Data always take the basal and key position in an oilfield enterprise's informationization. In the Changqing Oilfield, datarelated issues are becoming main bottlenecks restricting the value and benefits of information systems, as its informationization changes from centralized database construction to integrated application and big data analysis during the 13^th Five-Year Plan. The traditional data management mode is based on database and highlight the capitalized management of data by disciplines, making this mode inconvenient for the integration of multi-disciplinary applications. Data center construction and management mode in the era of digitalization is studied strategically according to the idea of life-cycle data management for hydrocarbon reservoirs. Thus, a data center mode of hydrocarbon reservoirs with data service and analysis application as the core, integration of business dominant, business flow and data flow, centralized management and on-line monitoring is proposed to ensure that the data is normalized. This mode can provide effective guarantee for resource sharing, collaborative research and comprehensive decision.

The first commercial tight oil field in continental facies in the world was discovered in the Upper Triassic Yanchang Formation of the Ordos Basin in central China. Different from other liquid hydrocarbons found in marine shale systems in North America, tight oil reservoirs in the Ordos Basin are lacustrine deposits where the tight oil is mainly preserved in tight sandstones in the middle-upper seventh member of the Yanchang Formation (Chang 7 Member) in a lacustrine basin, and characterized by overlapped sand bodies (20-70 m thick), tightness (with porosity of 6%-12%, permeability <0.3mD), high brittle mineral content (70%-80%), high crude oil saturation (60%-80%), high crude oil quality (in-place oil density of 0.70-0.75 g/cm³), low formation pressure (pressure coefficient between 0.6-0.8), low production (several tons to more than ten tons per well per day), and extensive and continuous distribution (3×10⁴km²). Based on the geological and drilling data of the tight oil in the Chang 7 Member of the Ordos Basin, and using the "sweet spots prediction method", this paper calculates that the in-place petroleum resources is 42.26×10⁸t, the average resource abundance is 15×10⁴t/km², and the distribution area is 2.9×10⁴km² in the Chang 7 Member. The discovery and overall development of the first continental tight oil field is of great importance for large-scale exploitation of lowquality tight oil resources in similar continental depression basins.

The occurrence, geochemistry,genesis and distribution of the natural gas were studied for analysis of the natural gas exploration fieldsin the Nanpu sag. The Nanpu sag is rich in oil and gas resources, where at present, the primary exploration target is oil. Oil and gas resources have been found in the Guantao, Minghuazhen, Dongying and Shahejie Formations, pure gas and condensate gas are mainly distributed in the 1^st and 2^nd Members of the Dongying Formation, and solution gas is distributed in all formations. The discovered natural gas is mostly wet gas with a small amount of dry gas, which are mostly distributed in the Beipu Structure, the Nanpu 1 Structure, the Nanpu 2 Structure and the Nanpu 5 Structure. The first type of the natural gas is transitional, second humic and third sapropelic. These three types of natural gas show stronger tendency of vertical migration, especially the transitional and the sapropelic gas. The important oil and gas exploration fields in this sag include:the natural gas accumulation of the overflowing gas from shallow-middle continental oil pools, and the near-source tight sandstone gas pools, lithologic gas pools or light oil and gas pools in the deep layers and the slope of the Nanpu sag.Shallow gas is mainly transitional and local gas is sapropelic. Deep gas includes sapropelic, humic and transitional type.

A shale gas system is mainly composed of clay mineral-rich shale and its remarkable characteristic is self-generating and selfpreserving. When the high-resolution scanning electron microscope (SEM) is used to analyze the micro pore structures and mineral compositions of shale, the surface of the samples shall be polished by means of argon ion to meet the requirements of sample preparation. The argon ion polishing can improve the quality of SEM images, but in the meantime, it deteriorates the authigenic forms of the minerals, increasing the difficulty of SEM mineral identification. In order to identify and analyze the mineral compositions of shale more intuitively, the SEM images and EDS (energy dispersive spectrum) characteristics of main minerals in the polished shale samples were summarized based on the analysis results of FIB-SEM (focused ion beam-scanning electron microscope) and X-ray EDS. Then, the corresponding chart was established. And by virtue of this chart, the mineral compositions of shale can be analyzed qualitatively and quantitatively. It is shown that the qualitative identification results are consistent with the EDS scanning results. The error between the mineral compositions calculated by means of the software after the mineral division and extraction and the X-ray diffraction experiment results is larger. And it is recommended to optimize the quantitative mineral calculation method based on image analysis.

