Predicting the present-day in situ stress distribution within the Yanchang Formation Chang 7 shale oil reservoir of Ordos Basin, central China

The Yanchang Formation Chang 7 oil-bearing layer of the Ordos Basin is important in China for producing shale oil.The present-day in situ stress state is of practical implications for the exploration and development of shale oil;however,few studies are focused on stress distributions within the Chang 7 reservoir.In this study,the present-day in situ stress distribution within the Chang 7 reservoir was predicted using the combined spring model based on well logs and measured stress data.The results indicate that stress magnitudes increase with burial depth within the Chang 7 reservoir.Overall,the horizontal maximum principal stress(SHmax),horizontal minimum principal stress(Shmin) and vertical stress(Sv) follow the relationship of Sv≥SHmax>Shmin,indicating a dominant normal faulting stress regime within the Chang 7 reservoir of Ordos Basin.Laterally,high stress values are mainly distributed in the northwestern parts of the studied region,while low stress values are found in the southeastern parts.Factors influencing stress distributions are also analyzed.Stress magnitudes within the Chang 7 reservoir show a positive linear relationship with burial depth.A larger value of Young's modulus results in higher stress magnitudes,and the differential horizontal stress becomes higher when the rock Young's modulus grows larger.

Connotation and strategic role of in-situ conversion processing of shale oil underground in the onshore China

In-situ conversion processing (ICP) of shale oil underground at the depth ranging from 300 m to 3 000 m is a physical and chemical process caused by using horizontal drilling and electric heating technology, which converts heavy oil, bitumen and various organic matter into light oil and gas in a large scale, which can be called"underground refinery". ICP has several advantages as in CO2capture, recoverable resource potential and the quality of hydrocarbon output. Based on the geothermal evolution mechanism of organic materials established by Tissot et al., this study reveals that in the nonmarine organic-rich shale sequence, the amount of liquid hydrocarbon maintaining in the shale is as high as 25%in the liquid hydrocarbon window stage (R o less than 1.0%), and the unconverted organic materials (low mature-immature organic materials) in the shale interval can reach 40%to 100%. The conditions of organic-rich shale suitable for underground in-situ conversion of shale oil should be satisfied in the following aspects, TOC higher than 6%, R o ranging between 0.5%and 1%, concentrated thickness of organic-rich shale greater than 15 meters, burial depth less than 3 000 m, covering area bigger than 50 km2, good sealing condition in both up-and down-contacting sequences and water content smaller than 5%, etc. The shale oil resource in China’s onshore region is huge. It is estimated with this paper that the technical recoverable resource reaches 70-90 billion tons of oil and 60-65 trillion cubic meters of gas. The ICP of shale oil underground is believed to be a fairway to find big oil in the source kitchen in the near future. And it is also believed to be a milestone to keep China long-term stability of oil and gas sufficient supply by putting ICP of shale oil underground into real practice in the future.

Kinetic simulation of hydrocarbon generation and its application to in-situ conversion of shale oil

The kinetic parameters of hydrocarbon generation are determined through experimental simulation and mathematical calculation using four typical samples selected from the Cretaceous Nenjiang Formation in the northwest of Songliao Basin,Chang 7 Member of Triassic Yanchang Formation in the southwest of Ordos Basin,Paleogene in the southwest of Qaidam Basin,and Lucaogou Formation of Jimusar Sag in the east of Junggar Basin.The results show that activation energy of hydrocarbon generation of organic matter is closely related to maturity and mainly ranges between 197 kJ/mol and 227 kJ/mol.On this basis,the temperature required for organic matter in shale to convert into oil was calculated.The ideal heating temperature is between 270℃and 300℃,and the conversation rate can reach 90%after 50-300 days of heating at constant temperature.When the temperature rises at a constant rate,the temperature corresponding to the major hydrocarbon generation period ranges from 225 to 350℃at the temperature rise rate of 1-150℃/month.In order to obtain higher economic benefits,it is suggested to adopt higher temperature rise rate(60-150℃/month).The more reliable kinetic parameters obtained can provide a basis for designing more reasonable scheme of in-situ heating conversion.

Heat Dissipation Modeling of <i>In-Situ</i>Conversion Process of Oil Shale

In-situ conversion of process of oil shale has been technically proven as a pilot field project. Gradually heating the reservoir by using subsurface electric heaters converts the oil shale reservoir kerogen into oil, gas and other producible components. This process also enhances the internal energy of the porous media as well as the subsurface fluid. Heat is transmitted in the reservoir within each fluid by different processes i.e. , due to the flow of fluid called advective process, and due to molecular diffusion where dispersive and diffusive processes take place. Heat transfer through conduction and convection mechanisms in the porous media are modeled mathematically and numerically incorporating the advective, dispersive and diffusive processes in the reservoir. The results show the production of oil and gas as a result of conversion of kerogen due to modeled heat dissipation.

