A breakthrough of researching reservoir adsorption gas and its significance

GC-C-MS on linear isotope analysis equipment makes it possible to measure the hydrocarbon gases at the level of 10 -3-10 -2 μL- By applying this technique the carbon isotopes of C1-C3 of the adsorbed gas from the Triassic oil sand bed of the Aican-l Well in the Turpan-Hami basin were analysed. The δ13C values of C1-C3, are -55.1‰, -38.6‰ and -35.0‰ respectively. In terms of geochemical characteristics of natural gases and crude oils, in combination with basinal geological backgrounds, it is considered that the reservoir adsorbed gas was formed by crude-oil biodegradation, absorbed by reservoir rocks and its oil-gas source is related with the Permain (perhaps including the Carboniferous). The adsorbed gas is obviously different from the Jurassic coal-generated oil and gas.     

Oil cracking to gases： Kinetic modeling and geological significance

A Triassic oil sample from LN14 of Tarim Basin was pyrolyzed using the sealed gold tubes at 200-620℃under a constant pressure of 50 MPa. The gaseous and residual soluble hydrocarbons were analyzed. The results show that the cracking of oil to gas can be divided into two distinct stages: the primary generation of total C1-5 gases from liquid oil characterized by the dominance of C2-5 hydrocarbons and the secondary or further cracking of C2-5 gases to methane and carbon-rich matters leading to the progressive dryness of gases. Based on the experimental data, the kinetic parameters were determined for the primary generation and secondary cracking of oil cracking gases and extrapolated to geological conditions to predict the thermal stability and cracking extent of crude oil. Finally, an evolution model for the thermal destruction of crude oil was proposed and its implications to the migration and accumulation of oil cracking gases were discussed.     

Stable carbon and hydrogen isotopic fractionations of alkane compounds and crude oil during aerobically microbial degradation

Petroleum-related environmental pollution has be-come a global concern with the industrial and economicaldevelopment, causing serious ecological risks and threat-ening natural resources and human health. Therefore, it isimportant to characterize contaminants and thereby iden-tify unambiguously the sources of contaminants, not onlyfor the purpose of settling disputes related to liability butmore importantly, for selecting appropriate responses andtaking effective cleanup precautions[1]. Chemica…     

东营凹陷北部深洼带天然气成因类型的鉴别分析

东营凹陷北部深洼带发现了一系列高产天然气流,成为富油凹陷油气勘探的重要突破,它们是源岩热解气还是原油裂解气,成为勘探家争论的问题。通过民丰地区发现的天然气地质和地球化学分析,特别是烃源岩和原油生气的模拟实验,发现两种成因天然气的鉴别标志,源岩热解气,ln(CC5/nC6)<-1、(MCC5+CC6)/nC6<0.8、(CC5+MCC5+CC6)/(nC5+nC6)<0.5、DMCC5/CC5>0.6和甲苯/苯>1.1,而原油裂解气与之相反;民丰天然气主要来自沙四段烃源岩热解气,其次来自原油裂解气。     

川东飞仙关组烷烃气碳同位素特征与成因分析

飞仙关组作为川东主力气层,陆续已经发现了普光、毛坝、东岳寨、渡口河等一系列大中型气藏,展示了极其重要的战略地位。目前常规的组成分析方法已经不能满足该层天然气类型及成因的判别要求。通过分析烷烃气碳同位素特征,判识天然气类型、分析其成因机制。实验分析显示部分样品C_1~C_3烷烃气的碳同位素比值呈δ~(13)C_1δ~(13)C_2δ~(13)C_3分布(倒转),显示为多源、多期天然气混入。同时根据C_1/C_2+C_3与δ~(13)C_1及ln(C_1/C_2)与In(C_2/C_3)的值域变化特征,最终判断川东大多气藏以原油裂解气为主,混入一定的煤型气。川东飞仙关组古油藏于晚侏罗世沉积期,其埋藏深度介于5 300~8 200 m之间,油藏温度普遍超过150℃,油发生热裂解,生成烷烃气及沥青,持续时间大于30 Ma。     

