Application of C5—C13 light hydrocarbons in depositional environment diagnosis

Based on the geological background and Gammacerane/C31H（S ＋ R） ratios, source rock depositional environments of the studied oil samples （194） from 13 oilfields were classified into three groups according to salinity： saline-lacustrine facies, fresh to brackish lacustrine facies （including limnetic facies）, and semi-saline to saline facies （including marine facies of the Tarim Basin）. C5-C13 compound groups in the crude oils were separated by GC, and about 286 compounds were qualitatively analyzed. The geochemical application of the C6- C13 compound groups and their ratios between each group with individual carbon number was investigated. Our studies show that （1） C6-C13 compound groups and their ratios in the crude oils could serve as new reliable parameters for oil-oil correlation because the C6- C13 light fractions are the major oil component, especially in light oil or condensate, in which they account for almost 90% of the whole oil; （2） the compound groups of C7 light hydrocarbons in oils derived from different depositional environments with different salinity have different characteristics; （3） C6-C13 compound groups and ratios may be affected by other factors such as maturity, but they are mainly controlled by salinity of depositional waters.     

Pool-formation and secondary change of biodegraded viscous oils: Case study of reservoir section in the Zhengjia-Wangzhuang Oilfield, Jiyang Depression

It is demonstrated by various geochemical indexes that the Zhengjia-Wangzhuang Oilfield with viscous crude oil in the Jiyang Depression has been sourced from the contribution of matured source rocks in the upper Es4. The principal cause leading to the densification of crude oils would be biodegradation, with the degradation level of crude oils being ranked as 2-8; vertically, the biodegradation level increases from the top to bottom of the oil column, with a distinctive biodegradation gradient occurring. Calculated parameters of sterane, terpane and methyl-phenanthrene have indicated that the source-rock's maturity of crude oils and asphaltic sands ranges from 0.7 to 0.9, and based on the calculation of Easy Ro model, the temperature of hydrocarbon generation in the source rock would be within 120-140℃, which coincides with the measurements of reservoir inclusions. The measured homogenization temperature would represent the generation temperature of the source rock, and be fairly different from that of reservoir while being charged with hydrocarbons, which reflects the hydrocarbon-charging to be a fast process, and the period of pool-formation to be consistent with that of peaked generation. According to the evaluation of generation history, the pool-formation could have been occurring in 7-15 Ma. And the biodegradation of crude oils in the study area would be considered to take place in 4-15 Ma based on the examination of biodegradation order and dynamic calculations.     

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.     

Accumulation process and model for the Ordovician buried hill reservoir in the western Lunnan area,the Tarim Basin

The Ordovician buried hill reservoir in the western Lunnan area, a type of dissolved fracture and cavernous reservoir, is mainly composed of heavy oil. The oil is the mixture sourcing from the Middle-Lower Cambrian and Middle-Lower Ordovician, with three stages of pool forming process: (1) the destruction and parallel migration/accumulation during the late Caledonian to early Hercynian; (2) the oil and gas accumulation during the late Hercynian characterized by adjustment upward along faults and parallel migration/accumulation; (3) the formation of heavy oil during the latest Hercynian. The Ordovician buried hill reservoir is affected by the diffusion of light oil and gas but had no hydrocarbon charging during the late Yanshan period to Himalayan period, but in this period, formed the association of heavy oil and dissolved gas cracked from crude oil with dry coefficient of 0.91-0.96. The study on accumulation process of the Ordovician buried hill reservoir has important implications for the exploration potential of early oil and gas accumulation in the cratonic area of the Tarim Basin.     

