Miscibility of light oil and flue gas under thermal action

The miscibility of flue gas and different types of light oils is investigated through slender-tube miscible displacement experiment at high temperature and high pressure.Under the conditions of high temperature and high pressure,the miscible displacement of flue gas and light oil is possible.At the same temperature,there is a linear relationship between oil displacement efficiency and pressure.At the same pressure,the oil displacement efficiency increases gently and then rapidly to more than 90% to achieve miscible displacement with the increase of temperature.The rapid increase of oil displacement efficiency is closely related to the process that the light components of oil transit in phase state due to distillation with the rise of temperature.Moreover,at the same pressure,the lighter the oil,the lower the minimum miscibility temperature between flue gas and oil,which allows easier miscibility and ultimately better performance of thermal miscible flooding by air injection.The miscibility between flue gas and light oil at high temperature and high pressure is more typically characterized by phase transition at high temperature in supercritical state,and it is different from the contact extraction miscibility of CO_(2) under conventional high pressure conditions.

Aromatic Hydrocarbons as Indicators of Origin and Maturation for Light Oils from Panyu Lower Uplift in Pearl River Mouth Basin

Aromatic fractions of six light oils and two source rock samples from Panyu（番禺） lower uplift of Pearl River Mouth basin were analyzed using GC-MS（gas chromatography-mass spectrometric） technique.Thirteen aromatic series of hydrocarbons detected such as biphenyls,naphthalenes,phenanthrenes,dibenzothiophenes（more than two hundred aromatic hydrocarbon compounds） were used to analyze the origin and maturity of the light oils.This study indicates that the distribution of aromatic hydrocarbon compounds in the light oils of wells L1 and P1 differs from those of wells P2,P3 and P4.The light oil samples from wells L1 and P1 contain more dibenzofuran and fluorence hydrocarbons and less naphthalene hydrocarbons.The contents of fluorene,dibenzothiophene and dibenzofuran in the two groups of light oils also show their difference in sedimentary environment.Moreover,the diversity of the relative distributions of biphenyl and naphthalene is apparent between the two groups of light oils.As mentioned above,the origin of the light oils from wells L1 and P1 varies from that of wells P2,P3 and P4.According to the result of oil-source correlation,the light oils from wells P2,P3 and P4 mainly originated from the source rocks in the Enping（恩平） Formation.Accordingly,the light oils from wells L1 and P1 may have been derived from the lacustrine shales in the Wenchang（文昌） Formation or from the mixed source of the Wenchang Formation and the Enping Formation.Applying maturity parameters of methylnaphthalenes,methylphenanthrenes and methyldibenzothiophenes from the aromatic hydrocarbons to the study of the maturity of light oils from Panyu lower uplift indicates that the maturity has reached the high mature stage.

Alkyl Naphthalenes and Phenanthrenes:Molecular Markers for Tracing Filling Pathways of Light Oil and Condensate Reservoirs

Condensates and light oils are generally characterized by high maturity, low concentration of sterane and terpane biomarkers and low content of non-hydrocarbon fraction. As a result, some commonly-used sterane, terpane and carbazole migration parameters in conventional oil reservoirs may have a certain limitation in condensate and light oil reservoirs for their poor signal-noise ratios in the gas chromatography-mass spectrometry （GC-MS）. Naphthalene, phenanthrene and their methylated substituents, however, are present in significant concentrations in condensates and light oils. Taking the Fushan depression （in the Beibuwan Basin, Northern South China Sea） as an example, this paper attempts for the first time to use polycyclic aromatic hydrocarbon （PAH）-related parameters to trace migration directions and filling pathways for condensate and light oil reservoirs. The result shows that TMNr （i.e. 1, 3, 7-TMN/（1, 3, 7-TMN ＋ 1, 2, 5-TMN）, TMN： trimethylnaphthalene））, MPI-1 （i.e. 1.5×（2-MP ＋ 3-MP）/（P ＋ 1-MP ＋ 9-MP）, P： phenanthrene MP： methyiphenanthrene）, MN/DMN （∑methylnaphthalene/∑dimethylnaphthalene, %） and MN/TMN （∑nethylnaphthalene/∑trimethylna- phthalene, %） can be used to trace the filling pathways of condensate and light oil reservoirs. These parameters, together with geological consideration and other bulk oil properties （e.g. the gas to oil ratio and density）, suggest that the condensates and light oils in the Huachang oil and gas field are mainly sourced from the Bailian sag that is located to the northeast of the Huachang uplift in the Fushan depression.