In order to realize the exploration and development aim of "high efficiency with fewer wells" in Puguang gas field, it is of great significance to search for the good-quality reservoir development zones. In Puguang gas field, the platform margin shoal-platform front ramp of Feixianguan Formation marine carbonates are characterized by shallow sedimentary water and strong evaporation. In this environment, the reservoir combination of oolitic dolomite in T₁f₁₊₂ platform margin shoal and muddy-micritic dolomite in T₁f₃ evaporative platform lagoon is developed, and the reservoir space is mainly in the form of secondary pores and less fractures and vugs. The T₁f₁₊₂ oolitic dolomite is characterized advantageously by large pore, medium-coarse throat, moderate-high porosity and high permeability, but the T₁f₃ muddymicritic dolomite presents the characteristics of poor reservoirs, e.g. micro pore, tiny throat, low porosity and low permeability. It is indicated that the quality of reservoir development is mainly controlled by the joint effect of sedimentation, diagenesis and tectogenesis. Among them, sedimentation is the foundation, thus the platform margin shoal is the most favorable reservoir facies. Diagenesis is the key effect, and a large amount of secondary solution pores are formed due to the dolomitization and the stacked dissolution of two periods of hydrocarbon generation, thus the physical properties of the reservoirs are improved greatly. The formation and evolution of source rocks reservoirs are controlled by the early tectonic uplift, the dominant oil and gas migration pathways are dominated by the late NE-striking fault system, and the seepage channels are acted by fractures and faults. Consequently, potential good-quality reservoir development areas are formed.

The fractured tight sandstone reservoir in the Kuqa foreland basin is ultra-deep with ultra-high pressure. To obtain economic productivity from the reservoir, it is essential to stimulate the potential of natural fractures with appropriate strategy. Based on the fine fracture evaluation and logging interpretation, the mechanical activity of natural fractures is studied, and accordingly the reservoir stimulation treatment is optimized. Through numerical simulation and theoretical analysis, it is found that the effectiveness of natural fractures, in addition to the dip angle and dip direction, has a significant effect on the mechanical activity of fractures during the treatment, and the calculation method of the shear activation pressure of the fracture is given. The effectiveness of fractures is evaluated comprehensively in respect of mud loss events, quantitative analysis of imaging logging parameters, core analysis, R/S scale-variable analysis and so on, and the classification criteria for such reservoir fractures is put forward. According to the analysis on mechanical activity of natural fractures, the customized stimulation strategies are proposed. To be specific, different fracturing strategies, such as volumetric acid fracturing, fracture network fracturing and large-scale sand fracturing, can be employed for three types of reservoirs with different fracture development features. In this way, the reservoir stimulation scheme is improved. The improved scheme has been satisfactorily applied in the Bozi block in the western Kuqa basin. As a result, the actual production is significantly higher compared with adjacent wells. This scheme facilitates theoretically and technically the effective production of nearly 100 billion cubic meters of reserves in the block.

