Petroleum exploration and production in Brazil:From onshore to ultra-deepwaters

The Santos Basin in Brazil has witnessed significant oil and gas discoveries in deepwater pre-salt since the 21^(st)century.Currently,the waters in eastern Brazil stand out as a hot area of deepwater exploration and production worldwide.Based on a review of the petroleum exploration and production history in Brazil,the challenges,researches and practices,strategic transformation,significant breakthroughs,and key theories and technologies for exploration from onshore to offshore and from shallow waters to deep-ultra-deep waters and then to pre-salt strata are systematically elaborated.Within 15 years since its establishment in 1953,Petrobras explored onshore Paleozoic cratonic and marginal rift basins,and obtained some small to medium petroleum discoveries in fault-block traps.In the 1970s,Petrobras developed seismic exploration technologies and several hydrocarbon accumulation models,for example,turbidite sandstones,allowing important discoveries in shallow waters,e.g.the Namorado Field and Enchova fields.Guided by these models/technologies,significant discoveries,e.g.the Marlim and Roncador fields,were made in deepwater post-salt in the Campos Basin.In the early 21^(st)century,the advancements in theories and technologies for pre-salt petroleum system,carbonate reservoirs,hydrocarbon accumulation and nuclear magnetic resonance(NMR)logging stimulated a succession of valuable discoveries in the Lower Cretaceous lacustrine carbonates in the Santos Basin,including the world-class ultra-deepwater super giant fields such as Tupi(Lula),Mero and Buzios.Petroleum development in complex deep water environments is extremely challenging.By establishing the Technological Capacitation Program in Deep Waters(PROCAP),Petrobras developed and implemented key technologies including managed pressure drilling(MPD)with narrow pressure window,pressurized mud cap drilling(PMCD),multi-stage intelligent completion,development with Floating Production Storage and Offloading units(FPSO),and flow assurance,which remarkably improved the drilling,completion,field development and transportation efficiency and safety.Additionally,under the limited FPSO capacity,Petrobras promoted the world-largest CCUS-EOR project,which contributed effectively to the reduction of greenhouse gas emissions and the enhancement of oil recovery.Development and application of these technologies provide valuable reference for deep and ultra-deepwater petroleum exploration and production worldwide.The petroleum exploration in Brazil will consistently focus on ultra-deep water pre-salt carbonates and post-salt turbidites,and seek new opportunities in Paleozoic gas.Technical innovation and strategic cooperation will be held to promote the sustainable development of Brazil's oil and gas industry.

Analysis of the world deepwater oil and gas exploration situation

The global trends in deepwater oil and gas exploration,characteristics of deepwater oil and gas discovery,and layout of deepwater oil and gas exploration business by seven major international oil companies are systematically analyzed using commercial databases(e.g.S&P Global and Rystad)and public information of oil companies.The deepwater area is currently the most important domain for global oil and gas exploration and discovery,with the most discoveries and reserves in passive continental margin basins.The deepwater discoveries have the greatest contribution to the total newly discovered oil and gas reserves in the sea areas,with an increasing number of lithological reservoirs discovered,and oil and gas discoveries mainly distributed in the Mesozoic–Cenozoic.The seven major international oil companies are widely active in various aspects of deepwater oil and gas exploration and development,and play a leading role.Based on years of theoretical understanding of global oil and gas geology and resource evaluation,it is proposed that favorable deepwater exploration areas in the future will mainly focus on three major areas:the Atlantic coast,the Indian Ocean periphery,and the Arctic Ocean periphery.Six suggestions are put forward for expanding overseas deepwater oil and gas exploration business:first,expand the sources for obtaining multi-user seismic data and improve the scientific selection of deepwater exploration areas;second,increase efforts to obtain deepwater exploration projects in key areas;third,adopt various methods to access into/exit from resource licenses flexibly;fourth,acquire licenses with large equity and operate in“dual-exploration”model;fifth,strengthen cooperation with leading international oil companies in deepwater technology;and sixth,improve business operation capabilities and gradually transform from“non-operators”to“operators”.

