2023年度全球油气开发现状、形势及启示

通过对2023年全球油气田分布及生产概况、剩余可采储量分布及变化特征、不同区域及国家间油气生产差异对比、未建产与待建产油气田开发潜力4个方面的分析,梳理了全球油气开发现状与特征,总结了全球油气的开发形势。2023年全球油气上游生产版图不断扩大,在产油气田数显著增长;油气可采储量同比提升,新项目发现与储量复算贡献突出;油气产量持续增长,新项目投产和产能建设项目贡献显著;未建产/待建产油气田可采储量丰富,集中于陆上常规大油田与低经济性海域气田。以疫情叠加俄乌冲突重塑全球油气产区、地缘政治危机、油气勘探开发领域资本支出结构、油气伴生资源超前布局等视角为切入点深入分析,为后疫情时代及能源转型趋势下中国石油公司聚焦主营业务领域和明确战略发展方向提出4点启示与建议:全球油气格局深刻调整,把握发展趋势聚焦主营业务;上游业务开发潜力强劲,涉足新兴领域助力接续发展;致密/页岩油气前景可期,探索保障国家能源安全新路;战新产业实现前沿突破,建立综合能源协同保供体系。

2022年度全球油气开发现状、形势及启示

通过对2022年全球油气田分布及生产概况、剩余可采储量分布及变化特征、不同区域及国家间油气生产差异、未建产与待建产油气田开发潜力4个方面的分析,梳理了全球油气开发现状与特征,分析研究了全球油气的开发形势。2022年全球油气田分布广泛,上游生产活动持续恢复,油气储量同比微降但海域油气储量增幅明显。油气产量持续增长,重点资源国油气增产贡献大。未建产/待建产油气田储量丰富,预测伴随经济性改善开发潜力将逐步释放。通过全球油气开发领域资源接续、地缘政治风险、“一带一路”合作潜力、非常规油气技术升级分析,提出新形势下中国石油公司聚焦核心业务领域和明确战略发展方向4点启示与建议:发挥石油公司比较优势,借鉴合作经验立足陆上常规油气开发;推动开发调整先导试验,深化“一带一路”油气提高采收率合作;提升海域油气作业能力,实现从小股东跟随到联合再到独立作业的突破;探索页岩油气开发途径,降低油气对外依存度。

海外油气田开发特点、模式与对策

基于中国石油公司20多年来海外油气田开发的经验,全面总结了海外油气田开发的特点、开发理念、开发模式及开发方案设计策略。海外油气田开发具有项目资源的非己性、合同模式的多样性、合作方式的复杂性等10大特点。基于以追求有限合同期内产量和效益最大化为目标的海外油气田开发理念,建立了早期优先利用天然能量开发、规模建产、快速上产、高速开采、快速回收的海外油气田开发模式。确定了适应不同合同类型的海外油气田开发方案设计策略,对于矿税制合同,优先开发富集且技术难度小的资源,依据合同规定的矿费变化确定早期投资进度、上产速度、开发工作量和产量;对于产品分成合同,高速开发,稀井高产,加快投资回收;对于技术服务合同,根据投资回报率确定方案的合理产量目标和工作量,确保高峰期产量和稳产期达到合同要求。

2021年全球油气开发现状、形势及启示

通过对2021年全球油气田分布及部分油气田不在产原因、剩余可采储量分布特征及同比变化、油气产量分布特征及同比变化、未建产与待建产油气田开发潜力4个方面的分析,梳理了全球油气开发现状与特征,总结全球油气的开发形势,提出对国际油气合作的启示。2021年全球油气田分布广泛,不在产油气田数量较多;油气储量略有下滑,非常规油气储量下降多;油气产量持续增长,重点资源国产量同比增幅大;未建产/待建产油气田储量丰富,未来开发潜力较大。结合对全球油气地缘政治、油气行业发展趋势、油气投资强度、热点领域的追踪和研判,总结了2021年全球油气的开发形势,在此基础上,针对国际油气合作和发展战略提出4点启示与建议:高度重视海洋弃置义务,确保海域油气实现高质量长期效益发展;坚持危地不往、乱地不去,提升油气资产集中度,建立稳定保供基地;立足天然气多情景需求,实现一体化协同向全业务链发展的转变;加大优质规模资产获取,注重不同阶段项目持股比例的持续优化。