Oxidization characteristics and thermal miscible flooding of high pressure air injection in light oil reservoirs

Physical modeling,numerical simulation and field case analysis were carried out to find out the subsurface thermal oxidation state,thermal oxidation front characteristics and production dynamic characteristics of high pressure air injection thermal oxidation miscible flooding technology.The lighter the composition and the lower the viscosity of the crude oil,the lower the fuel consumption and the combustion temperature are.The thermal oxidation front of light oil and volatile oil can advance stably,and a medium-temperature thermal oxidation stable displacement state can be formed in the light oil reservoir under high pressure conditions.With strong thermal gasification and distillation,light oil and volatile oil are likely to form a single phase zone of gasification and distillation with thermal flue gas at the high-temperature and high-pressure heat front,finally,an air-injection thermal miscible front.In light oil reservoirs,the development process of high-pressure air-injection thermal miscible flooding can be divided into three stages:boosting pressure stage,low gas-oil ratio and high-efficiency stable production stage and high gas-oil ratio production stage.Approximately 70%of crude oil is produced during the boosting pressure stage and low gas-oil ratio high-efficiency and stable production stage.

Correction Method of Light Hydrocarbons Losing and Heavy Hydrocarbon Handling for Residual Hydrocarbon (S_1) from Shale

In China, hot researches on shale oil were raised by the important breakthrough of shale oil in America. Obviously, the first important issue is the actual shale oil resource potential of China, and the selection of the key appraisement parameter is vital to the shale oil resource amount. Among the appraisement parameters, the oil content parameter（S1） is the key one, but the evaluation result is generally lower because of light hydrocarbon losing and heavy hydrocarbon handling. And the more important thing is that the light hydrocarbon with small molecular weight is more recoverable, and therefore its amount is important to the total shale oil yields. Based on pyrolysis experiments and the kinetic model of hydrocarbon generation, correction factors and a model of light hydrocarbon losing and heavy hydrocarbon handling were established. The results show that the correction factor of heavy hydrocarbon handling is 3.2, and that of light hydrocarbon losing is controlled by kerogen type, maturity and hydrocarbon generation environment（closed or open）.

Low-temperature oxidation of light crude oil in oxygen-reduced air flooding

Light crude oil from the lower member of the Paleogene Xiaganchaigou Formation of Gaskule in Qinghai Oilfield was selected to carry out thermal kinetic analysis experiments and calculate the activation energy during the oil oxidation process.The oxidation process of crude oi l in porous medium was modeled by crude oil static oxidation experiment,and the component changes of crude oil before and after low-temperature oxidation were compared through Fourier transform ion cy-clotron resonance mass spectrometry and gas chromatography;the dynamic displacement experiment of oxygen-reduced air was combined with NMR technology to analyze the oil recovery degree of oxygen-reduced air flooding.The whole process of crude oil oxidation can be divided into four stages:light hydrocarbon volatilization,low-temperature oxidation,fuel deposition,and high temperature oxidation;the high temperature oxidation stage needs the highest activation energy,followed by the fuel deposition stage,and the low-temperature oxidation stage needs the lowest activation energy;the concentration of oxygen in the reaction is negatively correlated with the activation energy required for the reaction;the higher the oxygen concentration,the lower the average activation energy required for oxidation reaction is;the low-temperature oxidation reaction between crude oil and air generates a large amount of heat and CO,CO_(2) and CH4,forming flue gas drive in the reservoir,which has certain effects of mixing phases,reducing viscosity,lowering interfacial tension and promoting expansion of crude oil,and thus helps enhance the oil recovery rate.Under suitable reservoir temperature condition,the degree of recovery of oxygen-reduced air flooding is higher than that of nitrogen flooding for all scales of pore throat,and the air/oxygen-reduced air flooding de-velopment should be preferred.

Cocracking and Separate Cracking of Straight-Run Gasoline and Light Gas Oil

This paper presents experimental results of cocracking of straight-run gasoline (SRG) and light gaS oil (LGO) in an improved pulsed-micro-pyrolyzer. It is shown that there are negative opergistic effect on the yields and selectivities of ethylene and propylene in cocracking. The difference in coking tendencies betWeen the cocracking and the separate cracking is compared as well.