Evolution of deepwater sedimentary environments and its implication for hydrocarbon exploration in Qiongdongnan Basin, northwestern South China Sea

Over the past several years, a number of hydrocarbon reservoirs have been discovered in the deepwater area of Qiongdongnan Basin, northwestern South China Sea. These oil/gas fields demonstrate that the evolution of the deepwater sedimentary environment are controlling the formation and distribution of large-scale clastic reservoirs. Integration between seismic and borehole data were necessary to best clarify the distribution and quality of these deepwater reservoirs. Geochemical and paleobiological evidence from discrete samples was also applied to document specific information regarding the sedimentary environment. Results show that the Qiongdongnan Basin has existed as a thriving marine environment since Oligocene, when several rifting depressions developed throughout the entire Qiongdongnan Basin. Triggered by the faults activities, several distinct provenances supplied the coarse sediments, transporting and depositing them in deep parts of the rifting depressions. A fan delta system then formed nearby the source in the deeper area of these rifting depressions. The sedimentary environment of Qiongdongnan gradiationally became deepwater since early Miocene. Consequently, abundances of sediments were transported from Hainan Island and Southern Uplift, and then sunk into the basin center. The submarine fans revealed by many boreholes in this area verified them as good reservoir. Because the area reached its lowest sea level at late Miocene and the Southern Uplift subsidenced under sea level, not providing any sediment, so that the carbonate mesa and biorhythms characteristic of this area also developed during this period. In the west part of Qiongdongnan Basin, sediments transported from Vietnam increased in response to the Tibetan Uplift. Consequently, a central canyon developed along the center of Qiongdongnan Basin, which has been confirmed by several boreholes as a favorable hydrocarbon reservoir. The clarification of the deepwater sedimentary environment’s evolution is potentially highly beneficial to future hydrocarbon exploration in the deepwater area of Qiongdongnan Basin.

Hydrocarbon Accumulation Condition and Exploration Direction in the Deepwater Area of Qiongdongnan Basin,Northern South China Sea

The deepwater area of southern Qiongdongnan Basin is a hydrocarbon exploration frontier and mainly located on the continental slope in the northwestern South China Sea.Its tectonic and depositional evolution is similar to the typical marginal deepwater areas abroad where oils have been discovered.Favorable hydrocarbon conditions in this area are as follows:(1) three sets of source rocks (including lacustrine mudstone of Eocene,coastal plain coal-bearing strata and semi-closed shallow sea mudstone of Oligocene,and marine mudstone

Deepwater oil and gas field development in South China Sea

This paper focuses on potential development models of future oil and gas exploration in South China Sea. A detailed study of current development models worldwide is performed through some examples of industry installed/ongoing projects and major technical issues encountered during these practice. Key technologies are discussed for the success of field development. Some of the technologies and field development experience can be used for South China Sea project. Several models are studied in field development for different scenarios,including marginal field,large oil field and gas field. With the massive investment activities,continued improved technologies,and rapidly growing pool of professionals,the offshore industry in China will soon encounter a golden period.

New technology opens the door for deepwater development

The paper provided an updated status of technology for deepwater field development, demonstrated the importance of its application through actual project example, and discussed some future technical development trends. The focus was on the floating structures. By reviewing some of the engineering aspects of the project, the technology advancement, innovations and challenges in offshore engineering were discussed and demonstrated. The author’s view of technical challenges facing deepwater forwarding was discussed, which covered water depth limitations, new material application, installation methods, riser development and operational issues. An overview of technologies that will enable deepwater projects to be extended into new frontiers was presented.

