There are some difficulties caused by lower signal-to-noise ratio in the signal processing of leakage detection for pipeline.It is possible to enhance the signal-to-noise ratios of pressure and flow rate signals in a pipeline by using the adaptive noise cancellation based on adaptive fuzzy neural network system (AFNNS). The AFNNS has the abilities of nonlinear mapping and self-learning property and can be used to achieve the nonlinear model of the noise. The adaptive noise cancellation based on the AFNNS can achieve an optimal reconstruction of signals and a desired robust against the effect of uncertainties in signal processing. The application of this system shows that the noise filter based on AFNNS can not only obtain simplicity of implementation and conservation of operation time,but also achieve better reconstruc-tion performance in the pressure and flow signal processing for the leakage detection of pipeline.

Characteristics of boundary faults are of significance in researches on the evolution and formation mechanism of sedimentary basins. Based on the analysis of geological and geophysical data, we examined the relationship between the boundary faults, i.e. the Xinanzhuang fault (XNZF) and Baigezhuang fault (BGZF) in Nanpu sag. The paleo-stress field evolution and features of boundary faults were studied by analyzing occurrences and activity differential of various segments of the two faults and their spatial relations to depocenters and contemporaneous faults, consequently, a new formation mechanism for Nanpu sag was proposed. Seiscrops, gravity anomaly distributions and seismic sections revealed that the XNZF and BGZF converged successively with no distinct host-slave correlation and mutual overlapping, behaving like the same fault (the Xi-Bai fault for short). However, each segment has a difference:the XNZF with a dip angle of 43° shows a curved strike and bending fractured surface, whereas the BGZF with a dip angle of 57°~69° has a straight strike and planar fractured surface. Besides, the paleo-downthrow calculation of the boundary faults showed that the XNZF was strongly active as a whole in Paleogene, while the BGZF remained inactive except for the Gaoliu structural zone that acted violently in late Eocene to Oligocene. The comparison of spatial distributions of the contemporaneous faults, depocenters and boundary faults demonstrated that the tectonic evolution of Nanpu sag can be divided into three stages:during the Es₃ to Es₂ deposition, controlled by NE-orientated contemporaneous faults, depocenters extended in the NE direction, indicating a NW-orientated extension of the basin; during the Es₁ to Ed deposition, depocenters shifted in both the NE and the NW directions and there occurred an violent NW-orientated left-lateral strike-slip fault in the basin with an NW-orientated extension; and since Ng deposition, depocenters have experienced continuous transtension due to the joint influence of the NEE-and NW-orientated faults. Correspondingly, the paleo-stress field evolution of Nanpu sag can be divided into three episodes, namely the weakly, strongly and stably transtensional episodes. The present study suggested that Nanpu sag was formed by the XNZF extension along the left-lateral strike-slip direction of the BGZF, consequently, a new genetic pattern was proposed that Nanpu sag in Paleogene should be a classic transtensional fault-termination basin.

It is an inevitable trend for oil and gas industry to transform exploration & development domain from conventional hydrocarbon accumulations to unconventional hydrocarbon ones, which are obviously different in types, geological features and genesis. Conventional petroleum focuses on accumulation mechanism, and the key answer is whether the trap contains petroleum, otherwise, unconventional petroleum focuses on the reservoir space, and the key answer is how much the reservoirs capture petroleum. Unconventional hydrocarbon resources are mainly characterized by continuous distribution and no natural oil and gas production from per well. Currently, unconventional problems occur in the exploration and development of conventional hydrocarbon resources, thus it is necessary to transform unconventional hydrocarbon resources into new “conventional” hydrocarbon resources. With technology development, unconventional hydrocarbons can be transformed into conventional ones. Generally, conventional hydrocarbon deposits consist of structural and litho-stratigraphic hydrocarbon reservoirs, where oil and gas are distributed in an isolated structure or a larger structure group with clear trap boundaries and pore-throat systems in millimeter-micrometer scale. Oil and gas in this case accumulate by buoyancy to form hydrocarbon pools. However, unconventional hydrocarbon accumulations, including tight sandstone oil and gas, tight carbonate oil and gas, shale oil and gas, coal-bed methane, oil shale, oil sand, hydrate, etc., are distributed continuously or quasi-continuously in basin's slopes or centers. Commonly, they are characterized by source-reservoir paragenesis and have no distinct trap boundaries. Pore-throat systems in nanometer scale are well-developed in unconventional reservoir rocks, and related hydrocarbons are mainly detained in situ or migrate for a short distance into reservoirs that are close to source rocks because buoyancy is limited. The present paper systematically analyzed geological characteristics and exploration potential of tight hydrocarbons in some typical basins of China, where pores in nanometer scale with partial micrometer-millimeter pores dominate the reservoir space of unconventional hydrocarbons, the diameter of reservoir pores is 5~200 nm in gas shale, 40~500 nm in tight oil limestone, 50~900 nm in tight oil sandstone and 40~700 nm in tight gas sand. In terms of the rapid development of globe petroleum industry and nano-technology, a concept of nano-hydrocarbons is proposed in this paper that indicates that “nano-hydrocarbon” is the development direction of oil and gas industry in the future, urgently requiring developing vicarious technologies, such as nano-hydrocarbon perspective viewing mirror, nano-hydrocarbon displacement agent and nano-hydrocarbon exploitation robots. Petroleum intellectualization times will come in following.