封闭边界压裂水平井非稳态产能评价新模型

在压裂水平井垂直裂缝等效井径模型的基础上,应用镜像反演理论及压降叠加原理,建立了矩形封闭地层压裂水平井产能分析方法;利用数值求解,得到了压裂水平井各条裂缝的产量变化规律,并分析了压裂水平井产能影响因素。结果表明:压裂水平井初期产能高,产量递减快,之后产量趋于平缓;生产初期,各条裂缝产量相差不大,压裂水平井产量随裂缝条数的增加而增加,而各条裂缝间的产量差距随生产时间延长逐渐增大,表现为边部裂缝产量高,中间裂缝产量低;压裂水平井产能受裂缝条数、无因次裂缝导流能力、裂缝缝长的综合影响,其中裂缝条数和无因次裂缝导流能力对压裂水平井产能影响较大,裂缝缝长对压裂水平井产能影响相对较小。

基于储层动用程度的块状砂体流动单元划分方法及应用研究:以哈萨克斯坦Akshabulak油田为例

以南图尔盖盆地Akshabulak油田J-Ⅲ层块状砂体为例,利用油田投产初期生产工作制度相近井的产液剖面资料和单井日产油量划分出“好”“较好”“中等”“差”4类储层动用程度类型。以储层动用程度类型为判别函数,利用岩心分析资料选出与储层动用程度类型响应较好的7类地质参数。以7类地质参数为变量,以测井解释数据为基础,运用神经网络聚类技术将储层划分为“高”“较高”“中等”“低”4类不同级别的流动单元。统计结果表明,4类储层动用程度类型与4种级别流动单元的静态地质参数和动态开发指标界限具有较好的对应性。研究结果表明流动单元的组合样式决定了储层的垂向和平面动用程度:垂向上,流动单元发育种类越多,水体会优先流向高级别流动单元,这导致油藏垂向水驱动用程度不均匀;平面上,高级别流动单元较发育的区域,水体会优先波及,这导致油藏平面水驱前缘推进速度有明显差异。在此基础上提出垂向上高级别流动单元实施调剖堵水、平面上天然水驱协同人工注水开发的开发技术策略,实现了稳产高效开发。

滨里海盆地东缘石炭系碳酸盐岩储集层孔喉结构特征及对孔渗关系的影响

滨里海盆地东缘石炭系碳酸盐岩储集层经受了复杂的沉积、成岩和构造作用,发育孔、洞、缝多种储集空间且组合方式多样,孔喉结构复杂,导致储集层孔渗关系复杂,严重制约储集层分类评价和高效开发。综合岩心、薄片、扫描电镜、高压压汞、常规物性分析及各类测试资料,对孔洞缝型、孔洞型、裂缝-孔隙型和孔隙型储集层的孔喉结构特征、主控因素及对孔渗关系的影响展开系统研究,取得了3项进展:①建立了一套适用于滨里海盆地东缘石炭系复杂碳酸盐岩的孔喉结构分类和描述方法,划分出多模态宽广型、双模态宽广型、单模态集中型和双模态高低不对称型4种孔喉结构类型,构建孔喉结构判别指数实现对孔喉结构类型的定量判别;②明确了孔隙型储集层的微观非均质性最强,4种孔喉结构均发育,其次是裂缝-孔隙型和孔洞缝型储集层,孔洞型储集层微观非均质性相对较弱,阐明了沉积、成岩和构造叠加改造作用形成的储集空间组合类型是孔喉结构差异的主控因素;③揭示了多种孔喉结构共同发育是导致各类储集层孔渗相关性差的关键因素,细分孔喉结构类型建立各类储集层孔渗关系是提高渗透率计算准确度的有效手段。上述研究成果加深了对复杂碳酸盐岩储集层孔喉结构的认识,对碳酸盐岩储集层分类评价、准确建立孔渗关系和高效开发具有较好的指导意义。