Accumulation process and model for the Ordovician buried hill reservoir in the western Lunnan area, the Tarim Basin

The Ordovician buried hill reservoir in the western Lunnan area, a type of dissolved fracture and cavernous reservoir, is mainly composed of heavy oil. The oil is the mixture sourcing from the Middle-Lower Cambrian and Middle-Lower Ordovician, with three stages of pool forming process： （1） the destruction and parallel migration/accumulation during the late Caledonian to early Hercynian; （2） the oil and gas accumulation during the late Hercynian characterized by adjustment upward along faults and parallel migration/accumulation; （3） the formation of heavy oil during the latest Hercynian. The Ordovician buried hill reservoir is affected by the diffusion of light oil and gas but had no hydrocarbon charging during the late Yanshan period to Himalayan period, but in this period, formed the association of heavy oil and dissolved gas cracked from crude oil with dry coefficient of 0.91-0.96. The study on accumulation process of the Ordovician buried hill reservoir has important implications for the exploration potential of early oil and gas accumulation in the cratonic area of the Tarim Basin.     

Exploration technology and development trend of Daqing Oilfield

Exploration for oil and deep gas in northern Songliao Basin,complex rift basin—Hailaer Basin,and Yi-Shu Graben in peripheral basin has technical challenge.Researches on supporting technology including seismic acquisition,processing and interpretation,logging and drilling are performed to establish high resolution 3D seismic technology for lithologic reservoir,deep volcanic rock and complex rift basin,reservoir evaluation and stimulation technology for low permeability reservoir,volcanic reservoir and complex rift reservoir,and drilling technology for deep volcanic rock,providing technical support for reserves increase in northern Songliao Basin,large gas reservoirs discovery in deep volcanic rock and exploration progress in complex rift basin.Next-step development trend of exploration technology is proposed to meet the demand of more technical challenges in the future.     

Late Yanshan-Himalayan hydrocarbon reservoir adjustment and hydrothermal fluid activity in the central Tarim Basin

The adjustment of primary hydrocarbon reservoirs in marine formations is an important feature of the oil pools in the Tarim Basin. Large-scale hydrocarbon adjustment is related to the strong regional tectonic movements, which is always accompanied by extensive migration of basin fluids including diagenetic and mineralizing fluids. Organic fluid inclusions are well developed in hydrothermal mine- rals, such as fluorite, which have been found in the dissolution-enlarged fractures or karstification caves in the Ordovician in the central Tarim Basin. Proved by well drilling, the fluorite deposit is good reservoir for oil and gas. So the peculiar accompanied or superimposed relationship between fluorite hydrothermal fluid mineralization and hydrocarbon migration and accumulation exists in the Ordovician in the central Tarim Basin. Considering regional tectonic setting and mineralization condition, through different kinds of analytic methods including electron spin resonance dating, fluid inclusion laser Raman and colonial inclusions hydrocarbon fossil analysis, we proposed that extensive mineralizing fluids and hydrocarbon migration occurred in late Yanshan-Himalayan （110.4-30.8 Ma） period, and Himalayan, especially, is an important period for hydrocarbon accumulation from 34.3 Ma to present.     

Detection of 2-thiaadamantanes in the oil from Well TZ-83 in Tarim Basin and its geological implication

Thermochemical sulfate reduction （TSR） causes increasing of sulfur content in the oils, reduction of oil quality, and produces a toxic and corrosive H2S which may take great adverse effect on health and equipment. Although there are several ways to identify presence of TSR in gas field, yet in the case of oil with low H2S content, it is still very difficult to identify TSR. 2-thiaadamantanes is one of the most effective indicators of TSR. This paper for the first time discovers 2-thiaadamantanes in the oil from Well TZ-83 in Tarim Basin. A silver nitrate silica gel chromatography was used to enrich the oil from low 2-thiaadamantanes content to the level that GC/MS and GC/MS/MS can detect. 2-thiaadamantanes were assigned by comparison of mass spectra with published data, and the fragmental ions in mass spectra were confirmed by MRM mode of GC/MS/MS. H2S gas produced in Tazhong area is thought to be generated from TSR since 2-thiaadamantanes were present in the oil.     

