Multivariate statistical analysis for monitoring the hydrocarbon potentiality of the source rocks in the North Western Desert,Egypt

The authors aimed to examine a multivariate statistical analysis approach for monitoring the hydrocarbon potentiality of source rocks in the North Western Desert to recognize the potentiality of source rocks and subsequently investigate the maturation level of the proven potential source formations for oil preservation. To achieve this aim, they applied multivariate statistics analysis (principle component analysis [PCA], cluster analysis, and correlation coefficient) and Rock-Eval pyrolysis analyses. The results showed that both PCA and cluster analyses have showed two types of source rocks. The first is classified as poor to fair source rock and immature to marginally mature source rock, the second is considered as fair to good source rock and mature to post mature source rock. PCA extracted two independent factors, which explained 81.87% of the total variance. The first type of source rock was responsible for 50% of the total variance and was best represented by variables TOC, S2, OI, and R_o, and the second one was responsible for 31.65% of the total variance and was represented by the HI variable. Pearson correlation coefficient showed a significant positive correlation between TOC and S2 or R_o. A positive correlation between S2 and HI or OI and also between OI and R_o was observed, while no significant correlation was noticed between HI and R_o.     

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.     

Geochemistry,generation and maturation of the hydrocarbons at Wadi Al-Rayan oil field,Western Desert of Egypt

`The present work aims to study the organic chemistry, the generation and maturation of the hydrocarbons encountered at Abu Roash Formation, Wadi El Rayan oil field. The analysis of source rocks indicates the presence of two organic facies. The first is characterized by high total organic carbon of 0.93–3.39%, strongly oil-prone (Type II), and good potential for oil generation (pyrolysis S2 yields 4.54–23.26 mg HC/g rock and HI 488–705 mg HC/g TOC). The second attains good range of organic carbon from 0.90% to 1.57%, which is a mixed oil and gas (Type II–Type III) of fair hydrocarbon generation (pyrolysis S2 yield of 1.98–5.33 mg HC/g). The kerogen type consists of unstructured lipids and some terrestrial material. Plot of Pr/n-C17 versus Ph/n-C18 indicates that the crude oil was derived from mixed source rock, while the maturity profile assigns oil windows (0.6 R_o%) matching topmost of Abu Roash G Member.     

Petroleum source rocks characterization and hydrocarbon generation of the Upper Jurassic succession in Jabal Ayban field,Sabatayn Basin,Yemen

The Upper Jurassic samples of Jabal Ayban field, Sabatayn Basin, western Yemen were used to determine the source rock characteristics and petroleum generative potentials. Based on organic geochemical analysis, the Upper Jurassic source rocks have variable TOC content in the range of 0.82–13?wt%, indicating a fair to very good source rock generative potential. The bulk geochemical results showed that Safer Member contains Type III kerogen grading to mixed Type II–III, while the Lam and Meem members displaying generally Type II, mixed Type II–III and Type III kerogens, which have the ability to generate mixed oil and gas accumulations under thermal maturation level. Vitrinite reflectance in the range (0.35–0.78% Ro) and Tmax in the range (411–445?°C), generally proving that the Meem source rocks have sufficient thermal maturity for hydrocarbon-generation, whereas the Lam and Safer are immature source rocks. 1D basin modelling was performed to analyse the hydrocarbon generation and expulsion history of the study area. Calibration of the model with measured VR (% Ro) and (BHT) data shows that the paleo-heat-flow was high at Late Jurassic. The burial/thermal history models indicate that the source rocks in the Lam and Safer members are immature source rocks and the peak oil generation has not been reached yet. The models also indicate that the early hydrocarbon generation (0.64% Ro) in the Meem source rock occurred during late Jurassic at 150?Ma and the main hydrocarbon generation (0.79% Ro) has been reached approximately at 146?Ma. Therefore, the Meem Member can be consider as generative potentials of prospective source rock horizons in Jabal Ayban field, Sabatayn Basin.     