The role of reservoir mediums in natural oil cracking: Preliminary experimental results in a confined system

Large amounts of data regarding the influence of temperature and pressure on the thermal stability of crude oil have been published; however, the role of reservoir mediums has received little attention. Experiments involving oil cracking in the presence of montmorillonite, illite, calcite, quartz and water were conducted in closed gold tubes to investigate the effects of these reservoir mediums on oil destruction. This was done by screening variations in the chemical and stable carbon isotopic components of nC₁₀₊ and gasoline-range hydrocarbons (nC_8?) present in various systems. Results indicated that reservoir mediums have an active role in oil cracking under experimental conditions. The concentrations of nC₁₀₊ in the cracked residues progressively decreased in systems containing oil+water+illite, oil+water+montmorillonite, oil+water, oil+water+quartz and oil+water+calcite. In comparison with the system containing oil+water, our results indicated a retardation effect for oil cracking in systems in the presence of illite and montmorillonite, and an acceleration effect on oil destruction in systems in the presence of calcite and quartz. nC₁₀₊ became increasingly depleted in ¹³C in systems with oil+water+illite, oil+water+calcite, oil+water+montmorillonite, oil+water+ quartz and oil+water. No obvious correlation was observed between concentrations and stable carbon isotopic components of nC₆-nC₈ and nC₁₀₊ in the individual systems. The discrepancies in chemical and stable carbon isotopic components of nC₆-nC₈ and nC₁₀₊ in the pyrolyzed residues highlighted the important role of reservoir mediums to control carbon-carbon cleavage of nC₁₀₊ and then the isomerization, cyclolization and aromatization reactions; as well as governing the occurrence and thermal destruction of nC₆-nC₈ under experimental conditions. This research may have critical implications in reconstructing chemical kinetic models for natural oil cracking.     

Discussion of gas enrichment mechanism and natural gas origin in marine sedimentary basin, China

There are abundant natural gas resources in Chinese marine sedimentary basin. The exploration hot shots of natural gas are the Palaeozoic marine strata here in recent years, and several large scale gas fields have been discovered. Chinese Palaeozoic high-post matured and coal measure hydrocarbon source rocks are mainly prone to gas generation in the present. This research considered that gas source rocks and TSR are the key cause of gas enrichment of marine strata. High-quality argillaceous and coal measure hydrocarbon rocks are distributed widely in the Palaeozoic marine strata, which have been in highly matured phase in the present. The argillaceous source rock generally contains various sulfates that could accelerate crude oil cracking to gas for TSR occurrence, and coal measure source rock mainly generates gas, so Chinese marine basin gives priority to accumulating gas. Marine strata have not founded oil reservoirs in the Sichuan Basin and Ordos Basin, and they consist mainly of dry gas. Marine natural gases are the mixed gases of oil cracking gas and coal-formed gas in a general way, oil cracking gases contain usually some H2S and CO2. Hydrocarbon carbon isotopes are very complicated, and methane and ethane isotopic values bear apparent reversal caused by thermal evolution and mixing among different genetic types of natural gas. Coal-formed gases are the main component of Chinese marine natural gas. The Upper Permian of the Sichuan Basin and the Carboniferous-Permian of the Ordos Basin coal measure hydrocarbon source rock present large hydrocarbon generation po- tential, which are the prospecting highlight of marine natural gas hereafter. Oil cracking gas exploration will be paid much attention to in the Tarim Basin because of the lack of coal measure hydrocarbon source rock.     

