Research Institute of Petroleum Exploration and Development

With Sichuan Basin as focus, this paper introduces the depositional environment, geochemical and reservoir characteristics, gas concentration and prospective resource potential of three different types of shale in China: marine shale, marine-terrigenous shale and terrigenous shale. Marine shale features high organic abundance (TOC: 1.0%–5.5%), high-over maturity (Ro: 2%–5%), rich accumulation of shale gas (gas concentration: 1.17–6.02 m3/t) and mainly continental shelf deposition, mainly distributed in the Paleozoic in the Yangtze area, Southern China, the Paleozoic in Northern China Platform and the Cambrian-Ordovician in Tarim Basin; Marine-terrigenous coalbed carbonaceous shale has high organic abundance (TOC: 2.6%–5.4%) and medium maturity (Ro: 1.1%–2.5%); terrigenous shale in the Mesozoic and Cenozoic has high organic abundance (TOC: 0.5%–22.0%) and mid-low maturity (Ro: 0.6–1.5%). The study on shale reservoirs in the Lower Paleozoic in Sichuan Basin discoveried nanometer-sized pores for the first time, and Cambrian and Silurian marine shale developed lots of micro- and nanometer-sized pores (100–200 nm), which is quite similar to the conditions in North America. Through comprehensive evaluation, it is thought that several shale gas intervals in Sichuan Basin are the practical targets for shale gas exploration and development, and that the Weiyuan-Changning area in the Mid-South of Sichuan Basin, which is characterized by high thermal evolution degree (Ro: 2.0%–4.0%), high porosity (3.0%–4.8%), high gas concentration (2.82–3.28 m3/t), high brittle mineral content (40%–80%) and proper burial depth (1500–4500 m), is the core area for shale gas exploration and development, the daily gas production for Well Wei 201 is 1×104–2×104 m3. ： 以四川盆地为重点，介绍中国海相、海陆过渡相、陆相三大类型页岩形成的沉积环境、地球化学与储集层特征、含气量与远景资源量。中国海相页岩是一套高有机质丰度（TOC为1.0%～5.5%）、高—过成熟（Ro值为2.0%～5.0%）、富含页岩气（含气量1.17～6.02 m3/t）、以陆棚相为主的沉积，主要分布在华南扬子地区古生界、华北地台古生界和塔里木盆地寒武系—奥陶系；海陆过渡相煤系炭质页岩有机质丰度高（TOC为2.6%～5.4%）、成熟度适中（Ro值为1.1%～2.5%）；中新生界陆相页岩有机质丰度高（TOC为0.5%～22.0%）、低熟—成熟（Ro值为0.6%～1.5%）。在对四川盆地下古生界页岩储集层研究中首次发现，寒武系和志留系海相页岩发育大量与北美地区相似的微米—纳米级孔隙。综合评价认为四川盆地发育的多套页岩气层系是勘探开发的现实领域，四川盆地中南部威远—长宁等地区的寒武系和志留系是页岩气勘探开发的核心区与层系，其特点是：热演化程度较高（Ro值为2.0%～4.0%）、孔隙度较高（3.0%～4.8%），含气量较高（2.82～3.28 m3/t）、脆性矿物含量较高（40%～80%）、埋深适中（1 500～4 500 m），有利于开采。图7表7参38

Based on analysis of the characteristics of unconventional hydrocarbon resources, this paper assesses the potential for unconventional hydrocarbons in China, summarizes the key technical progress in exploration and development, and discusses the prospects and developing strategies of unconventional hydrocarbons. The resources of unconventional oil and gas in China are abundant. The recoverable tight gas ranges from 8.8×1012 m3 to 12.1×1012 m3, the recoverable shale gas is from 15×1012 m3 to 25×1012 m3, the recoverable coalbed methane 10.9×1012 m3, the recoverable tight oil from 13×108 t to 14×108 t, and the recoverable shale oil 160×108 t. There is also some resource potential for oil sand. Such key techniques as the full-digital seismic exploration, low permeability and low resistivity reservoirs identification have been developed and their applications in oil and gas fields have achieved good results. Tight gas and tight oil are the most realistic resources to develop in China and the development and utilization of coalbed methane and shale gas are at a pioneer stage. In the next ten or twenty years, the production of unconventional hydrocarbon in China will increase considerably and play a major role in national hydrocarbon resources.