The shale oil and gas revolution has prolonged the life cycle of oil industry in the world, and promoted the growth of global oil and gas reserves and production, thus having influences on the energy strategy of each country. The formation and evolution of organic-rich shale worldwide were controlled by the life explosion and mass extinction events in the past geological periods. In combination with the worldwide exploration and development of shale oil and gas, the shale oil and gas revolution involves scientific and technological revolution, management revolution and strategic revolution. Through the scientific and technological revolution, the resource-based view is expanded from a single resource type to a "source rock bearing oil and gas" system; the efficient and low-cost development of shale oil and gas are realized by the management revolution; a new map of the worldwide energy is reshaped by the strategic revolution. Through systematically introducing the industrial practices in terrestrial shale oil and marine/terrestrial shale gas, it is clear that the underground in-situ heating conversion technology represents the actual exploration of the large-scale development and utilization of shale oil resources with medium-low maturity, and the volume fracturing technology for horizontal well is an effective way to realize the low-cost development of shale oil resources with medium-high maturity. It is pointed out that the shale oil with medium-low maturity in the Member 7 of Yanchang Formation in Ordos Basin and that with medium-high maturity in the Daanzhai Member of Jurassic Ziliujing Formation of Sichuan Basin have great resource potential. At present, China has achieved a success in the development of marine shale gas shallower than 3500 m, and major breakthroughs have been made in the exploration of transitional and marine shale gas deeper than 3 500 m. The underground coal gasification test represents an exploration way for achieving clean and sustainable use of coal. The shale oil and gas revolution has a profound impact on China's energy development. It breaks through the traditional oil exploration theories by introducing "source rock bearing oil and gas" as a new petroleum system, drives the technological explosion, speeds up the energy type alternation, opens the development path of "depending on conventional petroleum, making a breakthrough in unconventional petroleum, and developing new energy", which is expected to achieve energy independence in China.

Based on the generalized Darcy’s law that considers a comprehensive influence of the threshold pressure gradient and the pressure-sensitive effect, we proposed transient seepage theories on infinite- and finite-conductivity vertically fractured wells respectively, which follow the elliptic seepage theory and average mass conservation law. A production decline model for fractured horizontal wells with arbitrary numbers of transverse hydraulic fractures was then established on the basis of the superposition principle, and accordingly production decline laws of fractured horizontal wells at unsteady-state periods were investigated. The results show that the initial production of multi-fractured horizontal wells(MFHW) is relatively high but soon followed by a sharp decline. Then, the production keeps in a relatively stable state and declines slowly. The greater the threshold pressure gradient and the deformation coefficient, the lower the per-well production of MFHW will be. Furthermore, the threshold pressure gradient will influence the production and decline laws of MFHW remarkably when it exceeds 0.01MPa/m. The more the hydraulic fracture numbers the longer the fracture length and the bigger the flow conductivity, and then the higher the production of MFHW and the faster the decline rate will be. However, the increase amplitude will be getting smaller and smaller along with the increase of hydraulic fracture numbers, fracture length and flow conductivity.