Turbidite Petroleum Geology Updates in the Deepwater and Subsalt Gulf of Mexico

The past six years （2008-2014） was a prosperous time for exploration and production in the dGOM （deepwater Gulf of Mexico）. Recent exploration and production activities can be divided into three major categories： drilling new wildcat wells, appraising and developing newly discovered fields and enhanced oil recovery of mature fields. Seismic imaging, complex geology, high pressure drilling, greater depth, and higher temperature are key challenges for the exploration and production of dGOM reservoirs. Complex geology includes salt-related structures and traps, reservoir compartmentalization, and the sequence stratigraphy of turbidite reservoirs. Turbidite sequence stratigraphy helps the asset team to fred the best target intervals. Sheet and channelized sandstones with good downdip aquifer support are preferred reservoir conditions. All the drilling, development and production challenges are related to high pressure, greater depth, higher temperature and lack of existing field analogs. Various IOR （improved oil recovery） methods are studied and applied in the development stage of the Wilcox fields, which have an average primary recovery factor of 10%-15%. With ideal tabular reservoir geometry and IOR methods, recovery factor of the Wilcox reservoirs can reach up to 42% of OOIP （origional oil in place） through the field life cycle.

南海北部陆缘盆地深水区油气勘探新认识及攻关方向

南海北部陆缘盆地深水区已成为我国海洋油气勘探增储上产的重要领域,但由于构造演化史复杂,该区不同凹陷的沉积—构造特征、烃源岩生烃—储层成岩演化和成藏模式均存在明显差异。为准确认识该区油气勘探潜力和方向,基于前人研究成果和勘探实践,在综合分析烃源岩、储层、差异成藏等地质条件的基础上,剖析了南海北部陆缘盆地深水区成藏特征、油气勘探作业面临的挑战,并指出了下一步油气攻关研究方向。研究结果表明:①受地壳拆离作用及强烈薄化影响,该区地层沉积特征特殊,岩石地球物理性质多样;②软流圈差异抬升形成深水区独特的高热流背景,促使区域性湖相、煤型及叠合型等3类烃源灶快速、高强度生烃,生烃门限变浅;③深水盆地群的演化和成盆规模差异大,构造演化控制了盆地几何形态和储集体时空展布,深水区独特的板块构造位置、复杂的构造演化史、温压变化剧烈的地质特征等控制了油气成藏模式。结论认为:①该区油气勘探面临地震资料解析度低、规模有效储层预测困难、勘探成本高等技术与经济的双重挑战;②需要创新形成高地温背景下优质储层差异化分布规律的研究思路;③亟需提升勘探设备能力建设,攻关高效地震采集、“重磁电震”地球物理一体化采集处理、双井架钻探作业、多井段“一趟钻”等勘探关键技术,为我国海洋深水油气勘探开发的高质量发展做好理论和技术支撑。

巴西油气勘探开发历程:从陆上到超深水

21世纪以来,随着桑托斯盆地深水盐下获得一系列重大油气发现,巴西东部海域成为全球深水油气勘探与生产的热点区域。通过全面回顾巴西油气勘探开发历程,系统阐述了从陆上到海域、从浅水到深水—超深水直至盐下勘探的探索实践、战略转变、重大突破和关键理论技术。巴西国家石油公司(简称巴西国油)自1953年成立以后的15年间,在陆上古生界克拉通盆地和断陷盆地进行了勘探,并于断块和三角洲砂体圈闭获得了一些中小型油气发现。20世纪70年代,应用重力流沉积模式和高质量三维地震等勘探新技术,在坎波斯盆地浅水中发现Namorado和Enchova等油田,随后深水盐上勘探获得突破,成功发现Marlim、Roncador等大型油田。21世纪初,通过盐下含油气系统、碳酸盐岩成储成藏模式和核磁共振测井等理论技术攻关,推动桑托斯盆地下白垩统湖相碳酸盐岩陆续获得Tupi(Lula)、Buzios、Mero等世界级超深水盐下大油田的系列重大发现。在复杂的深水作业环境下,油气开发工程面临巨大挑战,巴西国油通过启动深水研发计划(PROCAP),开发并实施窄压力窗口控压钻井、加压钻井液帽钻井、多段智能完井、水下采油及浮式生产平台开发和流动保障等关键技术,显著提升了钻完井、油气田开发和输运的效率及安全性。此外,在浮式采储卸油系统建产规模受限的情况下,推进全球最大规模的CO_(2)捕集、驱油利用与埋存工程(CCUS-EOR),有效减少温室气体排放并提高了原油采收率。上述理论技术的发展和应用,也为全球深水油气勘探开发提供了宝贵经验。未来巴西油气勘探将继续聚焦深水盐下碳酸盐岩和盐上浊积岩,并在古生界天然气等勘探领域持续寻求新的发现,同时通过技术创新和战略合作,促进巴西石油天然气行业的可持续发展。