Discussion of gas enrichment mechanism and natural gas origin in marine sedimentary basin,China

There are abundant natural gas resources in Chinese marine sedimentary basin. The exploration hot shots of natural gas are the Palaeozoic marine strata here in recent years, and several large scale gas fields have been discovered. Chinese Palaeozoic high-post matured and coal measure hydrocarbon source rocks are mainly prone to gas generation in the present. This research considered that gas source rocks and TSR are the key cause of gas enrichment of marine strata. High-quality argillaceous and coal measure hydrocarbon rocks are distributed widely in the Palaeozoic marine strata, which have been in highly matured phase in the present. The argillaceous source rock generally contains various sulfates that could accelerate crude oil cracking to gas for TSR occurrence, and coal measure source rock mainly generates gas, so Chinese marine basin gives priority to accumulating gas. Marine strata have not founded oil reservoirs in the Sichuan Basin and Ordos Basin, and they consist mainly of dry gas. Marine natural gases are the mixed gases of oil cracking gas and coal-formed gas in a general way, oil cracking gases contain usually some H2S and CO2. Hydrocarbon carbon isotopes are very complicated, and methane and ethane isotopic values bear apparent reversal caused by thermal evolution and mixing among different genetic types of natural gas. Coal-formed gases are the main component of Chinese marine natural gas. The Upper Permian of the Sichuan Basin and the Carboniferous-Permian of the Ordos Basin coal measure hydrocarbon source rock present large hydrocarbon generation potential, which are the prospecting highlight of marine natural gas hereafter. Oil cracking gas exploration will be paid much attention to in the Tarim Basin because of the lack of coal measure hydrocarbon source rock.     

Groundbreaking gas source rock correlation research based on the application of a new experimental approach for adsorbed gas

Many years of experimentation have led to the development and improvement of equipment and methods used to make gas source rock correlations.By crushing samples using a ball mill and directly collecting adsorbed gases in the absence of aqueous media under high vacuum conditions,most possible interference factors,such as atmospheric pollution,crushing-induced pyrolysis,and gas collection by aqueous media are eliminated.This greatly enhances the volume percentage of hydrocarbon gas in the acquired adsorbed gases,with maxima up to more than 80%.The actual measurement of carbon isotopic series can be carried out to such an extent as to be δ13C1-δ13C5.A preliminary study using newly established equipment and methods has indicated the following.(1) The carbon isotopic composition of ethane in adsorbed gases on hydrocarbon source rocks can be used to distinguish the types of source rocks.This is consistent with results obtained by using organic geochemical parameters for source rocks,and illustrates that it is highly feasible to use the carbon isotopic composition of ethane in natural gases as a parameter for distinguishing the types of source rocks.(2) The thermal evolution degree(Ro) of hydrocarbon-source rocks calculated in terms of the carbon isotopic composition of methane in adsorbed gases on hydrocarbon source rocks agrees well with the vitrinite reflectance actually measured in the source rocks.This confirms the reliability of the relationship between the carbon isotopic composition of methane in natural gases and the thermal evolution degree determined using statistics.(3) Finally,a direct gas source correlation method for natural gases has been established,and the expression of log Ro vs.δ13C1 established in terms of actually measured δ13C1 values of methane in absorbed gases.Ro values of hydrocarbon source rocks have been established as well,thus creating favorable conditions for precise oil-and-gas source correlations in exploration areas.     

Oil cracking： An important way for highly efficient generation of gas from marine source rock kitchen

The potentials of gas generation by kerogen in the late period and by crude oil cracking are closely related to the origin of natural gas in the high- to over mature marine area and their exploration perspectives. The carbon structure of kerogens, with different types and at different evolution stages, have been experimentally studied using the high magnetic field solid ^13C nuclear magnetic resonance technique in order to determine the oil and gas potential of kerogens. Results show that the contents of gas potential carbon（GPC） of types Ⅰ, Ⅱ, Ⅲ kerogens at the high- to over mature stage are very low, indicating their weak gas-generating capacity and limited gas production; however, the content of oil potential carbon（OPC） of the low mature type Ⅰ kerogen is much higher, implying that a large amount of crude oil generated during the oil-generating period will be the material for later gas generation by oil cracking. The kinetic experiment of gas generation by crude oil cracking shows that, when the temperature is about 160℃（R0=1.6%）, the crude oil will start to produce large amounts of gas; the temperature range for major gas generation of crude oil is higher than that of the kerogens, and the gas production is 2 to 4 times higher than that of kerogens. The natural gas derived from oil cracking （called oil-cracked gas） is much abundant in methyl hexamethylene, which is quite different from the natural gas produced by thermal degradation of kerogens （named kerogen degradation gas） at high- to over mature stage.     