Reaction mechanism and kinetics of pressurized pyrolysis of Chinese oil shale in the presence of water

A study of reaction mechanisms and chemical kinetics of pressurized pyrolysis of Chinese Liushuhe oil shale in the presence of water were conducted using an autoclave for simulating and modeling in-situ underground thermal degradation.It was found that the oil shale was first pyrolyzed to form pyrobitumen,shale oil,shale gas and residue,then the pyrobitumen was further pyrolyzed to form more shale oil,shale gas,and residue.It means that there are two consecutive and parallel reactions.With increasing temperature,the pyrobitumen yield,as intermediate,first reached a maximum,then decreased to approximately zero.The kinetics results show that both these reactions are first order.The activation energy of pyrobitumen formation from oil shale is lower than that of shale oil formation from pyrobitumen.

中国石化探区和邻区油页岩原位开采选区评价

中国石化探区油页岩资源丰富,是国家重要的战略储备资源和补充能源。加快油页岩勘探开发对改善中国能源结构和保障国家能源安全具有重要意义。为了实现油页岩规模勘探与效益开发,通过调研梳理国内外成功开展油页岩原位开采现场试验的技术,分析试验区特征、地质和工程适应性、选区选层要求等认为:国外壳牌公司电加热法技术、中国吉林众诚公司的原位压裂化学干馏技术和吉林大学的局部化学反应法原位裂解技术实施了现场先导试验并获得成功,但中国两项技术的成熟度和可行性有待进一步研究论证,且现有的原位开采技术对深部油页岩的适应性均未得到验证。通过开展油页岩原位开采技术特点、地质资源条件、开采工程条件梳理分析,针对约束中国油页岩原位开采的关键因素,结合加热方式确定了4项地质参数、6项工程参数和分级评价界限,并根据约束油页岩原位开采利用的程度确定各参数的权重,建立了油页岩原位开采有利区地质-工程双因素评价模型,优选出15个中国石化探区和邻区油页岩Ⅰ类有利区。对选出的有利区进一步分析其顶底板、断裂、可动水等关键因素的影响,并综合评价优选出4个试验目标区,分别为:鄂尔多斯盆地南缘旬邑区块、博格达山北麓南缘上黄山街含矿区、茂名盆地电白含矿区、抚顺盆地抚顺含矿区。

基于生命周期思想的油页岩原位开采碳排放核算

基于油页岩原位开采的生产实际,指出油页岩行业碳排放核算存在的问题,并将开采过程中钻井、压裂、加热、油气收集与处理、油气运输,以及废水、废弃物、生活垃圾的处置作为碳排放核算边界,确定碳排放源,构建碳排放核算模型,进一步确定排放因子。通过碳排放模型对某油页岩原位开采先导示范基地进行核算,结果表明:加热环节的排放量占比最大,为29.44%;各环节中电力消耗产生的排放量最大。最后提出针对性减排措施。

Enrichment model of continental shale oil in Zhanhua Sag of Jiyang Depression

The quest for enrichment model of continental shale oil in the Zhanhua Sag of the JiyangDepression in the Bohai Bay Basin to provide reference for exploration and development requires acomprehensive approach. Therefore, this study employs rock pyrolysis, Scanning Electron Microscopy(SEM), X-Ray diffraction analysis (XRD), Nuclear Magnetic Resonance (NMR), and other experiments toanalyze the conditions for shale oil enrichment and establish its patterns. The results show that favorablehydrocarbon generation potential and appropriate thermal maturation degree control “in situ enrichment”;while the storage capacity and the mobility of shale oil determine “migration enrichment.” In the process,the TOC governs the oil-generating capacity of shale with medium to large pores and microfractures servingas the main enrichment spaces and migration pathways for shale oil. Based on the deposition model, thestudy area can be divided into five lithofacies stages (I-algal limestone, II-laminated marl, III-laminatedrecrystallized limestone, IV-laminated mudstones, and IV-blocky calcareous mudstones). Integrating thegeochemical parameters into the sedimentary patterns makes it clear that the study area underwent two phasesof hydrocarbon expulsion during the thermal evolution of source rocks (Stage II: 3 060–3 120 m and StageIV: 3 020–3 040 m). However, judging by the observed TOC (2% to 5.6%), thermal maturity (Ro>0.8%),S1 (>2 mg/g) and OSI (>100 mg/g) as well as moderate basin size, climate, and quantity of terrestrial input,the blocky calcareous mudstones (Stage IV) have better oil-prone characteristics and potential to generate asubstantial quantity of hydrocarbons at this stage. More so, with a brittleness index exceeding 60%, it exhibitsfavorable fracturability accounting for the main controlling factors and enrichment patterns of shale oil in thearea. Hence, this study further enriches and develops the theoretical understanding of shale oil enrichment inthe area, provides valuable insights for future exploration of continental shale oil in eastern China and othersimilar basin around the world.