ORGANIC GEOCHEMISTRY OF POTENTIAL SOURCE ROCKS IN THE TERTIARY DINGQINGHU FORMATION,NIMA BASIN,CENTRAL TIBET

The Tertiary Nima Basin in central Tibet covers an area of some 3000 km² and is closely similar to the nearby Lunpola Basin from which commercial volumes of oil have been produced. In this paper, we report on the source rock potential of the Oligocene Dingqinghu Formation from measured outcrop sections on the southern and northern margins of the Nima Basin. In the south of the Nima Basin, potential source rocks in the Dingqinghu Formation comprise dark‐coloured marls with total organic carbon (TOC) contents of up to 4.3 wt % and Hydrogen Index values (HI) up to 849 mg HC/g TOC. The organic matter is mainly composed of amorphous sapropelinite corresponding to Type I kerogen. Rock‐Eval T_max (430–451°C) and vitrinite reflectance (R_r) (average R_r= 0.50%) show that the organic matter is marginally mature. The potential yield (up to 36.95 mg HC/g rock) and a plot of S2 versus TOC suggest that the marls have moderate to good source rock potential. They are interpreted to have been deposited in a stratified palaeolake with occasionally anoxic and hypersaline conditions, and the source of the organic matter was dominated by algae as indicated by biomarker analyses. Potential source rocks from the north of the basin comprise dark shales and marls with a TOC content averaging 9.7 wt % and HI values up to 389 mg HC/g TOC. Organic matter consists mainly of amorphous sapropelinite and vitrinite with minor sporinite, corresponding to Type II‐III kerogen. This is consistent with the kerogen type suggested by cross‐plots of HI versus T_max and H/C versus O/C. The T_max and R_r results indicate that the samples are immature to marginally mature. These source rocks, interpreted to have been deposited under oxic conditions with a dominant input of terrigenous organic matter, have moderate petroleum potential. The Dingqinghu Formation in the Nima Basin therefore has some promise in terms of future exploration potential.     

Organic geochemistry of the Upper Triassic–Middle Jurassic Shemshak Group (Alborz Mountains,NE Iran)

Abstract

The organic geochemistry of shale samples of Shemshak Group at Dehmolla section in Eastern Alborz Mountains in the present study are discussed throughout the Rock-Eval pyrolysis. The results used to describe the quantity, type, maturity, and petroleum potentials of the Shemshak Group sediments. The pyrolysis data show that the total organic carbon values of the shale samples are between 0.08 and 20.98?wt% and the generation potential (S1+ S2) of the studied samples ranges from 0.02 to 9.47?mg HC/g rock revealing the organic richness of these samples varies from poor to good. The type of hydrocarbon products (S2/S3) ranging from 0.06 to 2.33 and the type of hydrocarbon determined from Tmax versus HI indicate mainly well for gas generation. Based on the HI versus OI plot diagram, the type III of kerogen is the main type of organic matter in studied samples. These data also show that most of the samples were deposited in oxic environments with low sedimentation rate and high amount of organic matter from the terrestrial source. “Tmax” values ranging from 416?°C to 602?°C in studied samples indicate that most of the samples are over mature and located in gas zone.     

COMPOSITION AND PETROLEUM POTENTIAL OF LAKE FACIES IN THE FA-MS-48-73 WELL, MAE SOON STRUCTURE, FANG OILFIELD, NORTHERN THAILAND

The Fang Basin is one of a series of Cenozoic rift‐related structures in northern Thailand. The Fang oilfield includes a number of structures including the Mae Soon anticline on which well FA‐MS‐48‐73 was drilled, encountering oil‐filled sandstone reservoirs at several levels. Cuttings samples were collected from the well between depths of 532 and 1146 m and were analysed for their content of total organic carbon (TOC, wt%), total carbon (TC, wt%) and total sulphur (TS, wt%); the petroleum generation potential was determined by Rock‐Eval pyrolysis. Organic petrography was performed in order to determine qualitatively the organic composition of selected samples, and the thermal maturity of the rocks was established by vitrinite reflectance (VR) measurements in oil immersion. The TOC content ranges from 0.75 to 2.22 wt% with an average of 1.43 wt%. The TS content is variable with values ranging from 0.12 to 0.63 wt%. Rock‐Eval derived S₁ and S₂ yields range from 0.01–0.20 mg HC/g rock and 1.41–9.51 mg HC/g rock, respectively. The HI values range from 140 to 428 mg HC/g TOC, but the majority of the samples have HI values >200 mg HC/g TOC and about one‐third of the samples have HI values above 300 mg HC/g TOC. The drilled section thus possesses a fair to good potential for mixed oil/gas and oil generation. On an HI/T_max diagram, the organic matter is classified as Type II and III kerogen. The organic matter consists mainly of telalginite (Botryococcus‐type), lamalginite, fluorescing amorphous organic matter (AOM) and liptodetrinite which combined with various TS‐plots suggest deposition in a freshwater lacustrine environment with mild oxidising conditions. T_max values range from 419 to 436°C, averaging 429°C, and VR values range from ～0.38 to 0.66% R₀, indicating that the drilled source rocks are thermally immature with respect to petroleum generation. The encountered oils were thus generated by more deeply buried source rocks.     