深水油气高效开发技术装备发展与展望

近年来,深水油气成为国内外油气勘探开发的热点。“十一五”至“十四五”期间,我国深水油气勘探开发取得显著进步,实现从浅水开发到深水开发、合作开发到自营开发、跟跑到并跑甚至局部领跑的“三大跨越”,逐步形成了“区域开发一体评价、少井高产高效开发、智能少人降本增效、高端装备自主可控”的深水油气高效开发理念。中国海油通过立足深水油气勘探高效开发理念,聚焦深水油气高效经济和安全开发,构建了深水油气“勘探—开发—钻采—工程”一体化技术体系,形成了南海北部陆缘深水油气勘探地质理论、深水宽频地震勘探技术、深水油气田储层精细描述技术等10个标志性深水高效开发理论技术,以及地球物理勘探装备、深水半潜式钻井平台及装备等6类高效开发装备。未来将进一步加强深海勘探理论与技术、深水油气田高效开发、超深水钻完井、深水浮式液化天然气开发、全水下油气处理等方面的关键技术与装备攻关,推进我国南海深水油气田高效开发,为我国南海大开发奠定坚实基础。

Characteristics of hydrocarbon accumulation and exploration potential of the northern South China Sea deepwater basins

Although the huge potential of the northern South China Sea deepwater basins has been proven by a series of discoveries that followed the exploration breakthrough of well LW 3-1-1, recent drilling and other studies have demonstrated the uniqueness and complicated nature of hydrocarbon accumulations of the deepwater basins there. Based on a review of previous work and the latest exploration activities and studies, the purpose of this paper is to discuss the critical controls for hydrocarbon accumulations in the deepwater basins of the northern South China Sea. A terrestrial-marine transitional coal-bearing source rock is proposed to be the primary source rock for the deepwater basins. A marine source rock, which was first identified as contributing to hydro-carbon generation in this region, probably plays a significant role in the deep-and ultra-deep water basins south to the Pearl River Mouth and Qingdongnan basins. The shelf margin delta depositional systems in the Baiyun Sag, sourced from the Pearl River, are currently primary exploration targets in the deepwater part of the Pearl River Mouth Basin, whereas the western Red River delta-ic-submarine fan depositional systems, initially proven by drilling, are the possible major exploration reservoirs in the Qing-dongnan deepwater areas. Current deepwater exploration targets at the large-sized structural traps and deep and ultra-deep areas in the south of the Pearl River Mouth and Qingdongnan basins will be the future exploration focus. Deepwater exploration activities and relevant fundamental studies, supporting and promoting each other, are of great importance to the national energy supply of China, the basic regional studies of the South China Sea, advancements in technology, and development of related deepwater industries, and will safeguard national sovereignty and territorial integrity.

世界深水油气勘探形势分析与思考

利用标普全球、睿咨得等商业数据及各油公司的公开信息,对全球深水油气勘探趋势、深水油气发现特点、七大国际油公司深水油气勘探业务布局进行系统分析。结果表明:深水领域是当前全球油气勘探发现最重要的领域,被动大陆边缘盆地深水大发现油气田个数及储量均最多,深水油气大发现对海域新发现油气总储量的贡献最大。岩性油气藏发现越来越多,且油气发现主要分布于中—新生界;七大国际油公司广泛活跃在深水油气勘探和开发各个环节,并发挥着全球引领作用。结合多年对全球油气地质与资源评价形成的理论认识,提出未来有利的深水勘探领域主要集中在大西洋两岸、印度洋周缘、北冰洋周缘等3大领域。提出了开拓海外深水油气勘探业务的6点建议:拓宽多用户地震资料获取渠道,提高深水勘探科学选区水平;加大重点领域深水勘探项目获取力度;灵活进退勘探区块;以大权益获取区块,采用“双勘探模式”经营;加强与深水技术领先国际油公司的合作;提升商务运作能力,逐步实现“非作业者”向“作业者”转变。