This paper aims to predict the future situation of global energy development. In view of this, we reviewed the history of energy use and understood that new energy sources will usher in a new era following oil & gas, coal and wood one after another in the past time. Although the fossil energy sources are still plenty in the world, great breakthroughs made in some key technologies and the increasing demand for ecological environmental protection both impel the third time of transformation from oil & gas to new energy sources. Sooner or later, oil, gas, coal and new energy sources will each account for a quarter of global energy consumption in the new era, specifically speaking, accounting for 32.6%, 23.7%, 30.0% and 13.7% respectively. As one of the largest coal consumer, China will inevitably face up to the situation of tripartite confrontation of the coal, oil & gas and new energy. The following forecasting results were achieved. First, the oil will be in a stable period and its annual production peak will be around 2040, reaching up to 45 × 108 t. Second, the natural gas will enter the heyday period and its annual production peak will be around 2060, reaching up to 4.5 × 1012 m3, which will play a pivotal role in the future energy sustainable development. Third, the coal has entered a high-to-low-carbon transition period, and its direct use and the discharged pollutants will be significantly reduced. In 2050, the coal will be dropped to 25% of the primary energy mix. Last, the development and utilization of new energy sources has been getting into the golden age and its proportion in the primary energy mix will be substantially enhanced. On this basis, we presented some proposals for the future energy development in China. At first, we should understand well that China's energy production and consumption has its own characteristics. Under the present situation, we should strengthen the clean and efficient use of coal resources, which is the key to solving our energy and environmental issues. Then, under the low oil price circumstance, we should keep 200 million tons of annual oil production as “the bottom line” so as to ensure national energy security and to accelerate tight gas, shale gas and other unconventional resources development. In 2030, the annual natural gas production will reach up to more than 300 Bcm. Finally, the development and utilization of new energy resources should be further strengthened and non-fossil energy sources will be expected to reach as high as 20% of the primary energy consumption by 2030.

Carbon dioxide is an important medium of the global carbon cycle, and has the dual properties of realizing the conversion of organic matter in the ecosystem and causing the greenhouse effect. The fixed or available carbon dioxide in the atmosphere is defined as “gray carbon”, while the carbon dioxide that cannot be fixed or used and remains in the atmosphere is called “black carbon”. Carbon neutral is the consensus of human development, but its implementation still faces many challenges in politics, resources, technology, market, and energy structure, etc. It is proposed that carbon replacement, carbon emission reduction, carbon sequestration, and carbon cycle are the four main approaches to achieve carbon neutral, among which carbon replacement is the backbone. New energy has become the leading role of the third energy conversion and will dominate carbon neutral in the future. Nowadays, solar energy, wind energy, hydropower, nuclear energy and hydrogen energy are the main forces of new energy, helping the power sector to achieve low carbon emissions. “Green hydrogen” is the reserve force of new energy, helping further reduce carbon emissions in industrial and transportation fields. Artificial carbon conversion technology is a bridge connecting new energy and fossil energy, effectively reducing the carbon emissions of fossil energy. It is predicted that the peak value of China's carbon dioxide emissions will reach 110×108 t in 2030. The study predicts that China's carbon emissions will drop to 22×108 t, 33×108 t and 44×108 t, respectively, in 2060 according to three scenarios of high, medium, and low levels. To realize carbon neutral in China, seven implementation suggestions have been put forward to build a new “three small and one large” energy structure in China and promote the realization of China's energy independence strategy.