塔里木盆地东南坳陷中侏罗统杨叶组湖相烃源岩

在塔里木盆地东南坳陷江尕勒萨依发现了中侏罗统杨叶组好烃源岩。该湖相烃源岩以泥岩为主,厚度大约288 m,有机质丰度较高,有机碳含量一般大于2.0%,生烃潜力一般在2 mg/g以上,有机质类型为Ⅱ-Ⅲ型,热压模拟实验产烃率可达300 mg/g以上,处于低成熟—成熟热演化阶段。证实瓦石峡凹陷中南部杨叶组湖相烃源岩发育,成烃条件好,具有较好的勘探前景。     

Organic geochemistry of Gadvan and Kazhdumi formations (Cretaceous) in South Pars field,Persian Gulf,Iran

In Southern Iran, Gadvan (Barremian-early Aptian) and Kazhdumi (Albian) formations are the most effective source rocks and have produced the majority of hydrocarbons reserved in the Zagros Basin especially in Dezful Embayment and Persian Gulf area. In this article, hydrocarbon potential of Gadvan and Kazhdumi formations is investigated in the South Pars field which is southern extension of the North field of Qatar Country. This field is located in Persian Gulf waters and is actually the northern extension of Qatar Arc Paleohigh where geological history of Gadvan and Kazhdumi formations is different from nearby area regarding depositional setting, burial history and source rock maturity.In this study, Gadvan and Kazhdumi formations as source rock candidates, which underlay Upper Dariyan and Mauddud members, respectively, were sampled in two drilled wells of the South Pars field for routine geochemical analysis to investigate hydrocarbon potential of these formations and source rock identification of trapped oil in the Upper Dariyan and Mauddud members. Several samples from top to the bottom of the formations were taken and analyzed by Rock-Eval pyrolysis. The average TOC content of Gadvan and Kazhdumi formations is 0.79 wt. % and 0.49 wt. %, respectively. Rock-Eval results (e.g. HI vs. Tmax) represent that TOC content of these formations contains type II-III kerogens which haven't suffered sufficient thermal maturity (Ro < 0.5%) in this study area. Moreover calculated S2/S3 ratio implies that these formations in central part of Qatar Arc, South Pars field couldn't produce noticeable liquid hydrocarbon.As it is believed, Gadvan and Kazhdumi formations to be source of trapped oil in the system, therefore, in the South Pars field reserved hydrocarbon in Upper Dariyan (Aptian) and Mauddud (late Albian) members which overlie Gadvan and Kazhdumi formations, respectively, are probably generated from Gadvan and Kazhdumi formations of the nearby through and flanks of the Qatar Arc where the burial depth and temperature increase then generated hydrocarbons in downdip area are migrated to the upper carbonate reservoirs in the crest part of the Qatar Arc. Long path migration of the hydrocarbon and source rock with lower organic matter are caused hydrocarbon accumulation in the South Pars Oil Layer (Al-Shaheen) which is approved by professional petrophysical and geological studies of the field.     

优质烃源岩成烃生物与生烃能力动态评价

在海相优质烃源岩常规有机地球化学分析的基础上,综合利用仿真地层热压模拟实验与超显微有机岩石学等新技术对优质烃源岩不同成烃生物生烃潜力进行分析。结果表明:我国下古生界高过成熟海相优质烃源岩目前能够识别的成烃生物主要由底栖生物(或底栖藻类)及菌类(真菌类和细菌)组成,干酪根类型主要为Ⅱ型,这些海相优质烃源岩的原始生烃能力相当于Ⅱ型干酪根,其中底栖藻类相当于Ⅱ1型,真菌细菌类一般相当于Ⅱ2型;其次为浮游生物,生烃潜力与Ⅰ型干酪根相当。优质烃源岩中浮游藻类和底栖藻类在不同成熟阶段的生油能力不同,在高成熟—过成熟阶段生气潜力及其与原油裂解生烃的相对贡献也有差异。因此,下古生界高成熟度烃源岩需要根据不同类型的成烃生物或干酪根类型在各成熟阶段的生油、生气能力进行动态地评价。不同成烃生物生烃潜力研究不仅对常规油气勘探而且对非常规油气勘探也具有重要的借鉴意义。     