Seven sags in the deep water area of the Pearl River Mouth Basin reside in two first-order structural units, i.e. Zhu Ⅱ depression and Zhu IV depression. The two depressions commonly underwent five tectonic evolution stages, including initial rifting, sustained rifting, early post-rifting subsidence, late post-rifting subsidence, and neotectonic movement. They are significantly different in tectonic characteristics and sedimentary filling in different stages or during the same stage, thereby leading to different hydrocarbon geological conditions and exploration potentials. Three types of source rocks (i.e. lacustrine mudstone, coal-measure and terrigenous marine mudstone) are mainly developed in the Zhu Ⅱ depression. Two types of source rocks (i.e. coal-measure and terrigenous marine mudstone) are mainly developed in the Zhu IV depression, revealing hydrocarbon accumulation conditions inferior to the Zhu Ⅱ depression. During the first three stages (i.e. initial rifting, sustained rifting, early post-rifting subsidence, and late post-rifting subsidence), multi-stage delta and channel-deep water fan sand bodies were developed; the sand bodies in the Zhu Ⅱ depression are diverse and wide, showing better accumulation capacity. Two sets of plays of late postrifting subsidence and sustained rifting are developed in both depressions. By comparing the play elements, it is concluded that the exploration potential of the Zhu Ⅱ depression is better than that of the Zhu IV depression.

Shale, as one type of unconventional reservoir, is characterized by low porosity and low permeability. To improve its deliverability, large-scale hydraulic fracturing is required. Brittleness of the rock must be taken into consideration during the reservoir fracturing. The shale of the lower third Member of Shahejie Formation (lower Sha 3 Member or lower Es₃) in the Luojia area of the Zhanhua sag is abundant with oil and gas resources. Its brittleness was investigated in respect of mineral composition, geophysical logging and triaxial stress test. The results show that, in respect of mineral composition, the brittleness index of the lower Es₃ shale is 56.3%, suggesting that complex fracture system may easily form after fracturing; in respect of geophysical logging, the lower Es₃ shale exhibits high Young's modulus and low Poisson's ratio, and its brittleness index is over 40%, which also prove that the shale is very brittle; in respect of triaxial stress test, the triaxial compressive stress-strain curves of the core samples present all brittle failure, which once again shows high brittleness of the shale. Accordingly, it can be concluded that the brittleness of the lower Es 3 shale in the Luojia area is good, revealing certain fracturability.

To improve comprehensive evaluation of coalbed methane (CBM) resources in Hancheng mining area, the paper studied the geological conditions, coal reservoirs and gas-bearing properties of coal seams in Hancheng mining area based on the original data obtained from CBM wells distributed in the whole area, and established a calculation model using stepwise regression method, based on which calculated coalbed methane resources. The study results show that, in this area:(1) primary coal-bearing strata are the Permian Shanxi Formation and the Taiyuan Formation where No.3, No.5 and No.11 coal seams are primary and distributed stably, and show high vitrinite content, high metamorphism of coal, and great potential of adsorbed coalbed methane; (2) main controlling factors on gas content in the coal seams are buried depth, structure, hydrogeology, vitrinite reflectance, ash content, macerals and caprock; (3) both gas content and gas saturation are high, but the permeability of the coal seams are relatively low (<0.5 mD), which should be stimulated in later coal development. The prediction of coalbed methane resources in this area shows that the total CBM resource is 858.25×10⁸m³, and the resource abundance is 0.93×10⁸m³/km², of which, the coalbed methane resource in the coalbeds shallower than 1200 m is 672.32×10⁸m³, and the resource abundance is 1.08×10⁸m³/km².

Systematic studies have been carried out on the conditions and characteristics of the Paleogene far-source hydrocarbon accumulation and the exploration strategy in the Melut Basin, Central Africa, and state that the strong differentiation of rifting and sagging is the main controlling factor on the development of the sandstone-rich formations and far-source reservoirs.The delta front facies in the upper Paleogene Yabus Formation is developed with shallow buried depth and good reservoir properties, and favorable for forming high-productivity reservoirs, so it is the ideal target for discovering commercial lithologic reservoirs in the Melut Basin. The oil source condition is the key factor on the Paleogene far-source hydrocarbon accumulation,and the structural-lithologic traps controlled by oil-migrating faults are favorable traps.Based on the study on oil-water contact and hydrocarbon detection, discovered structural traps with oil-water contacts over over-flowing points were selected as initial targets for exploring far-source lithologic and structural-lithologic traps. This may reduce exploration risk and increase drilling success rate. This paper proposes favorable far-source lithologic reservoirs and their controlling factors, accumulation characteristics and exploration technology, expands the exploration field and provides technical support for the exploration of the Paleogene far-source lithologic and structural-lithologic traps in the developed northern exploration block in the Melut Basin.