The main factors controlling the enrichment and high yield of shale gas were analyzed based on the recent research progress of depositional model and reservoir characterization of organic-rich shale in China. The study determines the space-time comparison basis of graptolite sequence in the Upper Ordovician Wufeng Formation–Lower Silurian Longmaxi Formation and proposes the important depositional pattern of marine organic-rich shale: stable ocean basin with low subsidence rate, high sea level, semi-enclosed water body, and low sedimentation rate. Deposited in the stage of Late Ordovician-Early Silurian, the superior shale with thickness of 20−80 m and total organic carbon (TOC) content of 2.0%−8.4% was developed in large deep-water shelf environment which is favorable for black shale development. Based on the comparison among the Jiaoshiba, Changning and Weiyuan shale gas fields, it is believed that reservoirs of scale are mainly controlled by shale rich in biogenic silica and calcium, moderate thermal maturity, high matrix porosity, and abundant fracture. The shales in the Wufeng and Longmaxi formations are characterized by porosity of 3.0%−8.4%, permeability of 0.000 2×10−3−0.500 0×10−3 μm2, stable areal distribution of matrix pore volume and their constituents, great variation in fracture and pore characteristics among different tectonic regions as well as different well fields and different intervals in the same tectonic. The Cambrian Qiongzhusi shale features poor physical properties with the porosity of 1.5%−2.9% and the permeability of 0.001×10−3−0.010×10−3 μm2, resulted from the carbonization of organic matter, high crystallinity of clay minerals and later filling in bioclastic intragranular pores. Four factors controlling the accumulation and high production of shale gas were confirmed: depositional environment, thermal evolution, pore and fracture development, and tectonic preservation condition; two special features were found: high thermal maturity (Ro of 2.0%−3.5%) and overpressure of reservoir (pressure coefficient of 1.3−2.1); and two enrichment modes were summarized: “structural sweet spots” and “continuous sweet area”.

As an important type of “conventional–unconventional orderly accumulation”, shale oil is mature oil stored in organic-rich shales with nano-scale pores. This paper analyzes and summarizes elementary petroleum geological issues concerning continental shale oil in China, including sedimentary environment, reservoir space, geochemical features and accumulation mechanism. Mainly deposited in semi-deep to deep lake environment, shale rich in organic matter usually coexists with other lithologies in laminated texture, and micron to nano-scale pores and microfractures serve as primary reservoir space. Favorable shale mainly has type I and IIA kerogens with a Ro of 0.7%–2.0%, TOC more than 2.0%, and effective thickness of over 10 m. The evolution of shale pores and retained accumulation pattern of shale oil are figured out. Reservoir space, brittleness, viscosity, pressure, retained quantity are key parameters in the “core” area evaluation of shale oil. Continuously accumulated in the center of lake basins, continental shale oil resources in China are about 30×108–60×108 t by preliminary prediction. Volume fracturing in horizontal wells, reformation of natural fractures, and man-made reservoir by injecting coarse grains are some of the key technologies for shale oil production. A three step development road for shale oil is put forward, speeding up study on “shale oil prospective area”, stepping up selection of “core areas”, and expanding “test areas”. By learning from marine shale breakthroughs in North America, continental shale oil industrialization is likely to kick off in China.

Abstract The Ordos basin is the oldest and still an important hydrocarbon province in central China. It is a typical cratonic basin developed on the Archean granulites and lower Proterozoic greenschists of the North China block. The development of the Ordos basin during the Paleozoic–Mesozoic can be divided into three evolutionary stages: Cambrian–Early Ordovician cratonic basin with divergent margins; Middle Ordovician–Middle Triassic cratonic basin with convergent margins; and Late Triassic–Early Cretaceous intraplate remnant cratonic basin. Two hydrocarbon systems are present in the basin: the Paleozoic gas and Mesozoic oil systems. In the Paleozoic gas system, the Lower Ordovician marine carbonates and Pennsylvanian–Lower Permian coal measures serve as source rocks. The Lower Ordovician karst-modified dolomites and Pennsylvanian bauxitic mudstones form a significant reservoir-seal association, and the Pennsylvanian–Lower Permian deltaic sandstones and Upper Permian lacustrine mudstones form another effective reservoir-seal association. In the Mesozoic oil system, the Upper Triassic lacustrine mudstones are mature source rocks. The Upper Triassic deltaic sandstones and overlying shallow-lacustrine and swamp mudstones form a reservoir-seal association, and the Lower Jurassic fluvial sandstones and overlying shallow-lacustrine and swamp mudstones form another reservoir-seal association. In both hydrocarbon systems, the stratigraphic variations provide the principal traps. The Ordos basin is characterized by a stable tectonic setting that controlled the distribution of depositional systems and the development of erosional surfaces and ultimately governed the distribution of oil and gas fields and trap types.