温度对原油四组分高压热解性能的影响

在30 MPa压力下对塔里木原油四组分进行封闭体系的热解实验,通过气相色谱(GC)和气相色谱/质谱(GC/MS)分别对原油四组分热解反应的气体产物及饱和分热解过程的液态产物进行分析.结果表明:原油四组分热解气体产物中C1组分产率明显高于C2~C5组分,气体产物中C1~C2组分的产率及气体总产率随热解温度升高而增加;在温度高于450℃时,四组分总产气率的大小顺序为:沥青质饱和分芳香分胶质.随热解温度升高,饱和分中的主要组分C12~C18的反应程度加剧.在410℃时,饱和分热解以裂解反应为主,在大于490℃时,裂解和缩合反应程度都在增加,导致气相产物的产率提高及液相产物中主要组分向大分子烃类转移;且温度升高,液态产物分布的离散程度增加.     

东濮凹陷北部地区古近系油型气成因类型及分布特征

以热压模拟实验模拟东濮凹陷干酪根热裂解和原油热裂解过程,分析干酪根热裂解气和原油裂解气组分特征的差异,以此建立干酪根热裂解成因气和原油裂解成因气的判识方法;结合东濮凹陷北部地区天然气碳同位素及天然气组分数据,对研究区油型气进行划分,进而探讨干酪根热裂解气与原油裂解气的分布特征。结果表明,研究区古近系油型气分为干酪根热裂解气与原油裂解气,干酪根热裂解气具有相对较高的C1/C2值和较低的C2/C3值特征,而原油裂解气则与之相反。干酪根热裂解气和原油裂解气的分布存在明显差异:前者分布范围更广,后者更近于洼陷中心分布,两者分布的差异性与其生成及成藏条件差异有关。根据干酪根热裂解气与原油裂解气分布特点,推测在邻近洼陷中心区具有良好的干酪根裂解成气及原油裂解成气的条件和油型气勘探前景。     

Identification of the Kukersite-type source rocks in the Ordovician Stratigraphy from the Tarim Basin, NW China

Due to the importance of the Gloeocapsomorpha Prisca （G. prisca）-enriched source rocks, which belong to Kukersite-type source rocks in the Lower Paleozoic Ordovician strata, it has received great attentions during the petroleum exploration as to whether there are the Kukersite-type source rocks developed in the major hydrocarbon source strata of the Upper and Middle Ordovician in the Tarim Basin. Using pyrolysis-gas chromatography-mass spectrography to analyse kerogens from source rocks in the lime- mud mound with moderate maturity, study reveals that there are the Kukersite-type source rocks in the Ordovician strata of the Tarim Basin. The pyrolysis products showed a low content of 〉n-C19 normal alkanes with a significant odd-even predominance between n-C13 and n-Cl7, long-chain alky substituted alkylbenzene and alkylthiophene isomers and distinctive distribution of 5-N- alkyl-1, 3-Benzenediol and its homologous. Based on the geographic environment characteristics of G. Prisca, the molecular dis- tributions of crude oil from the Lower Paleozoic petroleum systems in the Tarim Basin and characteristics of kerogen pyrolysis products from the Middle and Upper Ordovician source rocks, the results suggested that it is less possible to develop the G. Pris- ca-enriched Kukersite-type source rocks in the major hydrocarbon source rocks in the Middle and Upper Ordovician strata in the Tarim Basin. However, the benthic macroalga and planktonic algae-enriched source rocks are the main contributors.     

