This paper draws inspiration from analyzing the exploration progress in mid-small sized peripheral basins in recent years: firstly, the exploration results obtained have exceeded what expected, and peripheral basins are expected to turn into tangible domains for increasing reserves; secondly, deeply trapped petroleum generative sags are the most favorable exploration areas; thirdly, whether to discover large and medium sized oil and gas fields is critical to realize exploration peak and sustainable development; fourthly, technological progress assures the achievement of exploration breakthroughs importantly. On the basis of correlation of the maximum reservoir size and the resource abundance and scale of 21 sags of 8 mid-small sized basins with higher exploration degree, this paper sets the evaluating selection criteria of peripheral basins, carries on evaluating selection and exploration potential analysis of PetroChina's 21 peripheral basins, and confirms 6 Class-I basins and 8 Class-II basins with broad exploration prospect. On that basis, this paper conducts study on development strategy of mid-small sized peripheral basins, and proposes that exploration turn into deeply trapped sags from high structures at four levels.

Thought and technology innovations are like the wings of a bird and wheels of a car. As degree of exploration gets higher and exploration gets more difficult, new achievements will be made in exploration of old petroliferous districts, and big breakthroughs will be made in new districts, by emancipating the mind, deepening geologic cognition, transforming thought, improving work precision, and applying new practicable exploration techniques. This paper summarizes the exploration work SINOPEC has been launching in Junggar Basin since 2001, the exploration ideas and geologic cognition SINOPEC has formed, and what SINOPEC has learned from experience, with an aim to deepen geologic cognition of the basin and adjust ideas through academic exchange, and to accelerate oil and gas exploration and development.

Taking Permian and Triassic reservoirs in Junggar Basin as an example, this paper firstly points out the petrologic characteristics of low pressure, low permeability, low saturation and high gas content make the reservoir vulnerable to compaction, yet the porosity tends to get improved below 4000m. Secondly, this paper analyses the factors affecting porosity, and deems that organic acid denudation and oil cut are the main effect factors improving reservoir quality. Reservoir denudation is prevalent under SEM survey. Acidic leaching simulation experiment confirms the existence of denudation minerals, and proves that denudation has great potential for improving the quality of reservoir porosity. It probes into how reservoir porosity is affected by oil-bearing characteristics, and shows that the porosity of oil-bearing sandstone is obviously better than non oil-bearing sandstone on the same condition. Mass data analysis confirms oil cut could effectively control the growth of diagenetic authigenic minerals and reduce the content, and thereby maintain effective pore in deep-buried reservoir.

Due to the high heterogeneity of fracture-cavity type carbonate reservoir, it is difficult to build reservoir model effectively with the traditional method of combining well data and geological layers. However, the conventional seismic attributes extraction means can not be integrated with log data to describe reservoir quantitatively. In order to apply seismic data to quantitative reservoir modeling research, in this study, the correlation between log P-wave impedance and total porosity is built on the basis of clear correspondence between various seismic reflections and fine interpretation of the top horizon of reservoir, and geostatistical inversion is carried out to calculatemulti-high-resolution P-wave impedance volume. Using the statistical relationship between P-wave impedance and total porosity to co-simulate can calculate multi-equivalent porosity volume. Equivalent porosity volume integrates the scale of log and seismic information very well, and can be used for the quantitative description study of fracture-cavity type carbonate reservoir spacial heterogeneity. This study provides ideas and methods for quantitative reservoir description in fracture-cavity carbonate reservoirs with seismic inversion technique.

Zhenjing block of Ordos Basin, located in the south of Tianhuan syncline, is the principal hydrocarbon area of SINOPEC. There is a good space-time correlation among lithologic traps formation time, hydrocarbon generation time and accumulation time in the area, which is favorable for lithologic reservoir formation. The dynamic accumulation process is mainly controlled by the tectonic evolution and trap evolution: Chang 8 layer was reversed from northeast sloping to southwest sloping. Reservoirs are subjected to adjustment, continuing migration from convex parts of sand body to the tectonic high points. According to trap evolution of pre-accumulation to current period, favorable traps are formed from Chang 8 layer, which is favorable for reserving and yielding oil and gas.

Chuxiong Basin is located at the southwest margin of Yangtze tectonic plate. The Red River fracture controls the southwest boundary of the Basin with a high angle transition from NWW in the southeast to NW of study area, then NWW again in the Qinghai-Tibet Plateau. Maximum principal stress orientation in the Basin has changed several times since Mesozoic from nearly SN to EW, the Red River fault has undergone left-lateral or rightlateral strike-slip movement, accompanied by internal block rotating, due to the continuous NNE compression stress generated by the Indian Plate movement from southwest to northeast, the existence of Jinsha River-Red River fracture, and the westward compression stress transferred from the Marginal-pacific tectonic domain east of China. The strike-slip movement and stress transfer of Red River fracture also cushion the extrusion deformation of the Basin. Base on the seismic interpretation of the whole Basin, in view of the complex depositional-tectonic characteristics of the Basin, this paper selects two regional seismic profiles of SN and EW orientations for tectonic evolution analysis with balanced-section technique, then analyzes the basement formation of the Basin, the dynamic driving mechanism and its derivative tectonic evolution, depositional migration, source-reservoir-cap rock assemblages, fault activities, igneous rock distribution and the condition of hydrocarbon accumulation since Late Triassic, on the basis of the regional tectonic background. It is concluded that: ① The maximum principal stress orientations have changed several times in the Basin since the Mesozoic Era, and controls the linkage effects among tectonic migration, distribution and thickness of source-reservoir-cap rock assemblages, fault features and hydrocarbon accumulation; ② The distribution of igneous rocks relates closely to the distribution of basement fractures, so much attention should be paid to the recognition of large basement faults in future exploration; ③ Source rock in western depressions of the Basin features in wide distribution, high thickness, thick cap rock, high shale content, and good sealing property, which is favorable for hydrocarbon generation and preservation. In particular, the long-term successive evolution structural belts or traps with SN-NW trends would be the prospecting domains of priority for further exploration