This paper mainly discusses the industrialization progress, “sweet spot” evaluation criterion, E&P technologies, success experiences, challenges and prospects of China's shale gas. Based on the geologic and engineering parameters of the Fuling, Changning and Weiyuan shale gas fields in the Sichuan Basin, this paper points out that China's shale gas has its particularity. The discoveries of super-giant marine shale gas fields with high evolution degree (Ro=2.0%−3.5%) and ultrahigh pressure (pressure coefficient=1.3−2.1) in southern China is of important scientific significance and practical value to ancient marine shale gas exploration and development to China and even the world. It's proposed that shale gas “sweet spots” must be characterized by high gas content, excellent frackability and good economy etc. The key indicators to determine the shale gas enrichment interval and trajectory of horizontal wells include “four highs”, that is high TOC (>3.0%), high porosity (>3.0%), high gas content (>3.0 m3/t) and high formation pressure (pressure coefficient>1.3), and “two well-developed” (well-developed beddings and well-developed micro-fractures). It's suggested that horizontal well laneway be designed in the middle of high pressure compartment between the Upper Ordovician Wufeng Formation and Lower Silurian Longmaxi Formation. The mode of forming “artificial shale gas reservoir” by “fracturing micro-reservoir group” is proposed and the mechanisms of “closing-in after fracturing, limiting production through pressure control” are revealed. Several key technologies (such as three-dimensional seismic survey and micro-seismic monitoring of fracturing, horizontal wells, “factory-like” or industrialized production mode, etc.) were formed. Some successful experiences (such as “sweet spot” selection, horizontal well laneway control, horizontal length optimization and “factory-like” production mode, etc.) were obtained. The four main challenges to realize large-scale production of shale gas in China include uncertainty of shale gas resources, breakthroughs in key technologies and equipment of shale gas exploration and development below 3 500 m, lower cost of production, as well as water resources and environment protection. It is predicted that the recoverable resources of the Lower Paleozoic marine shale gas in southern China are approximately 8.8×1012 m3, among which the recoverable resources in the Sichuan Basin are 4.5×1012 m3 in the favorable area of 4.0×104 km2. The productivity of (200−300)×108 m3/a is predicted to be realized by 2020 when the integrated revolution of “theory, technology, production and cost” is realized in Chinese shale gas exploration and development. It is expected in the future to be built “Southwest Daqing Oilfield (Gas Daqing)” in Sichuan Basin with conventional and unconventional natural gas production.

Continental shale oil has two types, low-medium maturity and medium-high maturity, and they are different in terms of resource environment, potential, production methods and technologies, and industrial evaluation criteria. In addition, continental shale oil is different from the shale oil and tight oil in the United States. Scientific definition of connotations of these resource types is of great significance for promoting the exploration of continental shale oil from “outside source” into “inside source” and making it a strategic replacement resource in the future. The connotations of low-medium maturity and medium-high maturity continental shale oils are made clear in this study. The former refers to the liquid hydrocarbons and multiple organic matter buried in the continental organic-rich shale strata with a burial depth deeper than 300 m and a Ro value less than 1.0%. The latter refers to the liquid hydrocarbons present in organic-rich shale intervals with a burial depth that in the “liquid window” range of the Tissot model and a Ro value greater than 1.0%. The geological characteristics, resource potential and economic evaluation criteria of different types of continental shale oil are systematically summarized. According to evaluation, the recoverable resources of in-situ conversion technology for shale oil with low-medium maturity in China is about (700–900)×108 t, and the economic recoverable resources under medium oil price condition ($ 60–65/bbl) is (150–200)×108 t. Shale oil with low-medium maturity guarantees the occurrence of the continental shale oil revolution. Pilot target areas should be optimized and core technical equipment should be developed according to the key parameters such as the cumulative production scale of well groups, the production scale, the preservation conditions, and the economics of exploitation. The geological resources of medium-high maturity shale oil are about 100×108 t, and the recoverable resources can to be determined after the daily production and cumulative production of a single well reach the economic threshold. Continental shale oil and tight oil are different in lithological combinations, facies distribution, and productivity evaluation criteria. The two can be independently distinguished and coexist according to different resource types. The determination of China's continental shale oil types, resources potentials, and tight oil boundary systems can provide a reference for the upcoming shale oil exploration and development practices and help the development of China's continental shale oil.

