dhiffah Formation entered onset of oil generation in the studied wells during Early to Late Cretaceous (102.11–92.27 my) with TR 10–25, peak oil during Late Cretaceous (92.27–86.40 my) with TR 25–50 and late oil stage at Late Cretaceous to present day (86.40 my-0) with TR 50–67.27. No cracking oil to gas in the studied Paleozoic source rocks in the studied wells. These basin modeling results also suggest that the Paleozoic source rocks act as an effective source rock where a significant amount of petroleum is expected to be generated and expelled to any nearby prospect reservoir rocks in the Faghur basin.     

Bulk Geochemical Characteristics of Crude Oils From Wells in the North Western Desert,Egypt

Abstract

Different oil samples were collected from oil fields in the North Western Desert; namely, Meleiha, Razaak, and North Qarun fields. These oils were analyzed geochemically, including sulfur content, American Petroleum Institute (API) gravity, and gas chromatography The results showed that API gravity and sulfur content indicate that the crude oils have high mature level of marine origin. Distribution of n-alkanes (Carbon Preference Index [CPI], pr/ph, and isoprenoide/n-alkanes ratios) reflects that the oil samples originated mainly from marine organic sources deposited in a reducing environment. This indicates that the oil samples under investigation are well correlated with each other in the western part of the North Western Desert.     

Isopach,lithofacies changes,and source rocks chracteristics of Khatatba and Alam El Bueib formations of some wells in North East Western Desert,Egypt

The present work deals with isopach, lithofacies changes, and source rock chracteristics of Khatatba and Alam El Bueib formations of some wells in North East Western Desert. Isopach and lithofacies changes showed that the thickness of Khatatba Formation increases toward the south western direction and decreases toward northern parts, and the sediments consisting of sandstone and shale facies indicate a shallow marine environment. Alam El-Bueib sediments increase toward the north direction, and argillaceous sandstone facies reflect terrestrial-to-shallow marine environment. The geochemical analysis showed that Khatatba Formation bears a mature source rock and has poor-to-good generating capability for both oil and gas and lie within the early generation window and oil window. Alam El Buieb Formation constitutes a mature source rock and has poor-to-good generating capability for both oil and gas. It can be stated that Khatatba and Alam El Buieb are the main source rock for hydrocarbon accumulations rich with organic sediments and could be considered as effective source rocks for generating hydrocarbons in the the studied wells.     

Sedimentary facies analysis of the Upper Bahariya sandstone reservoir in East Bahariya C area,North Western Desert,Egypt

The present work aims to deduce the depositional processes of the Lower Cenomanian Bahariya Formation, that is one of the main hydrocarbon siliciclastic reservoirs in the Northern Western Desert of Egypt. This has been achieved through the analyses of the core photographs, micro-resistivity image logs, mud logs and conventional wireline logs. The Bahariya Formation comprises a complex of depositional lithofacies such as interbedded siltstone, shale, sandstones and pebbly sandstones. The current work highlights the effectiveness of the integrative approach. A variety of datasets including core photographs, micro-resistivity image logs, mud logs and conventional wireline logs are integrated to define the conceptual depositional model in the study area.Different recorded sedimentary features point to various depositional processes. Hummocky cross stratification (HCS) is the common sedimentary structure indicating the storm action. Wave ripples are recorded providing evidence for fair-weather action on shoreface. Rhythmic heterolithics, tidalites indicate the tidal processes. The upper part of the Bahariya Formation has been influenced by wave and storm processes more than the lower parts. The core and image facies are designated, being dominated by Sandstone (S), Siltstone (Z), Mudstone (M), Heterolithic (H) and Limestone (L.s). The studied core and image facies with wireline logs facies are grouped into five major facies associations (FA). They are Tidal Channel and Tidal Creeks, Tidal Flat, Storm, Shoreface, Offshore Transition to Offshore Facies Associations. The integrative approach indicates that the Upper Bahariya Member has been deposited in a storm influenced tidal coastal realm.     