The reservoirs in T Oilfield are characterized by anisotropy and inhomogeneity, whose lithology are composed of marine dolomite and limestone. The petro-physical evaluation for the reservoirs was made using data from new logging methods. Based on the conventional evaluation results, the reservoirs were divided into four types, and the accumulation property of the reservoir was evaluated applying XRMI log. WSTT and XRMI were combined to evaluate the validity and distribution of fractures. The log data from NMR was integrated with the conventional log to identify fluids of reservoir and calculate reservoir saturation, which is proved to be correct by using DST results in 25 thin layers of four wells.

The Sulige gas field with a gas-bearing area of about 4×10⁴km² in the Ordos Basin is one of the largest gas fields discovered in China up to now. It belongs to a sandstone lithologic gas reservoir characteristics of low porosity, low permeability, low abundance, low yield but large-scale distribution. Analyses on geochemistry, occurrence attitude and origin of formation water showed that the formation water in the Sulige gas field was characterized by chloride calcium type, slight acidity, total salinity of 29.12 g/L～68.30 g/L, δ²D value of -82.7‰～-60.5‰, δ¹⁸O value of -6.3‰～-3.39‰, and ⁸⁷Sr / ⁸⁶Sr value of 0.71365～0.71718, indicating a palaeo-depositional formation water in a mutually unconnected and deeply closed environment. The distribution of the formation water was mainly controlled by the intensity of hydrocarbon generation and the heterogeneity of reservoirs rather than regional structures, and it was relatively independent, discontinuous, and lacking in a uniform gas-water interface.

Puguang Gas Field as the largest gas field of Sichuan Basin is also the biggest marine carbonate formational gas reservoir. In addition, Puguang Gas Field has highlights in several aspects such as the deepest burial condition, the highest reserves abundance, excellent reservoir quality, the thickest reservoir bed, the highest quantity of H ₂S and the biggest dry coefficient of natural gas. Puguang Gas Field has the special condition of reservoir-forming, which is in virtue of some factors, including the repeated infusion of the multiple hydrocarbon and high quality of hydrocarbon, the dynamic matches of channel system and the processes of generation and expulsion of hydrocarbon, the development of reservoir bed at the edge of evaporated plateau and the high-energy oolite facies, the highly formation of the secondary porosity due to the late dolomization and intense acid corrosion, the paleo-tectonic bulges and long-term received hydrocarbon, the occurrence of thermochemical sulfate reduction and the highly development of secondary porosity in reservoir bed, the optimism of the performance of reservoir bed, as well as the effectiveness barrier of thick gypsum rock in Jialingjiang and Leikoupo formations overlying Feixianguan Formation.

The tight oil refers to an oil that accumulates in source rocks in a free or adsorbed state or in tight sandstones and carbonates interbedded with or adjacent to source rocks. Generally, this oil accumulation has not yet experienced a large-scale, long-distance migration. Based on the clarity of the tight oil concept and connotation, we proposed ten key indices to evaluate the tight oil. Tight oil reservoirs can be generally divided into 3 different types based on porosity and permeability, while the tight oil itself can be also classified into 3 types depending on the genetic relationship of a close contact between tight reservoirs and source rocks, i.e. ①tight oil in lacustrine carbonate rocks; ②tight oil in deep-lake gravity flow sandstones and ③tight oil in deep-lake delta sandstones. The tight oil is widely distributed in China, currently, a number of important exploration discoveries of the tight oil have been achieved in the Triassic Chang-6 and Chang-7 sections of Yanchang Formation in the Ordos Basin, the Permian Lucaogou Formation in the Junggar Basin, the Middle-Lower Jurassic of the Sichuan Basin and the Cretaceous Qingshankou-Quantou Formation of the Songliao Basin. To expect the tight oil prospect in China, we preliminary forecast that the tight oil geological resources in China are about (106.7~111.5 ) ×10⁸ t. Combined with the analysis of future prospects of petroleum development, we can come to a conclusion that the tight oil in China should be a realistic replacement resource of the conventional oil.