稠油油藏反九点井网非活塞水驱平面波及系数计算方法

为更准确迅速地计算稠油油藏反九点井网水驱波及系数,更有效地进行井网评价,根据正方形反九点井网的对称性,将其划分为2个对称的渗流单元,从非达西渗流出发,运用流线积分法推导了既考虑启动压力梯度又考虑油水黏度比的普通稠油油藏正方形反九点井网非活塞式水驱平面波及系数计算公式。利用该公式分析了启动压力梯度和注采参数等因素对普通稠油油藏正方形反九点井网水驱平面波及系数的影响,进而对哈萨克斯坦NB常规稠油油藏现有井网进行了评价,并提出井网调整方法。研究结果表明:减小井距或增大注采压差能有效增大常规稠油油藏平面波及系数,油藏的启动压力梯度越大,注采压差和井距大小对平面波及系数影响就越明显。

油砂多分支水平井SAGD开发规律数值模拟研究及现场开发效果评价

储层非均质性对应用蒸汽辅助重力泄油技术(SAGD)的井对开发效果影响很大,在复杂的储层条件下难以确保蒸汽腔的均匀发育,单井对开发效果受限。针对加拿大麦凯河区块油砂项目SAGD开发过程中存在的储层非均质性强、地质条件复杂、泥披层遮挡导致的蒸汽腔发育受阻、发育不均匀,从而造成单井峰值产量降低、采收率降低的问题,提出了不同井型上倾多分支井技术,采用数值模拟和现场动态分析方法,探索了蒸汽腔穿过泥披层发育、加热后冷凝油穿过泥披层遮挡进入生产井井筒的方法,准确认识了不同井型多分支井的蒸汽腔发育情况并评价了其开发效果。通过构建机理模型,设计了4种注汽井与生产井组合方案,采用现场实际操作参数进行模拟,对生产动态、剩余油分布、蒸汽腔发育、水平段动用等情况进行了分析,总结出多分支水平井在复杂储层条件下的生产规律;通过对现场投产井开展生产动态分析,评价了多分支井SAGD开发效果,对比了不同井型开发效果差异。结果显示:采用多分支井设计可明显增加有效进尺,促成了注汽和泄油的优势通道,提高井对注汽能力,增大蒸汽腔的波及体积,井对峰值日产油水平提高,在一定程度上解决了泥披层的遮挡问题;在实际现场生产中,多分支生产井可提高生产井水平段动用程度,提高单井开发效果,但在一定程度上会加剧井间干扰与调控难度,导致储层下部剩余油增加。

稠油油藏水平井过热蒸汽吞吐储层适应性评价

过热蒸汽吞吐是目前开采稠油油藏的一种有效技术。由于过热蒸汽与普通湿蒸汽存在明显差异,基于普通湿蒸汽而建立的稠油蒸汽吞吐储层筛选标准并不完全适用于过热蒸汽吞吐。针对这一问题,以哈萨克斯坦K油藏水平井过热蒸汽吞吐先导试验区为研究对象,根据经济收支平衡原理,建立了水平井过热蒸汽吞吐的经济极限指标,并在此基础上以单井极限收益为依据,利用数值模拟方法确定了水平井过热蒸汽吞吐的地质及流体参数经济界限值,最终得到了水平井过热蒸汽吞吐的储层筛选标准。该储层筛选标准的建立为稠油油藏实施水平井过热蒸汽吞吐经济高效开发提供了理论指导。