Source rock evaluation of Kharita and Bahariya formations in some wells,North Western Desert,Egypt: Visual palynofacies and organic geochemical approaches

Palynofacies analyses were applied on ninety-one samples from the subsurface Albian – Cenomanian succession represented by Kharita and Bahariya formations, encountered in El-Noor, and South Sallum wells, located in the North Western Desert, Egypt, to visually characterize the content of dispersed organic matter, as well as, organic geochemical characterization to reveal the depositional paleoenvironments and source rock potentiality. The result recognized of five palynofacies associations in the studied interval. The deposition of Kharita Formation took place mainly in a steady and a relatively stable deltaic to marginal environment continued as well in the lower part of Bahariya Formation with minor changes. The marine influence became more common in the upper part of Bahariya Formation showing the exceptional high hydrocarbon potential recorded in the studied interval. This indicates marine transgression by the end of the early Cenomanian (Upper Bahariya) age. Samples from the Kharita Formation contain abundant brown phytoclasts which suggest gas-prone kerogen type III and IV. While Bahariya Formation includes translucent, brown cuticles and woody tracheid phytoclasts pointing to more promising gas-prone kerogen type III. The organic geochemical analysis shows poor to fair gas-prone source rock potential within the study section., Thermally, the color of the spore grains in Kharita and Bahariya formations show that dark yellow to orange, indicates immature besides their general little poor hydrocarbon generation potentiality.     

Mineralogical,geochemical and hydrocarbon potential of subsurface Cretaceous shales,Northern Western Desert,Egypt

Twenty four Cretaceous shale core samples of Gibb Afia-1, Betty-1, Salam-1X and Mersa Matruh-1 wells were mineralogically and geochemically studied using XRD, XRF and Rock Eval Pyrolysis. Kaolinite, smectite and illite are the main clay minerals in addition to rare chlorite, while the non-clay minerals include quartz, calcite, dolomite and rare siderite. The shales were derived through intensive chemical weathering of mafic basement and older sedimentary rocks. These sediments were deposited in a near-shore shallow marine environment with some terrestrial material input. The shales have poor to fair organic content. It is marginally to rarely mature.     

Characterization of the Organic Matter for Some Crude Oils from the North Western Part of the Western Desert, Egypt

A direct method for crude oil evaluation based on spectral techniques is demonstrated. This direct method is demonstrated for five crude oils from the north western part of the western desert, Egypt. FTIR spectroscopy was used to study the distribution of functional groups contained in the crude oil samples. Some ratios calculated from peak heights of selected infrared bands allow for a better comparison of the spectra. These ratios will be useful to give valuable informations about the origin and thermal maturation of the organic matters. ¹³C NMR spectroscopy could provide a measure of the relative proportions of crude oils aliphatic and aromatic carbons so that the technique is proving to be a valuable organic matter maturation and typing tool. The proportion of organic carbon present in aliphatic structures correlates with oil-generating potential of a source rock. These spectroscopic techniques have been used to study the entire structures of crude oil samples. They may provide valuable informations about the aromaticity and diverse functionalities which are important to find out about the thermal history of the crude oil samples.     

北黄海盆地中生界烃源岩评价

北黄海盆地位于黄海海域北部,为中新生代盆地,勘探程度较低,尚处于早期评价阶段。通过对盆地东部钻井烃源岩有机质丰度、有机质类型和有机质成熟度等有机地化参数分析,认为:上侏罗统烃源岩是具一定潜力的中等烃源岩,也是目前发现原油的油源岩和有效烃源岩;下白垩统烃源岩是本区目前最好的烃源岩,但成熟度偏低,应作为具有一定潜力的潜在油源岩或有效烃源岩加以重视。此次研究对该地区烃源岩的认识起了重要的补充和促进作用,对油气勘探也具有很好的指导意义。     

烃源岩热模拟实验中重排藿烷类化合物变化特征及其意义

为了探索热演化程度对烃源岩中重排藿烷类化合物形成的影响及其地球化学意义,通过对渤海湾盆地PL-1井未成熟烃源岩样品进行热模拟实验研究,分析重排藿烷类化合物组成随热模拟实验温度变化特征以及重排藿烷参数与热演化程度的关系。在烃源岩的不同热演化阶段,重排藿烷类化合物变化特征不同。烃源岩热模拟实验250℃时的重排藿烷绝对浓度相对于烃源岩原样中的重排藿烷绝对浓度略有升高;250~400℃时的重排藿烷绝对浓度均逐渐降低。在热模拟实验中重排藿烷绝对浓度降低比例呈现出高成熟阶段>成熟阶段>低成熟阶段的规律;在300~400℃对应的成熟—高成熟阶段,化合物绝对浓度降低幅度呈现出17α（H）-藿烷 >18α（H）-新藿烷 >17α（H）-重排藿烷的特征。17α（H）-重排藿烷参数在低成熟—成熟阶段基本不变,在成熟—高成熟阶段逐渐增大。未成熟—低成熟阶段是重排藿烷类化合物形成的主要阶段,较高的热演化程度对重排藿烷的形成具有一定影响,重排藿烷参数可以作为烃源岩成熟—高成熟阶段有效的成熟度指标。     