Pyrolysis of oil at high temperatures: Gas potentials, chemical and carbon isotopic signatures

Although the gas cracked from oil has been believed to be one of the important sources in highly ma-tured marine basins, there are still some debates on its resource potentials and chemical and isotopic compositions. In this study a Cambrian-sourced marine oil sample from the Silurian reservoir of well TZ62 in the central Tarim basin was pyrolyzed using sealed gold tubes with two different pyrolysis schemes: continuous pyrolysis in a closed system and stepwise semi-open pyrolysis. The results show that the maximum weight yield of C_1–5 gases occurs at EasyRo=2.3% and the residual gas poten-tial after this maturity is only 43.4 mL/g, about 12% of the yield of 361 mL/g at EasyRo=2.3%. Combined with the results of kinetic modeling, the main stage of gas generation from oil cracking is believed within the EasyRo=1.6%―2.3%. The increase in the volume yield of C_1–5 gases at EasyRo>2.3% in a closed system is mainly related to the re-cracking of previously formed C_2–5 wet gases, not the direct cracking of oil. The stepwise pyrolysis experiments show that the gas from the cracking of residual oil at EasyRo>2.3% is characterized by very high dryness index (higher than 92%) and heavy methane carbon isotopes ranging from -28.7‰ to -26.7‰, which is quite different from the gases from the con-tinuous pyrolysis in a closed system. The kinetic modeling of methane carbon isotope fractionation shows that the carbon isotopes of methane within the main stage of gas generation (EasyRo<2.3%) are far lighter than the carbon isotopes of the precursor oils under a geological heating rate of 2 ℃/Ma. The above observations and results provide some new clues to the accurate recognition and objective re-source evaluation of oil cracking gas in highly mature marine basins.     

挥发性油藏酸气回注的最小混相压力与组分优化

高含H_2S和CO_2酸性气体的低渗透挥发性油藏在开发过程中,H_2S和CO_2会以溶解气的形式被采出,并占有较高的摩尔分数。分离器条件下的气态轻烃通过回注地层,在油藏压力高于最小混相压力(MMP)时达到混相驱动,一方面可以显著提高驱油效率,另一方面可以起到减缓压力衰竭的目的。H_2S和CO_2作为污染气体,分离和回收成本较高;而与烃气一同回注地层势必会对MMP产生影响。因此,需要研究酸性气体对溶解气回注MMP的影响规律并且合理地优化回注气组分。在对目标区块原油组分拟合重组的基础上,通过混合单元格法预测MMP,研究了溶解气主要组分的混相能力以及H_2S和CO_2对烃气驱MMP的影响规律,通过正交试验方法优化了注入气比例。结果表明:作为酸性杂质气体H_2S和CO_2具有较强的混相能力,可以降低注气MMP;最优注气形式为溶解气直接回注地层。     

CO2混相调节剂驱油机理室内研究

为了深入了解混相调节剂降低CO_2/原油最小混相压力的作用,测试CO_2混相调节剂降低最小混相压力的机理,开展了室内实验,并深入研究调节剂的效果。实验结果表明,混相调节剂可以降低CO_2/原油表面张力、促进CO_2抽提原油轻质组分效果、增加CO_2在原油中溶解度、降低原油黏度的作用;其中,主要的机理为降低表面张力和提高抽提轻质组分效果;当原油中调节剂质量浓度达0.3%以上,气液表面张力消失,达到混相;加入调节剂后,采出端气体突破时,CO_2萃取、抽提轻质烃体积百分数增加14倍以上。调节剂作用机理研究,深入了对调节剂改善CO_2驱油效果的认识,并对进一步筛选和研发新型调节剂具有指导意义。     

川东沥青来源分析和结构分析

宣南圈闭中探明了石炭系、Ch-F等大规模气藏,前景可观,但对于焦质烃的气源研究还存在争议。文章对宣南圈闭焦质烃进行碳同位素、饱合烃组分及生物标志物进行分析,研究其成因和气源类型,从而最终确定其主力烃源岩。Ch－F储层焦质烃集中分布在27.54‰～29.4‰,最大相差为1.8‰,而石炭层焦质烃碳同位素集中于-26.6‰～-29.7‰之间;正构烷烃的碳数分布模式相似,都呈单峰型分布,CH-F焦质烃正构烷烃主峰碳数在C20附近,而石炭系黄龙组焦质烃主峰碳数在C18附近,石炭系演化程度稍高。综合认为,石炭系与Ch-F焦质烃具有同源性,天然气主要为原油高温裂解生成,认为固体焦质烃及天然气主要来源于志留系龙马溪组泥岩,并有少量的龙潭组干酪根裂解生气的混入。     