Green Earth is common homeland for human survival and development. Climate change has been a severe challenge to the earth's ecosystem since the global industrialization. Energy is the fundamental issue of human society. World energy transition is defined as the development trend of human energy utilization from firewood to coal, coal to oil and gas, oil and gas to new energy, and from carbon energy to carbon free energy and the process of fundamental transition for main energy factors including energy form, energy technology, energy mix and energy management.Energy system consisted with "New energy"+"Smart energy" and characterized with clean, carbon free, intelligent and efficient as the core is the development trend and direction of world energy transition. The world energy transition has "two driving forces and one pushing force", that is, the internal driving force is the spatial and regional imbalance of the world energy pattern, the external driving force is the gradual rise of new energy competitiveness, and the pushing force is the scientific and industrial revolution with the core of scientific innovation and technological progress. World energy transition has four connotations:politics, technology, management and commerce. The political synergy with the core of consultation and global cooperation mechanism is the political connotation of world energy transition; the transformation from resource-based to technology-based energy system is the technical connotation of world energy transition; the continuous improvement of intelligent level is the management connotation of world energy transition; the transformation from international oil companies to international energy companies, the business model transformation is the business connotation of the world energy transition. The pathway of world energy transition is that the international community gradually realizing the low-carbon revolution of fossil energy, the low-cost revolution of new energy and the intelligent revolution of energy management through political coordination, science and technology promotion, management driving and business pushing, promoting the transformation of the world primary energy consumption structure from fossil energy to non-fossil, clean new energy, and promoting the energy production and supply system to green, clean, efficient and safe, achieving "carbon neutral" between human energy utilization and the earth's carbon cycle system, and effectively coping with global climate change. World energy transition is an inevitable choice to achieve national and regional energy security, a new driving force to promote world economic development and economic growth, a new driving force for world GDP growth, a new force to reshape the world political pattern, an effective measure to fulfill the requirements of the Paris Agreement, achieve the goal of "carbon neutrality"in energy utilization, and cope with global climate change.China is the world's largest energy producer, consumer and carbon emitter. The proposal of development goal of "striving to reach carbon dioxide emissions at peak by 2030, and striving to achieve carbon neutrality by 2060" will accelerate the transition for fossil energy to new energy, realize the "energy revolution", ensure the security of energy supply, and promote the harmonious development of human society and the natural environment in China.

The Permit H of the Republic of Chad is the largest high-risky exploration block owned by CNPC in the world. No discovery was made in the Permit H in more than 30-year exploration by some international oil companies. As a Meso-Cenozoic intensively inversed rift basin under the influence of the Central African Shear Zone (CASZ), the Bongor Basin experienced three evolutionary stages, i.e., rifting stage in early Cretaceous, strong uplift and inversion stage in late Cretaceous and finally basin-forming stage in Cenozoic. The basin is composed of 4 major structural units, i.e., the northern slop,central depression,southern uplift and southern depression.The central depression consists of the eastern, central and westen sags, among which the central sag with fault in south and overlap in north is the predominant one. The basin is essentially characterized by inversion and strike-slip structures. The primary source-reservoir-caprock assemblage of the basin is located mainly in the lower Cretaceous with faulting and inversion as major pool-controlling factors. An enriched hydrocarbon zone was confined by combination of inversion structures and favorable sand-rich lithofacies.

In order to study the fluid flow behavior in hydrocyclone, the whole flow field of fluids in hydrocyclone with a bitangential inlet and twin cones was measured with the laser particle image velocimetry (PIV), then the Tecplot was utilized to display the flow field, extract the tagential axial and radial velocities, calculate the vorticity, and plot the locus of zero vertical velocity (LZVV). Distributional patterns of tangential and radial velocities in the swirl chamber of hydrocyclone as well as the axial velocity, local vorticity and locus of zero vertical velocity (LZVV) of fluids within the upper cone section under various flow conditions were investigated. The results show that in the swirl chamber, the tangential velocity of fluid is distributed in a shape of centrally symmetrical concave parabola, and its rotary momentum is mainly concentrated on the wall and at gas column, while the radial velocity shows an asymmetric “double-M-shaped” distribution with a velocity at the gas column bigger than that on the wall. In the upper cone section, the axial velocity of fluid has an irregular “M-shaped” distribution, inconsistent with the flow rate but fluctuating with its increase, the local vorticity of fluid shows an irregular “double-M-shaped” distribution with a absolute value of the negative vorticity getting larger near to the swirl chamber wall, the LZVV is somehow approximately like an irregular conical surface, and both the shape and the distributional locality of the LZVV are affected by the fluid flow rate within the bitangential inlet and by viscosity of the medium used.