Research progress and key issues of ultra-deep oil and gas exploration in China

Based on the recent oil and gas discoveries and geological understandings on the ultra-deep strata of sedimentary basins, the formation and occurrence of hydrocarbons in the ultra-deep strata were investigated with respect to the processes of basin formation, hydrocarbon generation, reservoir formation and hydrocarbon accumulation, and key issues in ultra-deep oil and gas exploration were discussed. The ultra-deep strata in China underwent two extensional-convergent cycles in the Meso-Neoproterozoic Era and the Early Paleozoic Era respectively, with the tectonic-sedimentary differentiation producing the spatially adjacent source-reservoir assemblages. There are diverse large-scale carbonate reservoirs such as mound-beach, dolomite, karst fracture-vug, fractured karst and faulted zone, as well as over-pressured clastic rock and fractured bedrock reservoirs. Hydrocarbons were accumulated in multiple stages, accompanied by adjusting and finalizing in the late stage. The distribution of hydrocarbons is controlled by high-energy beach zone, regional unconformity, paleo-high and large-scale fault zone. The ultra-deep strata endow oil and gas resources as 33% of the remaining total resources, suggesting an important successive domain for hydrocarbon development in China. The large-scale pool-forming geologic units and giant hydrocarbon enrichment zones in ultra-deep strata are key and promising prospects for delivering successive discoveries. The geological conditions and enrichment zone prediction of ultra-deep oil and gas are key issues of petroleum geology.

Oil accumulation related to migration of source kitchens in the Lukeqin structural belt, Turpan-Hami Basin, China

The Lukeqin structural belt is the main heavy oil accumulation zone in the Turpan-Hami Basin. The recent discovery of light oil in the Triassic indicates that there may be multiple source kitchens contributing to the oil accumulation. According to oil geochemical analysis and oil-source correlation, the oil in deep and shallow reservoirs of the Lukeqin Oilfield presents different physical and saturated hydrocarbon mass spectrum characteristics. The Triassic heavy oil is from the northern Upper Permian lacustrine source rocks, and the light oil represented by the Yudong-9 Well is from the northwestern Lower Jurassic coal-measure source rocks. The timing of oil charging was determined by K/Ar isotope dating, reservoir fluid inclusion analysis and the evolution history of different source rocks. In summary, the accumulation process consists of two stages. From the end of Triassic to early Jurassic, the northern Permian source kitchen generated a considerable amount of oil, which was finally degraded to heavy oil, migrated to the south and then accumulated. The northwestern Jurassic coal-measure source kitchen began to generate oil at the end of Cretaceous, while the northern source kitchen could only generate a little hydrocarbon. The heavy oil and the light oil have different source rock locations, migration directions and accumulation times. The migration of hydrocarbon source kitchens affects the distribution of heavy oil and light oil reservoirs at the present time.

Fluid Catalytic Cracking Technology for Maximum Gasoline Production

Increasing gasoline production in FCC unit can improve the utilization efficiency of petroleum resources and gain economic benefit.This paper discusses the technical principles for increasing FCC gasoline yield from the aspects of feedstock properties,operating conditions,LCO(light cycle oil)recycling,catalyst selection and reactor type,and illustrates the industrial application examples for maximizing gasoline production.The technical measures,such as optimizing the feedstock,properly increasing the catalyst activity and reaction temperature,recycling LCO or hydrotreated LCO,applying high gasoline yield catalyst,and adopting the two-zone riser reactor,are proposed to enhance the gasoline yield.

Hydrotreating of light gas oil using a NiMo catalyst supported on activated carbon produced from fluid petroleum coke