The Xiamaling Formation in the North China Block contains a well-preserved 1400 Ma sedimentary sequence with a low degree of thermal maturity. Previous studies have confirmed the dynamic and complex nature of this evolving marine setting, including the existence of an oxygen-minimum zone, using multi-proxy approaches, including iron speciation, trace metal dynamics, and organic geochemistry. Here, we investigate the prevailing redox conditions during diagenesis via the biomarkers of rearranged hopanes from the finely laminated sediments of the organic-rich black shales in Units 2 and 3 of the Xiamaling Formation. We find that rearranged hopanes are prominent in the biomarker composition of the oxygen-minimum zone sediment, which is completely different from that of the sediment in the overlying anoxic strata. Since the transition process from hopanes to rearranged hopanes requires oxygen via oxidation at the C-l6 alkyl position of 17α(H)-hopanes, we infer that dissolved oxygen led to the transformation of hopane precursors into rearranged hopanes during the early stages of diagenesis. The use of hopanoid hydrocarbons as biomarkers of marine redox conditions has rarely been previously reported, and the hydrocarbon signatures point towards oxic bottom waters during the deposition of Unit 3 of the Xiamaling Formation, which is consistent with the earlier oxygen-minimum zone environmental interpretation of this Unit.

Solid polymer electrolytes (SPEs) and hydrogel electrolytes were developed as electrolytes for zinc ion batteries (ZIBs). Hydrogels can retain water molecules and provide high ionic conductivities; however, they contain many free water molecules, inevitably causing side reactions on the zinc anode. SPEs can enhance the stability of anodes, but they typically possess low ionic conductivities and result in high impedance. Here, we develop a lean water hydrogel electrolyte, aiming to balance ion transfer, anode stability, electrochemical stability window and resistance. This hydrogel is equipped with a molecular lubrication mechanism to ensure fast ion transportation. Additionally, this design leads to a widened electrochemical stability window and highly reversible zinc plating/ stripping. The full cell shows excellent cycling stability and capacity retentions at high and low current rates, respectively. Moreover, superior adhesion ability can be achieved, meeting the needs of flexible devices.