Magnetic and mineralogical characteristics of reservoir rocks in the Yakela oil field, northern Ta rim Basin and their implications for magnetic detection of oil and gas accumulations

The evidence about hydrocarbon migration within reservoir rocks in two wells has been obtained according to results of magnetic and mineralogical analysis of the Kapushaliang Group reservoir rocks from wells S15 and S4 located at the Yakela oil field, Tarim Basin. Results show that the secondary alteration associated with oil and gas accumulations above oil and gas field is predominantly magnetite mineralization, and that sulfur alteration occurs commonly at oil-water boundary and their products are generally pyrite and pyrrhotite, except for magnetite alteration which is closely related with hydrodynamical conditions in situ. The spherical magnetite grains of cauliflower microtexture on surface extracted from oil-bearing cores are secondary magnetite related with hydrocarbon microseep-age and their diameters are usually less than 50 μm.     

MCI分析法在确定油气成藏期次中的应用

介绍了流体包裹体分子成分 (MCI)分析技术及其特点 ,以塔里木盆地英南 2气藏为例 ,利用 MCI技术及其研究方法进行油气成藏期次的研究。对塔里木盆地英南 2现今气藏储层中的烃类 (凝析油与储层沥青 )以及气藏志留系与侏罗系储层成岩矿物中的含油包裹体分子进行了地球化学成分分析 ,对比研究含油包裹体分子地球化学成分和现今气藏中的烃类的分子地球化学成分。研究表明油包裹体分子成分与原油和储层沥青分子成分相似 ,反映它们来源相同 ,是同一期烃类充注的产物 ,英南 2气藏油气成藏期次为一期     

New evidence for the origin of natural gas in Ordos Basin from hydrocarbons of oil water

The chief aim of the present work is to investigate the controversy origin of natural gas in the Ordos Basin by using the hydrocarbons of oil water. New evidence has been found: There is relatively high content of light hydrocarbons and low content of heavy components in the hydrocarbons fraction of oil water in the middle gas field of the Majiagou Formation, Ordovician reservoir. The hydrocarbons of oil water in Well Shan 12 and Well Shan 78 have relatively high abundance of tricyclic terpane. Tricyclic terpane/hopane of the two samples are 1.48 and 0.36, respectively. They also show that pregnane and hompregnane are in relatively high abundance with lower hopane/sterane ratio. Pr/Ph is less than 2.0. These characteristics reflected the source input of marine carbonate sedimentary environment. In contrast, the hydrocarbon of Well Shan 81 is lack of tricyclic terpane series and pregnane. It has a high hopane/sterane ratio and Pr/Ph is 3.27. These parameters are typical character of terrestrial organic matter. Furthermore, the hydrocarbons of oil water in Well Shan 37 and Well Shan 34 is between the two typical situations. They have little content of tricyclic terpanes. They may be derived from a mixing source of marine carbonate and terrestrial organic matter input. Similarly, the maturity parameters approve this suggestion. The samples of Well Shan 12 and Well Shan 78 which derived from marine carbonate have relatively high maturity and samples derived from terrestrial organic matter have lower maturity. The maturity of the hydrocarbons of mixing source is between these two situations. The suggestion coincides with the geological background and source rocks distribution.     

Application of C5-C13 light hydrocarbons in depositional envlrOnment diagnosis

Based on the geological background and Gammacerane/C31H(S+R)ratios,source rock depositional environments of the studied oil samples(194)from 13 oilfields were classified into three groups according to salinity:saline-lacustrine facies,fresh to brackish lacustrine facies(including linmetic facies),and semi-saline to saline facies(including marine facies of the Tarim Basin).C5-C13 compound groups in the crude oils were separated by GC,and about 286 compounds were qualitatively analyzed.The geochemical application of the C6-C13 compound groups and their ratios between each group with individual carbon number was investigated.Our studies show that(1)C6-C13 compound groups and their ratios in the crude oils could serve as new reliable parameters for oil-oil correlation because the C6-C13 light fractions are the major oil component,especially in light oil or condensate,in which they account for almost 90%of the whole oil;(2)the compound groups of C7 light hydrocarbons in oils derived from different depositional environments with different salinity have different characteristics;(3)C6-C13 compound groups and ratios may be affected by other factors such as maturity,but they are mainly controlled by salinity of depositional waters.     