Strategies of Efficient Exploration and Development of Deepwater Oil and Gas Overseas

Deepwater offshore area,with rich oil and gas resources,has currently become the hot area for oil and gas exploration and the main battlefield where global oil majors compete with each other.This article summarizes the current situation of deepwater oil and gas exploration and development overseas from the perspectives of exploration history,exploration achievements and technical progress,and analyzes the difficulties and challenges faced by the industry,such as low level understanding of hydrocarbon accumulation conditions,global security and environmental challenges.And then,several feasible implementation strategies have been proposed on how to actively deal with the challenges,promote Chinese oil companies' overseas exploration,and realize efficient exploration and development of deepwater oil and gas fields overseas.These strategies consist of three aspects:profit-oriented operation principle,exploration ideas supported by theory and technology,and exploration strategy that puts safety first.In the era of low oil prices,Chinese oil companies must build up confidence,seize the opportunity and face the challenge while taking efforts to innovate technologies and theories,updates strategic ideas,and cultivate deepwater talents so as to be in an active position in global deepwater exploration and development industry in the future.

Deepwater Hydrocarbon Exploration in China Seas:Yesterday,Today and Tomorrow

Deepwater area has been one of the hottest areas in the global hydrocarbon exploration.However,deepwater hydrocarbon exploration in China started late and mainly concentrated in the South China Sea(SCS) with low level of researches.Although there are some achievements,there are even more challenges.For this reason,this paper reviewed the history of deepwater exploration in China Seas and summarized the current exploration situation.The future directions of deepwater hydrocarbon exploration mainly consist of five aspects:establishing key technology system of complex structure and reservoir seismic acquisition and processing in deepwater areas of SCS,clarifying the development mechanism of high quality source rock and establishing matching assessment technology,studying the formation conditions of favorable reservoir and creating reservoir identification technology,improving accumulation theory of large and medium-sized oil and gas field of deepwater,deepening the researches of petroleum geology conditions of middle and south part of SCS.Simultaneously,the concept of portfolio should be utilized in the exploration process,with economic benefits considered.These understandings will help guiding the future deepwater hydrocarbon exploration in China Seas.

国际大油公司深水油气勘探实践及启示——以圭亚那斯塔布鲁克区块为例

近年来,国际大油公司持续在深水领域取得勘探突破。其中埃克森美孚公司领导的勘探联合体在圭亚那的斯塔布鲁克区块获得31个深水油气田发现,使圭亚那成为南美地区石油行业的重要国家之一,同时也带动了周边海域的勘探热潮。圭亚那盆地横跨圭亚那和苏里南海域,埃克森美孚公司在圭亚那盆地的油气勘探主要经历了3个阶段,分别是1957—1982年超前布局圭亚那盆地苏里南海域;1999—2015年再进圭亚那盆地并长期坚守圭亚那海域;2015年至今地质认识和地震技术助推获得一系列勘探发现。国际大油公司,尤其是埃克森美孚公司领导的勘探联合体在圭亚那的勘探实践表明,开展区域地质综合研究并结合新资料坚定勘探信心,通过引进合作伙伴共担风险、共享收益,是风险勘探的典型做法,可为中国油公司实现从“走出去”迈向“走上去”开展海外油气勘探业务提供借鉴和参考。

Santos Basin Wind Patterns for Planning Offshore Pre-Salt Activities

Santos Basin contains the major hub of oil and gas exploration in Brazil. Consequently, knowledge of ocean surface winds in this area is very important for operational and planning activities. In addition, the importance of renewable energies is nowadays unquestionable, specifically in the case of the wind energy. In this paper, a data clustering technique is applied in order to obtain representative local wind patterns in Santos Basin. Reanalysis data from the National Centers for Environmental Prediction (NCEP) and National Center for Atmospheric Research (NCAR) have been used in this study.