The complicated fold-thrust belt is developed in the Kelasu structure zone of Kuqa Depression. The structural deformation of subsalt strata is more intensive and has the deformation features of inversion structure. According to the geologic section, the inversion structure of the Kelasu structure zone has the reactivation property of precursor normal fault and shortcut fault formed on the footwall. In the position far from the reactivated fault of the south part, the decollement of cover probably occurred. The Kelasu structure zone can be divided into three secondary belts including the inversion faulted anticline belt, wedge-like imbricate belt and thrust front belt. On the footwall of reactivated fault, the branch fault was developed in the west part of the Kelasu structure zone more than in the east part. In the latter back, the thrust and folding were generated on the hanging wall of reactivated fault. The horizontal compression and vertical shear of Southern Tianshan resulted in the basement-involved high-angle thrusts and the reactivation of some normal faults, which makes generation of inversion structure. In the inversion faulted anticline belt, the large-scale and plane structural traps with the thin superposition salt layers were developed, and natural gas easily disappeared in the superposition salt layers. In the wedge-like imbricate belt, the small-scale and large-attribution structural traps with the thick superposition salt layers were developed, which is favorable for preservation of natural gas.

Wolonghe Gas Field is the first gas field discovered in China and has the multiple source rocks,multiple reservoirs and multiple traps.According to the component and carbon isotopic compositions of gases from three main reservoirs including the Lower Triassic Jialingjiang Formation,the Middle Carboniferous Huanglong Formation and the Lower Permian,the origin of natural gas and the main source rocks were determined in combination with the distribution of source rocks.The gases in the Lower Triassic Jialingjiang Formation are mainly composed of coal-formed gases from the Upper Permian humic source rocks and a slight mixture of oil-type gases from Silurian sapropelic source rocks.The gases in the Middle Carboniferous Huanglong Formation are mixture of gases from Silurian sapropelic source rocks with different maturity.The gases in the Lower Permian are dominated by oil-type gases,which derived from Silurian source rocks mixed with a little gas from the Lower Permian carbonates.Besides,there are a lot of oil-cracked gases in Wolonghe Gas Field.Moreover,the main controlling factors of Wolonghe Gas Field include the high quality source rocks lying in the gas-generating center and surrounding area,the excellent reservoirs,traps related to the paleo-uplifts,and late-period accumulation.

A new method for the non-linear least square estimation was proposed on the basis of the characteristics of Casson rheological formula.It is unnecessary to artificially give an initial iteration value.The iteration process of this method can converge steadily to a unique minimum point in the domain of parameter and can not fall into the trap of the minimum point.This method requires a little storage and can converge rapidly.This is a globally optimized algorithm and can derive a rheological parameter estimation,showing superior statistic features including near unbiasedness of fitting residual error and almost least variance.The calculation cases,using a large amount of practical drilling fluid dada,indicate that the new method has smaller fitting variance,more similar mean value and more superior statistical feature of fitting residual error than the linear regression.This method can be used to determine the rheological parameter in Casson model of drilling fluid,optimize rheological model,adjust and evaluate the performance of drilling fluid.

The broad offshore is very rich in oil-gas resources in China. Amounts of oil and gas were discovered in this area during 40 years of exploration. However, owing to the limitation of technology, information and research extent, it has always been considered that all the basins in China offshore are similar in types and geologic conditions and classified as the Cenozoic rift basins on the continental margin. The analysis on a massive amount of seismic and drilling data shows that there are two depression belts in China offshore. The two depression belts are evidently different from each other in their tectonic situations, geothermal gradients, basin types, forming periods, sedimentary environments, petroleum geologic conditions and petroleum properties. The first depression belt containing Bohai Bay Basin, South Yellow Sea Basin, Taibei Depression, ZhuⅠ Depression, Zhu Ⅲ Depression and Beibuwan Basin is the lacustrine rift basin located on the continental crust and mainly generates oil. The second depression belt containing Zhedong Depression, Zhu Ⅱ Depression, Qiongdongnan Basin and Yinggehai Basin belongs to the marine depression basin located on the continent-to-ocean transitional crust and mainly generates gas. The first depression belt has already become a very important oil-producing area, and the second depression belt is expected to be a large gas-producing area in China offshore.