原油热蚀变程度评价指标研究——以准噶尔盆地南缘霍尔果斯和呼图壁油气田为例

 石油的次生变化对石油性质的改造有时会超过有机质来源和热成熟度作用的影响,而热蚀变是地史时期地质体中一种较为常见的次生变化。本文选取准噶尔盆地南缘原油样品系统模拟热蚀变过程,并进行数据分析,从中筛选出相关性良好的菲/甲基菲(P/MP)比值和(3-MP＋2-MP)/(9-MP＋1-MP)比值两项指标,它们能够很好地反映原油热变程度;根据筛选出的这两项指标,制作了判别原油热蚀变程度的图版。应用该图版分析准噶尔盆地南缘霍尔果斯和呼图壁油气田原油热蚀变程度,结果显示,霍尔果斯霍10井原油可能为原生油藏,热变程度较低,而霍浅1和霍002原油可能是由埋藏较深、热变程度高的原始油藏向上运移产生的次生油气藏;准噶尔南缘的安5井、石南31井及呼图壁气田中的呼2井原油处于正常成熟阶段,表明其所处油气藏基本上为原生油气藏。     

扎哈泉地区上干柴沟组砂岩储层致密化原因探讨

扎哈泉上干柴沟组是柴达木盆地致密油勘探潜力区域。上干柴沟组的下段(N_1~1)是典型致密储层,上段(N_1~2)是甜点储层特征。研究表明:构造运动中周围地块的挤压作用对致密储层的形成具有一定控制作用;双物源、近物源及物源变化的沉积作用,致使岩石矿物组份类型多样,岩屑含量高、组份复杂,岩石结构成熟度与成份成熟度低、颗粒沉积分异差,对储层致密化起决定性作用;机械压实、压实-胶结等破坏性成岩作用是储层致密化的主要外部因素,溶蚀作用改善了储层,并应用孔隙度演化模型对各成岩作用孔隙度变化进行了模拟,结果符合地质认识。     

哈萨克斯坦North Nuraly油田侏罗系多尚组储层特征及有利储层预测研究

哈萨克斯坦North Nuraly油田侏罗系多尚组发育一套扇三角洲沉积,为典型的低孔低渗储层。通过扫描电镜、岩石薄片、压汞、X衍射分析等资料首次对研究区储层的岩矿特征、物性以及孔隙结构特征进行了详细研究。研究表明该区储层主要岩石类型为砂砾岩、砂岩、细砂岩,岩石成分成熟度中等、结构成熟度较低;黏土矿物含量高,主要为高岭石和伊利石,对储层伤害较大;其孔隙类型主要为剩余粒间孔,其次为无效的粒内溶孔。进一步研究储层压汞参数和物性特征发现该区储层可细分为Ⅰ、Ⅱ、Ⅲ类,沉积微相控制了其有利储层的展布。通过储层特征及沉积微相之间的关系,预测其有利储层分布范围。结果表明优质储层都集中在水下分流河道、河口砂坝等沉积微相中、较差的储层都集中在远砂坝及碎屑流、浊流砂体中。同时通过最新试油成果,验证了该区有利储层预测的可靠性和可行性,为该地区低孔低渗储层勘探开发提供了扎实的地质理论基础。     

利用流体包裹体研究油藏注入史

油藏注入史分析是一项非常有价值的研究工作,综合利用自生包裹体测温和包裹体中烃类组成特征,结合成岩史、流体史和烃源岩热演化史分析资料,可有效地指明石油向油藏注入的时间、方向和期次,从而建立烃类的成藏模式．这项研究工作对于多期构造运动和多期油气成藏的复杂油气探区具有更加宝贵的实用价值,尤其是将流体包裹体分析技术和精细时—温埋藏史恢复的盆地模拟技术相结合来研究复杂油气探区的油藏注入史,为油气藏形成时期和成藏演化史的研究开辟了新方法和新思路     