The Anyue Sinian–Cambrian giant gas field was discovered in central paleo-uplift in the Sichuan Basin in 2013, which is a structural-lithological gas reservoir, with 779.9 km2 proven gas-bearing area and 4 403.8×108 m3 proven geological reserves in the Cambrian Longwangmiao Formation in Moxi Block, and the discovery implies it possesses trillion-cubic-meter reserves in the Sinian. Cambrian Formations in Sichuan Basin. The main understandings achieved are as follows: (1) Sinian–Cambrian sedimentary filling sequences and division evidence are redetermined; (2) During Late Sinian and Early Cambrian, “Deyang–Anyue” paleo-taphrogenic trough was successively developed and controlled the distribution of source rocks in the Lower-Cambrian, characterized by 20–160 m source rock thickness, TOC 1.7%–3.6% and Ro 2.0%–3.5%; (3) Carbonate edge platform occurred in the Sinian Dengying Formation, and carbonate gentle slope platform occurred in the Longwangmiao Formation, with large-scale grain beach near the synsedimentary paleo- uplift; (4) Two types of gas-bearing reservoir, i.e. carbonate fracture-vug type in the Sinian Dengying Formation and dolomite pore type in the Cambrian Longwangmiao Formation, and superposition transformation of penecontemporaneous dolomitization and supergene karst formed high porosity-permeability reservoirs, with 3%–4% porosity and (1–6)×10−3 μm2 permeability in the Sinian Dengying Formation, and 4%–5% porosity and (1–5)×10−3 μm2 permeability in the Cambrian Longwangmiao Formation; (5) Large paleo-oil pool occurred in the core of the paleo-uplift during late Hercynian—Indosinian, with over 5 000 km2 and (48–63)×108 t oil resources, and then in the Yanshanian period, in-situ crude oil cracked to generate gas and dispersive liquid hydrocarbons in deep slope cracked to generate gas, both of which provide sufficient gas for the giant gas field; (6) The formation and retention of the giant gas field is mainly controlled by paleo-taphrogenic trough, paleo-platform, paleo-oil pool cracking gas and paleo-uplift jointly; (7) Total gas resources of the Sinian–Cambrian giant gas field are preliminarily predicted to be about 5×1012 m3, and the paleo-uplift and its slope, southern Sichuan Basin depression and deep formations of the high and steep structure belt in east Sichuan, are key exploration plays. The discovery of deep Anyue Sinian–Cambrian giant primay oil-cracking gas field in the Sichuan Basin, is the first in global ancient strata exploration, which is of great inspiration for extension of oil & gas discoveries for global middle-deep formations from Lower Paleozoic to Middle–Upper Proterozoic strata.

Fourier transform infrared spectroscopy (FTIR) can provide crucial information on the molecular structure of organic and inorganic components and has been used extensively for chemical characterization of geological samples in the past few decades. In this paper, recent applications of FTIR in the geological sciences are reviewed. Particularly, its use in the characterization of geochemistry and thermal maturation of organic matter in coal and shale is addressed. These investigations demonstrate that the employment of high-resolution micro-FTIR imaging enables visualization and mapping of the distributions of organic matter and minerals on a micrometer scale in geological samples, and promotes an advanced understanding of heterogeneity of organic rich coal and shale. Additionally, micro-FTIR is particularly suitable for in situ, non-destructive characterization of minute microfossils, small fluid and melt inclusions within crystals, and volatiles in glasses and minerals. This technique can also assist in the chemotaxonomic classification of macrofossils such as plant fossils. These features, barely accessible with other analytical techniques, may provide fundamental information on paleoclimate, depositional environment, and the evolution of geological (e.g., volcanic and magmatic) systems.

Abstract Electrochemical water splitting for H 2 production is limited by the sluggish anode oxygen evolution reaction (OER), thus using hydrazine oxidation reaction (HzOR) to replace OER has received great attention. Here we report the hierarchical porous nanosheet arrays with abundant Ni 3 N‐Co 3 N heterointerfaces on Ni foam with superior hydrogen evolution reaction (HER) and HzOR activity, realizing working potentials of −43 and −88 mV for 10 mA cm −2 , respectively, and achieving an industry‐level 1000 mA cm −2 at 200 mV for HzOR. The two‐electrode overall hydrazine splitting (OHzS) electrolyzer requires the cell voltages of 0.071 and 0.76 V for 10 and 400 mA cm −2 , respectively. The H 2 production powered by a direct hydrazine fuel cell (DHzFC) and a commercial solar cell are investigated to inspire future practical applications. DFT calculations decipher that heterointerfaces simultaneously optimize the hydrogen adsorption free energy (Δ G H* ) and promote the hydrazine dehydrogenation kinetics. This work provides a rationale for advanced bifunctional electrocatalysts, and propels the practical energy‐saving H 2 generation techniques.