Characterization of the Organic Matter for Some Crude Oils from the North Western Part of the Western Desert,Egypt

Abstract

A direct method for crude oil evaluation based on spectral techniques is demonstrated. This direct method is demonstrated for five crude oils from the north western part of the western desert, Egypt. FTIR spectroscopy was used to study the distribution of functional groups contained in the crude oil samples. Some ratios calculated from peak heights of selected infrared bands allow for a better comparison of the spectra. These ratios will be useful to give valuable informations about the origin and thermal maturation of the organic matters. ¹³C NMR spectroscopy could provide a measure of the relative proportions of crude oils aliphatic and aromatic carbons so that the technique is proving to be a valuable organic matter maturation and typing tool. The proportion of organic carbon present in aliphatic structures correlates with oil-generating potential of a source rock. These spectroscopic techniques have been used to study the entire structures of crude oil samples. They may provide valuable informations about the aromaticity and diverse functionalities which are important to find out about the thermal history of the crude oil samples.     

Hydrocarbon potentiality, burial history and thermal evolution for some source rocks in October oil field, northern Gulf of Suez, Egypt

This paper attempts to apply a one dimensional model on four source rocks (Belayim, Lower Rudeis, Thebes, and Brown Limestone formations), in East Warda concession, October oil field, throughout the different geological times. Moreover, the fundamental aspects of the petroleum system in the study area is evaluated through studying maturation and hydrocarbon potential in order to gain an understanding of onset of oil generation and expulsion. The position of three wells (syn. or pseudo wells) is proposed based on the available geological and thermal data. Also, the existing temperature database is enhanced by using the available temperature data for 220 wells in the Gulf of Suez and the Red Sea, 53 wells in the Mediterranean Sea, 29 wells in the Nile delta, 7 wells in Sinai, 2 wells in Upper Egypt and 39 wells in the Western desert. Finally, the timing of oil generation for Belayim, Thebes, Lower Rudeis and Brown Limestone source rocks in the Northern Gulf of Suez area is updated. From this study we conclude that, the cumulative yield of the Belayim and Lower Rudeis formations is lower than that of the Thebes and Brown Limestone formations.     

Characterization and correlation of crude oils from some wells in the North Western Desert,Egypt

Characterization and correlation of crude oils from some wells in the North Western Desert, based on six crude oil samples, were studied by different analytical techniques, including API gravity, sulfur content, nickel and vanadium, bulk compositions and saturated fraction obtained from gas chromatography have been studied. The results show that the crude oils are normal to medium aromatic oils, with high API gravity and high sulfur content. V, Ni, V/Ni and V/(V + Ni) reflecting oils might be sourced from non-clastic source rocks, possibly carbonates, deposited under anoxic-suboxic conditions. Bulk compositions revealing that the crude oils were derived from marine organic sources. While, the paraffins and naphthenes percent indicates that the oils belong to paraffinic to naphthenic oil types, deposited in slightly anoxic to suboxic conditions and contained marine organic matter. Thermal maturity data showed that the oil samples were generated from mature source rocks. This indicates the studied oil samples are well correlated with each other, where they are similar in their oil type maturation and source depositional environments.     

Hydrocarbon source-rock potential of the Jurassic succession in eastern part of the North Western Desert,Egypt

The hydrocarbon potential is determined by the quantity and quality of organic matter encountered in the Jurassic sediments in two wells at the Northern Western Desert. It utilizes to define the zones of oil and gas using the well logging data for calculates the total organic carbon (TOC). The evaluation of source rock has been based on two steps; the first one depended on the geochemical parameters including TOC, S1, S2, Tmax, and Vitrinite reflectance (Ro %) of two wells JG-1 and JD-4. The second step was to calculate (TOC) from wireline logs. The well log types utilized in such kind of analysis are the density log, sonic log, resistivity log and gamma-ray log. The stratigraphic sequence, in the studied wells ranges in age from Paleozoic to Recent. The present work focuses on the Jurassic rocks represented by Khatatba Formation as they include the main source horizon. Based on the obtained results, Jurassic sediments called as fair to excellent source rock potential. The genetic type of organic matter can be identified through the study of pyrolysis data, which indicate that is rich in mixed oil and gas-prone kerogen except few samples reflect type I organic facies.