基于交叉验证法探究砾岩储集层特征及对化学驱油剂损耗的影响

以克拉玛依油田七东1区克下组砾岩储集层为研究对象,通过X射线衍射、薄片鉴定、孔渗分析等实验,系统开展储集层纵向岩石学特征、孔隙结构特征及宏观物性变化的研究。结合驱油剂动态损耗实验,采用基于交叉验证的逐步回归法,探究储集层特征对驱油剂损耗规律的影响;并应用Petrel建模计算油藏范围内驱油剂损耗量。结果表明:研究区储集层矿物成分成熟度低,结构成熟度低,储集层呈现中-低孔隙度,渗透率纵向变化大,非均质性显著;驱油剂动态损耗量受储集层特征控制,与储集层渗透率、孔隙度、黏土矿物含量等地质特征有较好的相关关系;应用Petrel建模可以实现快速、准确、可视化的油藏范围内驱油剂损耗量计算。在地质条件复杂、驱油剂损耗机理未完全探究清楚的情况下,通过逐步回归法直接从数据中建立模型;并用交叉验证法对模型进行筛选和优化,是驱油剂损耗量计算领域的一个创新应用。     

鄂尔多斯东南部延长组致密油储层微观特征及主控因素

通过岩心观察、薄片鉴定、测井、扫描电镜和恒速压汞实验等资料分析,利用储层地质学等理论技术和知识,对鄂尔多斯盆地东南部延长组致密油储层的岩石结构和组分、孔喉结构和类型、孔渗分布等微观特征及其相关性和主控因素进行研究。延长组致密油储层以细粒长石砂岩为主,岩石结构和成分成熟度较低;平均孔隙半径为10μm且孔隙连通性差,孔隙以粒间孔、长石溶孔和裂缝为主,平均喉道半径为0.41μm,喉道以微细-微喉道为主。孔喉结构的非均质性决定了致密油储层的储集和渗流能力,压汞曲线表现出高排驱压力、中值半径偏小、细歪度、分选中等、退汞效率低的特征显示研究区致密油储层储集能力较强,而渗流能力较差;孔隙度均值为8.5%,渗透率均值为0.69 m D,孔隙度和渗透率表现为线性正相关(R2=0.389),微裂缝的存在使部分样品表现出低孔高渗的特征,储层总体表现为特低孔、超低渗、非均质性强的致密性特点。通过相关性分析,岩石组分主要影响储层的孔隙度,岩石组分中(铁)方解石与孔隙度相关性最好;喉道主要影响储层的渗透率,压汞实验分析表明孔喉大小、分布和连通性特征参数中的孔隙体积、分选系数、排驱压力与渗透率的相关性最好,相关系数均大于0.9,沉积作用(埋深、沉积微相)、成岩作用(压实、胶结和溶蚀)、构造作用等是研究区储层特征的主要控制因素,其中水下分流河道的储层物性最好,是研究区"甜点"储层的指向区;压实作用对储层致密性的贡献大于胶结作用,酸性流体大量生成时储层已在压实和胶结作用下接近致密,因此无法与长石等易溶组分充分接触而发生大规模的次生溶蚀;此外,后期构造运动生成的裂缝由于缺乏酸性流体而无次生溶蚀孔隙生成,储层的致密性无法得到根本性的改善。     

Lacustrine biomass: An significant precursor of high wax oil

Since high wax oils are normally related to terrestrial depositional environment, the concept that high wax oils are derived from terrigenous organic materials has been widely accepted[1,2]. Recently, Hsieh et al.[3,4] studied oils from different depositional environments and ages and suggested that waxy compounds were not restricted to any type of environment or source material. There is a variety of possible sources for the formation of HMWHCs, in-cluding high plant cuticular waxes, blue-g…