考虑砾石充填防砂过渡带影响的水平井产能预测

为研究砾石充填防砂过渡带对水平井产能的影响,将井筒管流与油藏渗流相耦合,在描述过渡带渗透率及半径等相关物性的基础上,建立考虑砾石充填防砂过渡带影响的水平井产能预测模型,并对产能影响因素进行分析。研究表明:考虑过渡带影响的水平井产能计算结果与油井实际产能较接近,不考虑过渡带影响的水平井产能预测值偏大;井筒内压力由趾端向跟端不断下降,而井筒入流量不断上升,二者均表现为近趾端处变化幅度小,近跟端处变化幅度大;水平井产能随过渡带渗透率的增大而增大,随过渡带半径的增加而减小。

Geochemical characteristics and genetic model of dolomite reservoirs in the eastern margin of the Pre-Caspian Basin

The widespread Carboniferous KT-I dolomite in the eastern margin of the Pre-Caspian Basin is an important hydrocarbon reservoir. The dolomite lithology is dominated by crystalline dolomite. The δ18O values range from -6.71‰ to 2.45‰, and average 0.063‰, obviously larger than -2.5‰, indicating low-temperature dolomite of evaporation origin. Stable strontium isotope ratios （87Sr/86Sr） range from 0.70829 to 0.70875 and average 0.708365, very consistent with 87Sr/86Sr ratios in Carboniferous seawater. Chemical analysis of Ca and Mg elements shows that the dolomite has 9.1 mole% excess Ca or even higher before stabilization. The degree of order of dolomite is medium–slightly poor, varying in a range of 0.336-0.504 and averaging 0.417. It suggests that the dolomite formed under near-surface conditions. There are two models for the origin of the Carboniferous KT-I dolomite reservoir. These are 1） the evaporation concentration – weathering crust model and 2） the shoal facies – seepage reflux model. The former is mainly developed in restricted platforms – evaporate platforms of restricted marine deposition environments with a representation of dolomite associated with gypsum and mudstone. The latter mainly formed in platform edge shoals and intra-platform shoals and is controlled by dolomitization due to high salinity sea water influx from adjacent restricted sea or evaporate platform.

Characteristics of strike-slip inversion structures of the Karatau fault and their petroleum geological significances in the South Turgay Basin,Kazakhstan

The Karatau fault is one of the important strike-slip faults in central Asia,and the South Turgay Basin is located towards its northern end.Detailed seismic interpretation indicated that the strikeslip tectonism of the Karatau fault weakened gradually from west to east in the South Turgay Basin.Typical flower structures developed on the section,and strike-slip faults showed an echelon pattern on planar view.The Karatau strike-slip fault affected the South Turgay Basin in two periods：（1） The South Turgay strike-slip pull-apart rift basin formed as a result of regional extensive stress in the Early-Middle Jurassic,characterized by the juxtaposition of horsts and grabens.The formation of horsts provided favorable reservoir spaces for later hydrocarbon accumulation,and different filling stages of grabens controlled different reservoir-forming factors in grabens.（2） Two stages of tectonic inversion occurred in the Late Jurassic and Late Cretaceous and played a crucial role in the final shape of the structure in the South Turgay Basin.The oil and gas migrated to form reservoirs and mainly concentrated in the horsts,graben slopes and in both sides of the strike-slip fault zone.In the case of the degree of accumulation of petroleum,the factor explaining why horsts are better than grabens is the strike-slip pull-apart of the South Turgay Basin,and the structure inversion of the South Turgay Basin explains why the west graben is better than the east one.Overall,the Karatau strike-slip fault played a very important role in the formation of the South Turgay Basin and its hydrocarbon accumulations.