The common relative permeability curves weve divided into three types of type-Ⅰ,type-Ⅱand type-Ⅲ relative permeability curves.The investigation of 70 relative permeability curves shows that all relative permeability curves have the same characteristic.When any relative permeability curve was plotted in a semi-log graph paper,the relative permeability could be showed by logarithm coordinate,and the water saturation was showed by ordinary coordinate.When certain modification factors were introduced,a straight line could be achieved and defined as the relative permeability eigen curve.The relative permeability and water saturation fulfills linear equation.The three types of relative permeability curves have the same format of eigen curve.The relationship between connate water saturation and air permeability,the relationship between water saturation at residual oil point and air permeability,and that between oil phase relative permeability at connate water saturation point and air permeability were determined.Based on these relationships,relative permeability eigen curve method can be used to produce relative permeability curve for every grid block of reservoir numerical simulation and significantly improve the reservoir numerical simulation

The Changqing Oilfield Company has extensively and efficiently developed reservoirs with ultra-low permeability between 0.3mD and 1mD. Based on the practice of petroleum exploration and development in Ordos Basin, the tight oil herein refers to the oil that accumulates in oil shale or interbedded tight sandstone reservoirs adjacent to source rocks and with surface-air permeability less than 0.3mD. Generally, this accumulated oil has not yet experienced large-scale and long-distance migration, and thus its accumulation includes tight sandstone and tight shale oil reservoirs. The tight oil of Yanchang Formation mainly develops in a semi-deep to deep lake zone, typically in the oil shale and tight sandstone of Chang-7 interval and the tight sandstone of Chang-6 interval of the central lake. Tight oil in Ordos Basin is characterized by a wide distribution, superior conditions of source rocks, tight sandstone reservoirs, complex pore-throat structures, poor physical properties, high oil saturation, better oil properties and low pressure coefficient. Wide development of nano-sized pore-throat systems is one of the fundamental characteristics for the oil and gas continuous accumulation of tight oil reservoirs. Most of the connected pore-throat diameters of tight sandstone reservoirs in Yanchang Formation are greater than the critical pore-throat diameter, gratifying the need of oil and gas to migrate in tight reservoirs. Reservoirs of the tight oil in Yanchang Formation can be divided into 3 different types depending on the contact relationship between tight reservoirs and source rocks, i.e. compact massive sandstone reservoirs, sand-shale interbedded reservoirs and tight reservoirs in oil shale. Tight oil is widely distributed in Chang-6 and Chang-7 intervals of Yanchang Formation in Ordos Basin, and it is preliminarily forecasted that the total resources of tight oil in Ordos Basin are about 30×10⁸t, of which the shale oil resource in Chang-7 interval exceeds 10×10⁸t, while the tight sandstone oil resource in Chang-7 and Chang-6 intervals amounts to about 9×10⁸t and 11×10⁸t, respectively. Therefore, tight oil resources are the realistic oil replacement resources that can ensure Changqing Oilfield to achieve an annual output of 5000×10⁸tons of oil equivalent and a long term stability of oil production.

The study on the crust-derived abiogenic hydrocarbons was developed quickly in recent years at abroad.The forming mechanisms and geological and geochemical characteristics of crust-derived abiogenic hydrocarbons were summarized,and the possibility of forming reservoirs,the favorable zones and the correlative study prospect were analyzed.The results showed that the crust-derived abiogenic hydrocarbons existed indeed and also distributed widely.The foreground of research on them is broad,though many unknown fields still existed.As the studies go forward,the understanding to the abiogenic natural gas,especially to the crust-derived abiogenic hydrocarbons,will get a new step.

The primary migration mechanism of oil and gas in Fuyang oil layer showed that gas and oil migrated to Fuyang oil layer along the fault and fracture under the abnormal pressure in the source rocks.According to the acoustic logging data of hundreds of wells,the overpressure of K ₁qn ₁ mudstone under the most buried depth was resumed by using balancing depth method.The dynamic force and direction of primary migration of oil and gas were discussed.The ancient fluid potential from K ₁n ₁ to nowadays was resumed by using numerical simulation.The distribution characteristics of fluid potential and secondary migration direction of oil and gas at the critical time of K ₁m ₂ were analyzed.On the basis of the distribution of ancient fluid potential,the beneficial hydrocarbon regions in Fuyang oil layer were predicted by combining the characteristics of hydrocarbon-generation and hydrocarbon-expulsion,transforming system,and development of cap formation and trap.