烃源岩有机碳含量与生排油效率动态评价

选择海相典型烃源岩样品和人工配制烃源岩样品进行热压模拟实验,对比分析了海相烃源岩的生油量、生排油效率与烃源岩有机碳含量的关系,模拟结果表明:（1）烃源岩的生排油量与烃源岩有机碳含量呈线性正相关关系,生排油效率与有机碳含量呈曲线（非线性）正相关关系,相关系数的大小与烃源岩的干酪根类型、岩性及演化史等有关;（2）在整个生烃演化过程中,高有机质含量的优质烃源岩（TOC一般大于2%）的生排油量和效率都高于中等有机质丰度的中等烃源岩（TOC一般在0.5%~2.0%之间）和低有机质丰度的差烃源岩（TOC一般小于0.5%）,只有高有机质丰度的优质烃源岩才能够大量生排出油并形成大油田,差烃源岩即使很厚也难以形成大量的油气聚集;（3）在地质演化过程中,烃源岩TOC含量及其生排油气能力始终都是动态变化的,因此需要在确定演化阶段的基础上,结合有机碳含量和生排油效率进行烃源岩和资源量动态评价。      

海相优质烃源层评价与形成条件研究

在对全球范围内不同类型海相烃源岩对比分析的基础上,通过筛选出百余块不同类型烃源岩和含油储集岩的热压加水生排油气模拟实验,结合大中型油气田形成的地质条件,对我国海相优质烃源岩的形成条件进行了综合研究,认为海相优质烃源岩主要形成条件有:1)台内盆地及近滨潟湖、台地斜坡、前缘斜坡及前礁等沉积相带,浮游生物发育,水体稳定且较深,处于还原-强还原环境;2)较高的有机质含量,总有机碳含量TOC≥2%;3)Ⅰ-Ⅱ型干酪根,低成熟阶段形成的大量稠油可以沿富有机质页理面以油相网状传递式连续不断地长距离运移,很容易形成大油田;4)烃源转化过程中古油藏及分散在烃源岩和储集岩中的可溶有机质也是优质再生气源,高成熟-过成熟储集岩中的TOC>0.20%时就属优质气源岩,由其原始"油"生成的总生气量与TOC>2%且为Ⅰ-Ⅱ₁型干酪根的烃源岩生成的总生气量基本相当.      

Hydrocarbon potentiality and thermal maturity of the Cretaceous rocks in Al Baraka oil field,KomOmbo basin,south Egypt

This paper aims to evaluate the hydrocarbon potentiality and thermal maturity of the Cretaceous source rocks in Al Baraka oil field in KomOmbo basin, south Egypt. To achieve this aim, geochemical analyses (TOC), Rock eval pyrolysis and vitrinite reflectance measurements (R0) were carried out on the studied rocks. The analytical results of the samples that were collected from five exploratory oil wells revealed that almost Lower Cretaceous formations (Sabaya, Abu Ballas, Six Hills and KomOmbo C, B, A) and Upper Cretaceous formations (Dakhla, Duwi, Quseir, Taref and Maghrabi) are ranged from fair to excellent source rocks for hydrocarbon generation. Oil and gas are mainly the future products of the thermally transformed organic matters within almost samples of the Cretaceous formations, where the Lower and Upper Cretaceous formations contain mixed type II/III and III kerogen besides type II kerogen in KomOmbo (B) and Dakhla formations. The thermal maturity parameters clarified that the Lower Cretaceous formations are belonged to marginally mature (in Sabaya and Abu Ballas formations), whereas the rocks of KomOmbo (B) Formation are mature source rocks and fall in the stage of oil generation and reach to the late stage of oil generation (R0?=?1.25). On the contrary the Upper Cretaceous formations are ranged from immature to marginally mature source rocks and reach only the early stage of oil generation in Maghrabi Formation. This study indicated that there is still a good chance to find oil generated from the Dakhla, Duwi, Maghrabi, Sabaya and Abu Ballas formations if buried in greater depths as well as, KomOmbo B and A intervals which are source rock potentials.     