Status, trends and enlightenment of global oil and gas development in 2021

By analyzing the distribution of global oil and gas fields and the reasons why some oil and gas fields are not in production, the distribution characteristics of oil and gas remaining recoverable reserves and their year-on-year changes, the distribution characteristics of oil and gas production and their year-on-year changes, and the development potential of oil and gas to be tapped in 2021, this paper sorts out systematically the current status and characteristics of global oil and gas development, summaries the major trends of global oil and gas development, puts forward enlightenment for international oil and gas cooperation. In 2021, oil and gas fields were widely distributed, the number of non-producing oil and gas fields was large;the whole oil and gas remaining recoverable reserves declined slightly, unconventional oil and gas remaining recoverable reserves dropped significantly;the overall oil and gas production continuously increased, the outputs of key resource-host countries kept year-on-year growth;undeveloped oilfields had abundant reserves and great development potential. Combined with global oil and gas geopolitics, oil and gas industry development trends, oil and gas investment intensity, and the tracking and judgment of hotspot fields, the major trends of global oil and gas development in 2021 are summarized. On this basis, the four aspects of enlightenment and suggestions for international oil and gas cooperation and development strategies are put forward: attach great importance to the obligation of marine abandonment to ensure high-quality and long-term benefit development of offshore oil and gas;adhere to the principle of not going to dangerous and chaotic places, strengthen the concentration of oil and gas assets, and establish multi stable supply bases;based on the multi-scenario demand of natural gas, realize the transformation from integrated collaboration to full oil and gas industry chain development;increase the acquisition of high-quality large-scale assets, and pay attention to the continuous optimization of the shareholding ratio of projects at different stages.

Pore-throat structure characteristics and its impact on the porosity and permeability relationship of Carboniferous carbonate reservoirs in eastern edge of Pre-Caspian Basin

Carboniferous carbonate reservoirs at the eastern edge of the Pre-Caspian Basin have undergone complex sedimentation,diagenesis and tectonism processes,and developed various reservoir space types of pores,cavities and fractures with complicated combination patterns which create intricate pore-throats structure.The complex pore-throat structure leads to the complex porosity-permeability relationship,bringing great challenges for classification and evaluation of reservoirs and efficient development.Based on the comprehensive analysis on cores,thin sections,SEM,mercury intrusion,routine core analysis and various tests,this paper systematically investigated the features and main controlling factors of pore-throats structure and its impact on the porosity-permeability relationship of the four reservoir types which were pore-cavity-fracture,pore-cavity,pore-fracture and pore,and three progresses are made.(1)A set of classification and descriptive approach for pore-throat structure of Carboniferous carbonate reservoirs applied to the eastern edge of the Pre-Caspian Basin was established.Four types of pore-throat structures were developed which were wide multimodal mode,wide bimodal mode,centralized unimodal mode and asymmetry bimodal mode,respectively.The discriminant index of pore-throat structure was proposed,realizing the quantitative characterization of pore-throat structure types.(2)The microscopic heterogeneity of pore reservoir was the strongest and four types of pore-throat structures were all developed.The pore-fracture and pore-cavity-fracture reservoirs took the second place,and the microscopic heterogeneity of pore-cavity reservoir was the weakest.It was revealed that the main controlling factor of pore-throat structure was the combination patterns of reservoir space types formed by sedimentation,diagenesis and tectonism.(3)It was revealed that the development of various pore-throat structure types was the important factor affecting poroperm relationship of reservoirs.The calculation accuracy of permeability of reservoirs can be improved remarkably by subdividing the pore-throat structure types.This study deepens the understanding of pore-throat structure of complicated carbonate reservoirs,and is conducive to classification and evaluation,establishment of precise porosity-permeability relationship and highly efficient development of carbonate reservoirs.

An Evaluation of Phase Behaviors of the Oil-Gas-Water System in the Displacement of Crude Oil with CO_(2)

CO_(2)dissolution into an aqueous phase and water evaporation into a gaseous phase takes place during CO_(2)injection into an oil reservoir.This study aims to evaluate the phase behaviors of the oil-gas-water system in the displacement of crude oil by CO_(2).The composition of the JL oilfield in the northeast of China is taken as an example.The flash calculation of the oil-gas-water system was performed,based on the method presented by Li and Nghiem.The research results show that CO_(2)dissolution in the aqueous phase declines as the NaCl concentration in formation water rises.CO_(2)injection is beneficial for the evaporation of formation water.The NaCl concentration in formation water has little effect on water evaporation and dissolved-gas escape.When the injection-gas mole fraction of CO_(2)is 0.5,CO_(2)injection can reverse the phase behavior of the petroleum mixture and the oil-gas system is converted to a pure gas-condensate system.For CO_(2)injection,water vapor has little effect on the miscibility of multiple contacts,but can reduce the miscibility of the first contact.