In reflection seismic exploration, multiple waves are common and noises and seriously affect effective signals. Multiple waves can reduce the S/N ratio of seismic data and reduce the fidelity and reliability of seismic imaging. In deep Junggar Basin, the Jurassic coal layer overlying on the Carboniferous System is an interface with strong acoustic impedance, and the multiple waves reflected by the coal layer seriously affect the imaging effect inside the Carboniferous System; therefore, suppression of the multiple waves is very important for image processing in deep Junggar Basin. This paper identifies multiple waves based on theoretical model and field data, suppresses multiple waves by filtering method, and evaluates the suppression effect with quantitative indicators. This can provide guidance for selecting multiple wave suppression methods and improve the imaging effect of the Carboniferous System.

The statistical relationship between element contents and reservoir quality suggests that aluminum and vanadium can be used to measure reservoir quality, and the mechanism was analyzed. To make it a valuable reservoir prediction tool, following the principle that combines the mechanism with seismic inversion methods, several experimental researches were conducted on primary seismic inversion methods, and finally a reservoir quality evaluation method was developed based on cuttings analysis data. Specifically, frequency-divided inversion was employed to map the spatial variation of favorable reservoirs based on cuttings analysis data. The method is of great importance to pre-drilling research. In addition, hardly affected by radioactive elements, it is useful for re-examination on old well data, especially in early exploration without enough drilled wells. For field application of this method, the resolution and how to filter data are discussed in this paper. This technology has been applied in a HPHT gas field in the Yinggehai basin and achieved a great success:the TVD prediction error of high quality reservoirs in 6 directional wells and 1 horizontal well is less than 6m(4ms), which meets the ODP adjustment precision while drilling, and realizes multi-disciplinary dynamic integration of mud logging, experiment, geology and geophysics.

OBC (ocean bottom cable) seismic survey as the primary method for seismic data acquisition in shallow water and transitional regions plays a significant role in tidal regions. OBC experiences involving diverse and flexible variable recording geometries in seismic survey in the tidal zones of the Bohai Bay have been frequently used in places where conventional streamers are not available. However, complicated marine conditions and varying ocean bottom topography often bring a lot of challenges to field OBC operation. This paper introduces OBC seismic survey by focusing on three special conditions:how to ensure the accuracy of cable layout and secondary positioning in ocean trenches, how to improve seismic data in complex obstacle area, and how to improve the coupling between geophones and seabed under the conditions of hard ocean bottom and stronger tidal activity. Cases are used to verify these conclusions and experience are summarized. Finally, this paper provides solutions and QC suggestions on OBC operation in similar survey areas.

Aerated nitrogen drilling is an important technical method for discovering and protecting oil and gas reservoirs, controlling mud loss in fractured reservoirs, and improving ROP. Using experimental data and calculation demonstration, the fluid patterns of gas-liquid two-phase flow in wellbore annulus and drill string while drilling were analyzed, the wellbore fluid flowing model and numerical solution during aerated drilling were established, and the gas-liquid flowing parameter design chart for conventional wellbore structures was developed and used the aerated nitrogen drilling test in Well Baiquan 1 in the Junggar Basin. In the field test, the safe density window of the drilling fluid was selected, and nitrogen injection parameters and underbalanced drilling equipment were designed according to the leakage and collapse pressures of the Permian fractured reservoirs. The successful application of this method in Well Baiquan-1 has fully proved that the aerated nitrogen drilling technology has wide formation adaptability, larger pressure control range, and effective reduction of lost circulation in fractured reservoirs, thus it is beneficial to reservoir exploration and discovery. Moreover, the new design chart can completely satisfy the requirements for engineering design and field operation in aerated nitrogen drilling in conventional wellbores.