渤海湾盆地渤中凹陷西南部深层烃源岩有机相预测

针对渤海湾盆地渤中凹陷西南部烃源岩层系多、非均质性较强等特点,开展了烃源岩干酪根显微组分、元素分析、岩石热解、气相色谱等地球化学分析测试,在沉积相的约束下对比了ΔlogR系列方法、多元回归法、BP神经网络法预测有机质丰度参数的优劣,优选BP神经网络法进行烃源岩总有机碳含量、裂解烃含量的单井预测,进而计算得到氢指数预测曲线,结合总有机碳含量进行有机相分析,定量刻画各层系烃源岩的有机相,分析烃源岩的优劣和展布特征。结果表明,BP神经网络法的预测精度相对较高,东营组二段下亚段烃源岩主要为Ⅱ₂型干酪根,氢指数为125～400 mg/g,总有机碳含量基本小于3%,其有机相主要为BC相、C相和CD相;东营组三段烃源岩主要为Ⅱ₁—Ⅱ₂型干酪根,沙河街组沙一二段、沙三段烃源岩主要为Ⅰ—Ⅱ₁型干酪根,这三套烃源岩的氢指数为250～650 mg/g,总有机碳含量为3%左右或大于3%,其有机相主要为B相、BC相和C相。沙河街组优质烃源岩主要发育于研究区中南部,是下一步勘探的重点区域。      

松辽盆地长岭断陷层烃源岩地球化学特征研究

下白垩统沙河子组沉积的暗色泥岩和煤层是松辽盆地长岭断陷层主要的烃源岩,火石岭组和营城组为次要烃源岩。钻井和露头样品表明,火石岭组烃源岩有机碳含量0.50%~8.55%、生烃潜量2~17mg/g、氯仿沥青"A"含量0.04%~0.33%,干酪根类型以Ⅱ型为主,成熟度演化处于生气的过成熟阶段;沙河子组烃源岩有机碳含量1.00%~6.54%、生烃潜量2~8mg/g、氯仿沥青"A"含量0.2%~0.5%,干酪根类型以Ⅰ型和Ⅱ型为主,成熟度演化处于高成熟—过成熟阶段;营城组烃源岩有机碳含量0.5%~2.5%、生烃潜量0.5~4.0mg/g、氯仿沥青"A"含量0.05%~0.20%,干酪根类型以Ⅱ型为主,处于成熟—高成熟阶段。综合评价沙河子组为中等—好烃源岩,而营城组和火石岭组烃源岩属中等烃源岩。      

川西北地区海相烃源岩地球化学特征、分布规律及天然气勘探潜力

川西北地区为近年来四川盆地天然气勘探的热点地区,但时至今日对该区海相烃源岩的地球化学特征和分布仍缺乏全面的研究.选取8条露头剖面对川西北地区下震旦统陡山沱组、上震旦统灯三段、下寒武统筇竹寺组、下志留统龙马溪组、中泥盆统、中二叠统茅口组、上二叠统龙潭组/吴家坪组和大隆组8套海相烃源岩进行了系统的有机地球化学分析,探讨了该...     

鄂尔多斯盆地东缘康宁地区煤系烃源岩评价

本文应用氢指数(IH)和最高热解温度(Tmax)综合确定康宁地区本溪组-太原组-山西组泥岩干酪根类型绝大多数是Ⅱ2、Ⅲ型干酪根,即有机质类型以混合型-腐殖型为主,偏生气型。康宁地区本溪组泥岩有机质丰度在0.11%~9.1%范围内,平均为2.99%;太原组泥岩有机质丰度在0.26%~12%范围内,平均为3.81%;山西组泥岩有机质丰度在0.14%~9.97%范围内,平均为2.28%。康宁地区山西组煤的镜质组反射率变化于0.93%~1.21%之间;本溪组煤的镜质组反射率为1.06%~4%,多在1.06%~1.2%之间。研究区煤系烃源岩有机质的背景成熟度处于成熟阶段中-后期,已有大量烃类生成。     

黏土矿物对不同类型烃源岩热解参数影响

选取高岭石、伊利石和绿泥石3种黏土矿物,以不同比例分别与Ⅰ型、Ⅱ型和Ⅲ型干酪根混合并进行热解实验,探讨黏土矿物种类及含量对不同类型烃源岩热解参数影响.实验结果表明,黏土矿物对干酪根热解生烃作用同时具有层间吸附作用和表面吸附作用,黏土矿物的表面吸附作用会增大矿物的催化能力,层间吸附会造成大分子烃类被吸附在层间沉淀,抑制热...     

柴达木盆地北缘井下石炭系烃源岩的发现及其地质意义

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