Global oil and gas development in 2022:Situation,trends and enlightenment

Through analysis of four aspects,including the distribution and production of global oil and gas fields,the distribution and changes of remaining recoverable reserves,the differences in oil and gas production between regions/countries,and the development potential of oil and gas fields with production capacity not built and to be built,this paper presents the situation and trends of global oil and gas development in 2022.It is found that,in 2022,oil and gas fields are widely distributed worldwide,and upstream production activities continue to recover;the oil and gas reserves decrease slightly year on year,and the oil and gas reserves in sea areas increase significantly;the oil and gas production increases continuously,and the key resource countries make a significant contribution in oil and gas production growth;the oil and gas fields with production capacity not built and to be built hold abundant reserves,and their development potential will be gradually released with the economic benefits increase.Further analysis is conducted from the perspectives of global oil and gas resources continuity,geopolitical risks,potential of international cooperation,and upgrade of unconventional oil and gas technology.Finally,in view of core business domains and strategies under the new situation,the Chinese oil companies are recommended to:(1)keep a foothold in onshore conventional oil and gas development by virtue of their comparative advantages and learning from other’s experience in cooperation;(2)carry out pilot tests on development adjustment,and deepen the international cooperation in enhanced oil/gas recovery;(3)improve the oil and gas operation capabilities in sea areas to transform from follower as minority shareholder to joint venture and then to independent operations;and(4)seek appropriate ways for shale oil/gas development to reduce the dependence on foreign oil and gas.

Temperature distribution of fluids in a two-section two-phase closed thermosyphon wellbore

Compared with a conventional single section two-phase closed thermosyphon （TPCT） wellbore, a two-section TPCT wellbore has better heat transfer performance, which may improve the temperature distribution of fluid in wellbores, increase the temperature of fluid in wellheads and even more effectively reduce the failure rate of conventional TPCT wellbores. Heat transfer performance of two-section TPCT wellbores is affected by working medium, combination mode and oil flow rate. Different working media are introduced into the upper and lower TPCTs, which may achieve a better match between the working medium and the temperature field in the wellbores. Interdependence exists between the combination mode and the flow rate of the oil, which affects the heat transfer performance of a two-section TPCT wellbore. The experimental results show that a two-section TPCT wellbore, with equal upper and lower TPCTs respectively filled with Freon and methanol, has the best heat transfer performance when the oil flow rate is 200 L/h.

Development characteristics, models and strategies for overseas oil and gas fields

Based on about 20 years of accumulated experience and knowledge of oil and gas field development in overseas countries and regions for China's oil companies, the development features, ideas, models and plan designing strategies of overseas oil and gas fields were comprehensively summarized. Overseas oil and gas field development has ten major features, such as non-identity project resource, diversity of contract type, complexity of cooperation model, and so on. The overseas oil and gas field development aims at the maximization of production and benefit during the limited contract period, so the overseas oil and gas field development models are established as giving priority to production by natural energy, building large-scale production capacity, putting into production as soon as possible, realizing high oil production recovery rate, and achieving rapid payback period of investment. According to the overseas contract mode, a set of strategies for overseas oil and gas field development plans were made. For tax systems contracts, the strategy is to adopt the mode of "first fat and then thinner, easier in the first and then harder", that is, early investment pace, production increase rate, development workload and production were decided by the change of tax stipulated in the contract. For production share contracts, the strategy is to give priority to high production with a few wells at a high production recovery rate to increase the cost-oil and shorten the period of payback. For technical service contracts, the strategy is that the optimal production target and workload of the project were determined by the return on investment, so as to ensure that the peak production and stable production periods meet the contract requirements.