微波辐射对泥页岩孔隙发育的影响——以松辽盆地青山口组一段为例

页岩油被认为是我国油气能源的革命者,其中中低熟页岩油资源潜力巨大。原位加热转化是中低熟页岩油有效开发的潜在技术。本文对松辽盆地青山口组一段富有机质泥页岩开展了常规加热和微波辐射加热实验,并结合场发射扫描电镜、低温氮气吸附实验,系统对比了微波辐射和常规加热页岩时孔隙结构与演化特征。结果表明:有机孔的演化主要经历了开孔→孔隙合并→形成复合孔隙及裂缝三个阶段,加热相同温度时微波辐射能够促进有机质裂解形成有机孔,对微裂缝的发育具有明显的促进作用;随温度增加,孔隙结构参数变化复杂,孔径先增后降,孔体积和比表面积呈增加→降低→增加的特征;随微波辐射加热时间的增加,小于50 nm的孔隙体积大幅减小,中大孔体积明显增加,表明小孔隙逐渐扩张、合并并演变成大孔。微波辐射对页岩孔隙空间改善效果更显著,裂缝更发育,利于油气渗流,但同时发现微波辐射加热的功率过高、时间过长时将会破坏孔隙,不利于改善页岩微观孔隙空间。本项研究对于中低熟页岩油原位加热方式选择及加热过程中微观孔裂隙演化认识有一定的帮助。

中低熟页岩油原位转化开采多相多组分演化的数值模拟研究

中低熟页岩油在我国资源量丰富,具有重要的开采价值。目前应用于中低熟页岩油开采的技术中,原位转化技术具有独特的优势,是未来中低熟页岩油开采重要的发展方向。在前人实验室实验和数值模拟计算的基础上,本文利用自主开发的新型多相流数值模拟器,针对布设的井网中具有代表性的区域建立地质模型,通过精细刻画原位转化过程中井周各相各组分的演化过程,进行定性与定量化的分析。模拟结果表明,原位转化中各组分的演化过程受到组分自身黏性、分解反应的临界温度、井间干扰等因素的影响。临界温度的差异与井间干扰会造成加热井周中组分的分层以及富集区的产生,黏性影响对应组分的生产量。本文基于新的数值模拟方法针对中低熟页岩油原位转化中各组分的演化过程进行定性、定量化研究,以期验证原位转化技术的可行性,并为实际的生产提供参考。

陆相湖盆富有机质泥页岩中方解石脉成因及油气地质意义——以松辽盆地白垩系青山口组为例

基于岩心、岩石薄片观察分析,结合阴极发光、激光拉曼、流体包裹体、LA-ICP-MS原位U-Pb测年等技术手段对松辽盆地白垩系青山口组页岩储层中的方解石脉成因机制及油气地质意义进行研究。结果表明:①在宏观上方解石脉以顺层为主,呈透镜状、“S”形、叠锥状、羽状,在微观上分为向生式块状或柱状晶体结构和背生式纤维状晶体结构脉体。②块状方解石脉中的盐水包裹体均一温度为132.5~145.1℃,原位U-Pb测年绝对年龄为(69.9±5.2)Ma,表明青山口组烃源岩中成熟期和常规油的形成时期为晚白垩世明水组沉积期。纤维状方解石脉中的盐水包裹体均一温度为141.2~157.4℃,对应于烃源岩晚成熟期,U-Pb测年绝对年龄为(44.7±6.9)Ma,指示青山口组烃源岩的中高成熟期和古龙油页岩的形成时间为古近纪依安组沉积期。③向生式块状或柱状晶体结构方解石脉的形成与成岩成烃作用有关,脉体的形成经过了裂缝的开启、成脉流体充填和脉体生长3个阶段,构造挤压活动和流体超压是裂缝形成的诱导因素,成脉流体以短距离的扩散流为主,是一种有竞争的结晶生长模式。背生式纤维状方解石脉主要是在一种无竞争生长环境下由结晶力驱动形成的。研究认为,研究区青山口组富有机质泥页岩中的方解石脉对于松辽盆地构造活动、流体超压、泥页岩生排烃及成岩-成藏年龄具有一定指示意义。