Nitric acid functionalized steam activated carbon （NAFSAC） was prepared from waste fluid petroleum coke （FPC） and used as a support material for the synthesis ofa NiMo catalyst （2.5 wt-% Ni and 13 wt-% Mo）. The catalyst was then used for the hydrotreatment of light gas oil. The support and catalysts were characterized by Brunauer-Emmett-Teller （BET） gas adsorption method, X-ray diffraction, H2-temperature programmed reduction, NH3-temperature programmed desorption, CO-chemisorption, mass spetrography, scanning electron microscopy （SEM）, Boehm titration, and Fourier transform infrared spectroscopy （FTIR）. The SEM results showed that the carbon material retained a needle like structure after functionalization with HNO3. The Boehm titration, FTIR, and BET results confirmed that the HNO3 functionalized material had moderate acidity, surface functional groups, and mesoporosity respectively. The produced NAFSAC had an inert nature, exhibited the sink effect and few metal support interactions, and contained functional groups. All of which make it a suitable support material for the preparation of a NiMo hydrotreating catalyst. Hydrotreating activity studies of the NiMo/NAFSAC catalyst were carried out under industrial operating conditions in a laboratory trickle bed reactor using coker light gas oil as the feedstock. A parallel study was performed on the hydrotreating activity of NiMo/7-A1203 as a reference catalyst. The hydrodesulfurization and hydrodenitrogena- tion activities of the NiMo/NAFSAC catalyst were 62% and 30%, respectively.

Effect of reservoir heterogeneity on air injection performance in a light oil reservoir

Air injection is a good option to development light oil reservoir.As well-known that,reservoir heterogeneity has great effect for various EOR processes.This also applies to air injection.However,oil recovery mechanisms and physical processes for air injection in heterogeneous reservoir with dip angle are still not well understood.The reported setting of reservoir heterogeneous for physical model or simulation model of air injection only simply uses different-layer permeability of porous media.In practice,reservoir heterogeneity follows the principle of geostatistics.How much of contrast in permeability actually challenges the air injection in light oil reservoir?This should be investigated by using layered porous medial settings of the classical Dykstra-Parsons style.Unfortunately,there has been no work addressing this issue for air injection in light oil reservoir.In this paper,Reservoir heterogeneity is quantified based on the use of different reservoir permeability distribution according to classical Dykstra-Parsons coefficients method.The aim of this work is to investigate the effect of reservoir heterogeneity on physical process and production performance of air injection in light oil reservoir through numerical reservoir simulation approach.The basic model is calibrated based on previous study.Total eleven pseudo compounders are included in this model and ten complexity of reactions are proposed to achieve the reaction scheme.Results show that oil recovery factor is decreased with the increasing of reservoir heterogeneity both for air and N2 injection from updip location,which is against the working behavior of air injection from updip location.Reservoir heterogeneity sometimes can act as positive effect to improve sweep efficiency as well as enhance production performance for air injection.High O2 content air injection can benefit oil recovery factor,also lead to early O2 breakthrough in heterogeneous reservoir.Well-type does not show great effect on production performance for air injection in extreme heterogeneous reservoir.While adopting horizontal producer is favourable to promote production performance for air injection in homogenous reservoir.

Origin,Distribution and Geochemical Significance of Isopropyltoluene Isomers in Crude Oil

With comprehensive two-dimensional gas chromatography linked to time-of-flight mass spectrometry(GC × GC-TOFMS),ten light hydrocarbon(LH) compounds were qualitatively and quantitatively studied in light hydrocarbons(LHs) components of crude oils.For significant differences in the concentrations of 3-isoproyltoluene(3-iPT),4-isoproyltoluene(4-iPT) and 2-isoproyltoluene(2-iPT) in crude oils,and the 2-iPT probably derived mainly from similar skeleton monocyclic terpenoids via dehydrogenation and aromatization,the ratios of(3+4)-/2-iPT(iPTr),3-/2-iPT(iPTr1) and 4-/2-iPT(iPTr2) are proposed to distinguish the organic matter origin of crude oils.Relatively higher iPTr(>8.0),iPTr1(>7.0) and iPTr2(>4.0) values indicate that crude oils are sourced from the co-contribution of lower aquatic organisms,bacteria,algae,and terrestrial higher plants,whereas lower iPTr(<5.0),iPTr1(<3.0),iPTr2(<2.0) values suggest that crude oils originated from terrestrial higher plants.The iPTr,iPTr1,and iPTr2 values show notable distinction which is mainly controlled by 2-iPT concentrations,while the concentrations of 3-iPT and 4-iPT have similar distribution range in all studied oils.The 2-iPT depleted in marine oils from the Tarim Basin and lacustrine oils from the Beibuwan Basin is less than 0.30 mg/g LHs,whereas 2-iPT enriched in swamp oils from the Tarim Basin is greater than 0.50 mg/g LHs.The iPTr,iPTr1,and iPTr2 ratios and 2-iPT concentrations can be used to distinguish the organic matter origin of crude oils,especially for light oils and condensates with low concentrations of biomarkers.