Petroleum geology is evolving into two branches, conventional petroleum geology and unconventional petroleum geology, with the latter becoming a new theoretical frontier in the petroleum industry. The core of conventional hydrocarbon geological study is based on identifying the match between source rock, reservoir, caprock, migration, trap, preservation and timing; the core of unconventional hydrocarbon geological study evaluates if the oil and gas is part of a continuous accumulation, where stress is placed on the evaluation of “lithology, physical properties, brittleness, oiliness, source rock features, stress anisotropy” and their configuration. The oil and gas accumulation mode and theoretical formula at various low limits of pore throat diameter have been established, as well as the “L” type production curve. Theoretical production prediction models for unconventional oil and gas, and formation mechanism and development patterns for unconventional oil and gas are being revealed. The connotation, characteristics, potential and technology for unconventional oil and gas have been observed, and two key marks to identify unconventional hydrocarbon have been put forward: (1) continuous distribution of hydrocarbon-bearing reservoirs over a large area, with no obvious trap boundary; and (2) no natural stable industrial production, and no obvious Darcy flow. Systematic research shows that the proportion of global unconventional to conventional hydrocarbon resources is 8:2, in which the unconventional oil is almost equal to conventional oil, and the unconventional gas is about 8 times that of conventional gas. In China, unconventional oil resources are about 240×108 t and unconventional gas resources are about 100×1012 m3. In recent years the development of tight gas and tight oil should be strengthened to realize industrial reserves and increase production. Construction of shale gas pilot plants and shale oil research should be strengthened. Unconventional oil and gas industrial systems and research should be set up, including unconventional hydrocarbon geology, fine particle sedimentology, unconventional reservoir geology, seismic reservoir prediction, massive fracturing of horizontal wells, “factory-like” operation, low cost management and subsidy policy and personnel training.

Since the Neoproterozoic, two important cycles of separation and junction of the Rodinia and Pangea supercontinents controlled the formation of the Tethys, Laurasia, Gondwana and Pacifica domains, as well as the sedimentary basin types including craton, passive margin, rift, foreland, fore-arc, and back-arc basins. Sixty-eight percent of the discovered reserves are from the Tethys domain, while 49% of the undiscovered possible reserves are in passive margin basins. Six major sets of source rocks, two types of reservoirs (carbonates and clastics), and two regional seals (shale and evaporite) formed in global evolution of basins. Ten patterns are summarized from the above factors controlling the distribution of global hydrocarbon resources. (1) Conventional-unconventional hydrocarbon is accumulated “orderly”. (2) Distribution of Tethys controls the accumulation of the global hydrocarbons. (3) Foreland thrusting zones control the distribution of structural oil/gas fields; (4) Intra-craton uplifts control the distribution of giant oil/gas fields; (5) Platform margins control the banded distribution of giant organic reef and bank type oil/gas fields. (6) Passive margins control the distribution of giant marine oil/gas fields. (7) Foreland deep slopes control the occurrence of large scale heavy oil and bitumen. (8) Basin deposition slopes control the accumulation of tight oil & gas and coalbed methane. (9) Organic rich deep basin sediments control the retention of shale oil and gas. (10) Low temperature and high pressure seafloor sediments control the distribution of hydrate. The conventional/unconventional resources ratio is 2:8. The conventional resources are mainly distributed in the Middle East, Russia, North America, and Latin America. The unconventional resources are mainly distributed in North America, Asia Pacific, Latin America, and Russia. According to the ten trends of global petroleum industry, hydrocarbon exploration is mainly focused on marine deep water, onshore deep layer, and unconventional oil & gas. The peak of oil production will probably come around 2040, and the life span of petroleum industry will last another 150 years. Renewable energy will replace fossil energy, not for the exhaustion of fossil energy, but because it is cheaper and cleaner.

Summary Preformed particle gel (PPG) has been successfully synthesized and applied to control excess water production in most of the mature, waterflooded oil fields in China. This paper reports on laboratory experiments carried out to investigate PPG transport mechanisms through porous media. Visual observations in etched-glass micromodels demonstrate that PPG propagation through porous media exhibits six patterns of behavior: direct pass, adsorption, deform and pass, snap-off and pass, shrink and pass, and trap. At the macroscopic scale, PPG propagation through porous media can be described by three patterns: pass, broken and pass, and plug. The dominant pattern is determined by the pressure change with time along a tested core (as measured at specific points), the particle-size ratio of injected and produced particles from the core outlet, and the residual resistance factor of each segment along the core. Measurements from micromodel and routine coreflooding experiments show that a swollen PPG particle can pass through a pore throat with a diameter that is smaller than the particle diameter owing to the elasticity and deformability of the swollen PPG particle. The largest diameter ratio of a PPG particle and a pore throat that the PPG particle can pass through depends on the swollen PPG strength. PPG particles can pass through porous media only if the driving pressure gradient is higher than the threshold pressure gradient. The threshold pressure depends on the strength of the swollen PPG and the ratio of the particle diameter and the average pore diameter.