反应温度对催化汽油窄馏分芳构化的研究

为了使催化裂化(FCC)汽油中烯烃含量满足国家的新标准的要求,需要将汽油中的烯烃转化为异构烷烃和芳烃.以兰炼催化汽油窄馏分为原料,采用小型固定流化床为芳构化反应装置,考察了反应温度对催化汽油窄馏分芳构化产物各组分的增加率、气体产物组成和液体产物组成的影响规律.实验结果表明,对于同一窄馏分,在相同碳数的条件下,随反应温度的升高,各组分的增加率逐渐增加,且反应温度越高,其增加的幅度越大.对于同一种馏分油,随着反应温度的升高,干气、液化气和焦炭产率逐渐增大,而液体产率逐渐减少,芳烃的产率和选择性逐渐增加.在同一温度下,随着馏分变重,干气、液化气和焦炭产率逐渐减少,芳烃、轻油收率和芳烃的选择性逐渐增加,正构烷烃、异构烷烃和烯烃的产率逐渐减少,而芳烃含量迅速增加,环烷烃的含量先增加后变小,存在最大值.     

Mn0.8Zn0.2Fe2O4 nanoparticulates spinel ferrites:An approach to enhance the antenna field strength for improved magnitude versus offset（MVO）

Electromagnetic signals in deep reservoir are very weak so that it is difficult to predict about the presence of hydrocarbon in seabed logging(SBL) environment.In the present work,Mn0.8Zn0.2Fe2O4 nanoferrites were prepared by a sol–gel technique at different sintering temperatures of450 °C,650 °C and 850 °C to increase the strength of electromagnetic(EM) antenna.XRD,FESEM,Raman spectroscopy and HRTEM were used to analyze the phase,surface morphology and size of the nanoferrites.Magnetic properties of the nanoferrites were also measured using an impedance network analyzer.However,nanoferrites sintered at 850 °C with initial permeability of 200 and Q factor of 50 were used as magnetic feeders with the EM antenna.Lab scale experiments were performed to investigate the effect of magnetic field strength in scale tank.SPSS and MATLAB softwares were also used to confirm the oil presence in scale tank.It was observed that the magnitude of the EM waves for the antenna was increased up to 233%.Finally,the correlation values also show 208% increase in the magnetic field strength with the presence of the oil.Therefore,antenna with Mn0.8Zn0.2Fe2O4 nanoferrites based magnetic feeders can be used for deep water and deep target hydrocarbon exploration.     

不同注入气体下低渗油藏注气开发室内评价

为了探索乌石17-2油田注气开发方式可行性以及进一步提高油田开发效果,从室内实验角度出发,对三种气体(N_2、CO_2、烃类气)开展了注气膨胀实验、细管实验、长岩心驱替实验,并进行对比分析及效果评价。研究结果表明:N_2在地层条件下表现为非混相驱,其对原油的降黏及膨胀能力有限,后期气窜明显,注气突破时间较早,突破前采出近90%左右的原油,而突破后基本为无效注气,几无产出。室内驱油效率仅为36.3%,开发效果差。烃类气、CO_2与地层原油相态配伍性要好,最小混相压力低,分别为27.52、27.13 MPa。地层条件下易形成近混相驱,气体突破要晚,气体突破以后仍能采出近30%左右的原油,驱油效率要高于非混相驱近25%,最终驱油效率分别为66.7%、69.0%,开发效果好。烃类气驱、CO_2驱可作为乌石17-2油田低渗强水敏储层优选能量补充方式。