全球油气勘探形势与启示

2022年,全球油气勘探投资、勘探工作量、新发现储量呈现同步增长态势。大—中型油气田储量占比超80%,深水依然是全球勘探发现的重点领域。其中,西南非纳米比亚海域新层系首获近50年最大突破,其发现与共轭类比的勘探思路密不可分;东地中海滚动勘探持续获得发现,归功于国际石油公司紧盯重大发现领域,快速布局周边有利勘探区块,保持一定规模的油气新增储量。分析近10年国际石油公司海外勘探布局和做法表明,公司秉持战略引领,持续加大投资,通过战术布局,进入前沿、新兴和成熟三大领域;依靠创新支撑、把握地质理论发展和勘探技术进步,为油气勘探发现保驾护航。中国油公司“走出去”30年取得良好的勘探成效,但海域勘探与国际石油公司相比仍有一定差距,建议中国油公司风险勘探与滚动勘探并举,大力获取海外深水有利勘探区块,形成资源有效储备。

全球油气勘探开发趋势及对我国油气行业的启示

通过对近20年来全球油气勘探开发投资、油气勘探活动、油气开发活动3个方面进行定性和定量分析,总结提炼出6点油气勘探开发趋势,并提出我国油气行业实现科学可持续发展的启示。预计未来5年全球油气勘探开发投资将回暖,但增速难达2003–2014年时期;勘探投入力度不足,可能引发资源接替问题;天然气勘探开发更受重视;深水油气资源对增储的贡献更加突出;非常规油气地位继续上升。因此,建议我国石油企业应继续保持较高的油气勘探力度,进一步加大天然气勘探开发,加强深水和非常规油气资源开发力度。

南沙海域北康盆地油气地质特征及勘探前景

北康盆地是南沙海域深水油气勘探的潜力地区之一。针对该盆地油气勘探潜力不清的问题,利用地震和钻测井资料,对盆地的油气地质条件开展了综合分析,并探讨了该盆地的有利勘探方向。研究认为:①始新统—渐新统海陆过渡相和和海相泥岩是盆地主力烃源岩,渐新统—下中新统三角洲和滨浅海相砂岩、中新统碳酸盐岩及上中新统—上新统的深海浊积砂岩是主力储层;②盆地主要发育构造圈闭、地层圈闭和构造-岩性复合圈闭3种圈闭类型,长期活动的断层沟通了深部的烃源岩和浅层的圈闭,具有良好的生—运—聚匹配关系;③盆地中部和东南部断拗期发育的碎屑岩构造圈闭可作为首选勘探目标,盆地中部和南部古隆起之上生物礁或碳酸盐岩台地形成的地层圈闭具有良好的勘探潜力,而发育于盆地西部陆坡区由浊积砂体所形成的构造-岩性复合圈闭可作为下一步勘探的重点。本次研究进一步明确了北康盆地的资源潜力和勘探方向,可为该区下一步油气勘探提供参考依据。

Q偏移技术在陵水凹陷气云模糊区地震资料处理中的应用研究

深水石油勘探要求更高品质的地震成像数据作为基础,然而气云区、气烟囱及其他速度异常体等高吸收异常构造的存在,造成深层地震波振幅变弱,频率降低,严重影响目标构造成像精度。本文以陵水凹陷气云模糊区为目标靶区,系统分析工区地震资料品质特点,针对性地采用Q(Geological Quality Factor,地质品质因子)偏移技术补偿浅层气云造成的吸收衰减。首先采用谱比法建立初始的等效Q场;然后基于等效Q场进行Q层析反演建立准确的异常Q场模型;最后基于高精度Q场进行克希霍夫Q叠前深度偏移。实际资料表明,重处理后浅层气云低速异常造成的能量吸收、频率衰减现象得到解决,目的砂体横向连续性更好,有效频带拓宽30%,气云下方模糊区的成像质量得到明显改善,为工区砂体展布落实及后续圈闭目标研究提供了高品质基础资料。