Surface atomic arrangement and coordination of photocatalysts highly exposed to different crystal facets significantly affect the photoreactivity. However, controversies on the true photoreactivity of a specific facet in heterogeneous photocatalysis still exits. Herein, we exemplified well-defined BiOBr nanosheets dominating with respective facets, (001) and (010), to track the reactivity of crystal facets for photocatalytic water splitting. The real photoreactivity of BiOBr-(001) were evidenced to be significantly higher than BiOBr-(010) for both hydrogen production and oxygen evolution reactions. Further in situ photochemical probing studies verified the distinct reactivity is not only owing to the highly exposed facets, but dominated by the co-exposing facets, leading to an efficient spatial separation of photogenerated charges and further making the oxidation and reduction reactions separately occur with different reaction rates, which ordains the fate of the true photoreactivity.

Global petroleum exploration is currently undergoing a strategic shift from conventional to unconventional hydrocarbon resources. Unconventional hydrocarbons in tight reservoirs show characteristics distinct from those of conventional hydrocarbon sources hosted in structural and stratigraphic traps. The characteristic features include the following: a hydrocarbon source and reservoir coexist; porosity and permeability are ultra-low; nano-pore throats are widely distributed; hydrocarbon-bearing reservoir bodies are continuously distributed; there is no obvious trap boundary; buoyancy and hydrodynamics have only a minor effect, and Darcy's law does not apply; phase separation is poor; there is no uniform oil–gas–water interface or pressure system; and oil or gas saturation varies. Examples of unconventional hydrocarbon accumulations are the Mesozoic tight sandstone oil province and the Upper Paleozoic tight sandstone gas province in the Ordos Basin, north-central China. Generally, continuous hydrocarbon accumulation over a large area is a distinguishing characteristic of unconventional hydrocarbon sources. Because of the great potential of unconventional petroleum resources, it is believed that research on such resources will be at the forefront of the future development of petroleum geology.

Abstract We conducted organic geochemical analyses on the largest suite of oils and source-rock extracts from the Tarim basin, northwest China, currently available. Statistical cluster analysis of the entire suite of Tarim oils distinguishes at least seven genetic groups of oils. The largest group of oils was collected from the Tazhong and Tabei uplifts and originated from marine Middle-Upper Ordovician anoxic marls that mark slope facies at the margins of structural uplifts. Two other genetic groups most likely originated from marine Middle-Upper Ordovician source rocks, but of distinct facies, with one an oxic shale-rich source west of the Bachu uplift and the other an anoxic shale source at Tazhong. Other genetic oil groups originated from various nonmarine source rocks. The largest of these groups consists of oils from the Luntai uplift, which best correlate with Jurassic lacustrine mudstones in the Kuqa depression, although Triassic lacustrine mudstones cannot be eliminated as a source for these oils. Two oils from southwest Tarim are highly mature. Despite uncertainty due to low biomarker concentrations, these oils probably originated from nonmarine shaly source rocks. The two remaining genetic groups consist of single oil samples: Yi603 (an oil likely derived from coal in the Kuqa depression) and Qu1 (derived from Carboniferous or Jurassic shaly source rock from the west flank of the Bachu uplift). Sample 63KLT (a seep sample from west of Kashi) has attributes of a lacustrine source rock and clusters with oils from Luntai. These results suggest that numerous source rocks occur in the basin, but they likely are areally restricted. Our results do not support previous published work that suggests that hypothesized euxinic source rocks might account for reserves of up to 350 billion bbl of oil.