页岩油集输过程关键子系统风险评价及安全防控

为提高页岩油集输过程的安全性,首先以过热蒸汽注入油页岩原位转化技术下的页岩油集输过程为评价对象,分析页岩油集输过程中的危险源,将整个集输过程分为3个子系统,利用危险性与可操作性分析(HAZOP)法定性分析各子系统的风险,并根据定性分析结果,利用保护层分析法(LOPA)和火灾爆炸指数法(F&EI)计算各子系统发生火灾爆炸事故的概率与危险等级;然后划分页岩油集输过程的节点,对含有硫化氢的油气泄漏事故与净化后的油气泄漏事故分别建立蝴蝶结模型,并依据风险评价结果,制定有效的安全防控措施和风险管理体系。结果表明:油气集输过程可能引发事故的子系统有蒸汽发生系统、冷却分离系统、氨法脱硫系统与冷却分离系统,其中,蒸汽发生系统泄漏不会造成火灾爆炸事故,其余子系统的火灾爆炸风险程度由重到轻依次为:氨法脱硫系统、冷却分离系统、提气脱硫系统。

基于力学时变性的页岩油藏四维地应力演化规律研究

裂缝对页岩岩石力学性质影响突出,准确表征含裂缝页岩的岩石力学性质变化是实现页岩油藏压裂-投产过程中四维地应力场精准刻画的重要基础。已有四维地应力研究通常认为应力变化主要源于孔隙压力改变,未考虑岩石力学性质变化对四维地应力的影响。利用在线CT实验,明晰了孔隙压力与页岩孔缝体积的关系,依据应变能理论,推导了裂缝体积与页岩泊松比、弹性模量的理论关系,建立了孔隙压力与泊松比、弹性模量的时变理论模型。结果表明,层理缝开启是页岩岩石力学参数具有时变性的主要原因,孔隙压力越大,裂缝开启条数越多,裂缝空间呈指数型增长。随裂缝体积增加,页岩泊松比快速增加、杨氏模量快速减小,页岩强度大幅降低。以济阳坳陷页岩为例开展分析,裂缝体积占比提高至1%时,杨氏模量由37.5GPa下降至15.06GPa,泊松比由0.22上升至0.35。依托数值模拟方法对比分析岩石力学参数时变性对四维地应力演化的影响,考虑岩石力学时变性特征的四维地应力模拟能够更好地表征页岩压裂-投产过程中的应力大小演化与方向偏转的规律,与实际油藏压裂-投产过程中的四维地应力演化规律更加吻合,模拟结果更加可靠。研究成果能够为页岩油立体井组合理部署、优化设计、风险预警等提供理论支撑。

油页岩原位开采物理模拟试验研究现状及展望

合理高效地原位开采油页岩资源对缓解常规油气资源枯竭具有重要的战略意义。鉴于目前油页岩现场原位开采的不确定性和工艺复杂性,物理模拟试验成为了研究油页岩原位开采热解及传热机制的有效手段。通过查阅大量文献发现:油页岩原位开采模拟试验装置由毫米(颗粒)尺寸向厘米、米级(现场)大型尺寸迭代升级,各种大型多功能三轴智能化试验系统已研制成功。试验研究了温度、应力和共热物质对油页岩热解的影响,分析了油气产物、孔缝结构和渗透率演化特征,形成了具有我国特色的油页岩原位开采研究体系。针对新形势下油页岩原位开采研究存在的不足,对未来的研究方向提出建议和展望,旨在完善油页岩原位开采研究体系,早日实现油页岩大规模原位开采。

预热气体对油页岩自生热原位转化效果的影响

地下原位转化是油页岩工业化开发的必然趋势,自生热法是实现油页岩地下原位转化的一种复合高效加热方法。为探究预热阶段不同高温载气对油页岩自生热原位转化效果的影响,以我国吉林扶余地区油页岩为例,分别在预热阶段注入氮气、空气、蒸汽、二氧化碳4种高温气体进行数值模拟分析,对比最终油气产量和能量回收率的差异。以预热阶段注高温氮气组作为对照组,结果表明注高温空气、蒸汽和二氧化碳完成开采所需时间分别降低22%、39%、12%,最大能量回收率分别提高55%、86%、23%,总油收量分别降低5%、提高18%和降低11%。从开采完成时间、能量回收率及总油收量角度来看,注蒸汽预热效果最佳。因此,综合对比可得,注蒸汽预热的自生热开采方法可有效增大油收量、降低开采所需时间、提高能量利用率。

页岩油储层补能前后四维地应力模拟及加密井复杂裂缝扩展规律研究

针对安83井区长7含油层水平井区采出程度低、剩余油丰富的问题,结合考虑页岩油储层地质力学参数、天然裂缝等的非均质性和各向异性,建立一套地应力场与渗流场耦合机理模拟方法,将传统油藏渗流模拟与地质力学模拟相结合,并通过压裂施工参数、现场试井数据、微地震监测数据等,开展了储层补能前后四维地应力模拟及加密井复杂裂缝扩展规律研究。研究结果表明,该区储层杨氏模量高、泊松比低,易发生破裂;大规模压裂可以形成复杂裂缝,基本上为长250 m、宽80 m的多簇式裂缝条带;水介质补能能够起到均匀补能效果,效果比气介质好;老井补能至原始压力的80%时,压裂裂缝改造充分,裂缝扩展均衡,老井单井补能液量5000 m^(3)最优;300 m加密井补能至原始地层压力的120%时,压裂后改造较充分,单井补能液量25000m^(3)左右最优。该模拟分析方法对同类型油藏地应力模拟及裂缝扩展规律研究有重要指导意义。

石油压裂的电力驱动与储能系统的应用

压裂技术是针对石油、天然气等储存在地下的能源而开发出来的提高产量的一种方法。而由变频驱动的电驱压裂是页岩能源开采设备的必然发展趋势,具备排量精准控制、功率密度大等优势。在部分现场不具备电网的条件下,燃机加储能在页岩油气的压裂中也应运而生。由变频驱动的电驱压裂及提供能源储备的储能为石油行业的降本增效、节能减排发挥重要作用。

基于原位转化/改质技术的陆相页岩选区评价——以鄂尔多斯盆地三叠系延长组7段页岩为例

与依靠水平井体积压裂技术的页岩气、致密油开发相比,原位转化/改质技术更适合规模效益开发中国陆相大面积分布、成熟度介于0.5%~1.0%、总有机碳质量分数大于6%的页岩层系液态烃资源.本研究基于原位转化/改质技术具有不受地质条件限制、地下转化轻质油、高采出程度、较低污染等技术优势的特点,综合考虑鄂尔多斯盆地延长组7段页岩厚度、页岩有机质丰度、热演化程度和现今埋深等地质参数,评价优选试验有利区主要分布在盆地东南部,其中埋深小于1 500 m的分布面积大于6 000 km^2.页岩选区评价结果表明,鄂尔多斯盆地陆相页岩是原位转化/改质技术工业试验的有利页岩分布区.

中国油页岩原位开采可行性初探

中国油页岩资源量为11 602×108t,其中埋藏深度在500～1 500 m的油页岩资源量为6 813×108t,原位开采技术是开发该部分资源的有效手段。中国油页岩原位开采技术处于实验阶段,通过对油页岩热分解、热破裂规律、渗透变化规律等方面的研究,初步探索了油页岩原位开采的可行性。油页岩热分解过程可以分为3个阶段:干燥脱水、热解生油、无机矿物质的分解。在这3个阶段中,由于油页岩内部物理化学反应的程度不同,导致孔隙和裂缝发生了不同程度的变化,变化最大的是热解生油阶段。利用非稳态数学模型研究了油页岩电加热原位开采的温度场分布,表明加热5 a后可以对页岩油进行开采,产油时间至少可以维持2 a。

利用微波加热开采地下油页岩的技术

对目前国内外油页岩原位开采技术研究进行的分析表明,油页岩具有导热性差的特点。为了解决传统的热传导开采方法效率低、成本高的问题,提出了一种微波加热开采油页岩的新型技术。利用微波加热方式,电磁能直接作用于介质分子而转换成热能,其透射性能使物料内外介质同时受热,不需要热传导。在方案实施过程中,在油页岩层中钻羽状井并填入吸波介质,可大大改善油页岩的吸波能力,可以以较快的速度使页岩油的升温,并逐渐地将干酪根裂解转化为页岩油气。页岩油气会通过加热产生的裂缝运移到生产井,并被抽排到地面。