This paper runs a numerical simulation of the history of burial, thermal evolution and hydrocarbon generation in Funing Formation, and analyzes lithofacies features and homogeneous temperature of fluid inclusions, based on previous study. The results show that hydrocarbon source rock in Funing Formation experienced continual subsidence period, lifting period and resubsidence period in turn. Hydrocarbon was generated from the late Paleocene Funing Formation to the late Eocene Sanduo Formation, and continuously charged and accumulated at Eocene Sanduo Formation. The infill injection of the deep concave zone occurred earlier than that of the north slope. It could be judged that the Sanduo period was the main hydrocarbon accumulation period of Gaoyou Sag. The main hydrocarbon accumulation period matches with the hydrocarbon generation and exclusion period and the trap formation period, which is favorable for hydrocarbon accumulation in the area

Differential deformation occurs in Meso-Cenozoic in northern side of East Qinling-Dabie orogenic belt due to imbalanced intercontinental orogeny and multiple tectonic superimposition and composition. The establishment of four typical petrofabric profiles demonstrates that fabrics are symmetrical orthorhombically or triclinically, and the southern part of each profile develops small circle girdle. The petrofabric features show that all samples undergo approximately horizontal NE-SW and NW-SE compression of two periods. The NE-SW compression in the west of Shangcheng- Huangchuan is the primary, but the intensity of compressions of two directions is similar in the east, and the southern Xixia-Yichuan profile undergoes intense uplift vertically. Intense overthrust tectonics in Indosinian and Middle Yanshanian taking Shangcheng-Huangchuan as an intermediate accommodation occurs temporal-spatial migration from east to west. Moreover, lateral fault accommodation during imbalanced deformation, and Neogene Tanlu fracturing are all fundamental causes of Meso-Cenozoic differential deformation in northern side of East Qinling-Dabie orogenic belt.

Hydrocarbon accumulation system is known as a unified complex capable of hydrocarbon accumulation under favorable geologic environment, which consists of hydrocarbon generation, reservoiring, capping, transportation, trapping, preservation and other key elements. It takes the accumulation unit as a closed, complex, relatively independent and open system, with features of integrity, hierarchy, relevance, openness, dynamics and comparability. The study of accumulation system should be guided by systematic scientific ideas, highlight integrity, probe into the accumulation factors qualitatively and quantitatively, find out main controlling factor, analyze the effect of environmental factor on the system, and finally determine the accumulation function integrates by considering all the factors mentioned above.

During the oil and gas exploration in subsalt structures of Kuqa Depression, the time section occurs distortion and forms pseudo-structure, because of the overlying strata structural morphology and velocity structure. The pseudo-structure differs a lot from underground actual structure. The variable velocity mapping includes the establishment of structure modeling and velocity field, but the velocity field accuracy affects the accuracy of trap identification.Avelocity field, containing log information, seismic information, sedimentary facies information, structure information and stress information, etc., could better reflect the longitudinal and lateral variation of formation velocity, with its high accuracy. It offers an accurate velocity model for variable velocity mapping, corrects distortion of the time section effectively, and thus improves the accuracy of trap identification

There are different interference source during the acquisition of offshore seismic data. Some is generated naturally, while the other is formed due to the outside disturbance, such as the disturbance from wind wave and current, disturbance from obstacles on the seafloor, disturbance from fishing, mechanical disturbance, and the disturbance from equipment used during the process. While analyzing the interference source during the process, this paper elaborates and categorizes the features and manifestation of interference wave on single shot or original stack profile, spreading out almost all the features of noise during offshore seismic data acquisition. In view of the features and manifestation of interference wave on single shot or original stack profile, this paper further illustrates the methods for identifying the interference wave during field acquisition or data processing in the lab, and summarizes the harm of interference and noise to seismic data.

In view of the insufficiency of former velocity analysis, this paper proposes the method of velocity analysis under the shaft: to carry on P-wave velocity analysis and NMO correction under the shaft based on the time-distance equation of offset distance and the VSP reflection time, as first break time of down-going P-wave is known. This article uses digital NMO correction method similar to surface seismic. Because the VSP ray path is asymmetrical, this paper studies and summarizes the method of calculating the position of spot in pressure wave after calculating the position of reflection spot, obtains common-reflection point-gather on binning, then carries on NMO correction, stacks with changed fold number. The authors process the vertical well Walk-away VSP P-wave record and the practical data, verifying the validity of this method and the ability to solve practical problems

Petrobras discovered three super giant oil and gas fields successively in subsalt sequence of deepwater basins in Santos, Brazil from 2007 to 2008. This paper analyzes the structural evolution and sedimentary filling features, fundamental petrogeologic conditions and subsalt hydrocarbon accumulation features, points out the subsalt series of strata in Campos Basin, Kwanza Basin in transatlantic South Africa and Lower Congo Basin, which are of the same basin in terms of depositional period. They have undergone the same tectonic evolution of passive continental marginal basins. Through analogous research, it is believed that these basins have similar petrogeologic conditions and accumulation features, of which subsalt strata have broad prospect for exploration and they will be important strategic oil/gas strategic zones in the future

This paper introduces the principle of the analytic hierarchy process (AHP) method and its application, and applies it to selection of oil shale target areas in China. During the process, the evaluation model and index system of oil shale area are established, the statistical weight of all indexes is identified, and the sum weight of each target area is acquired. Study indicates that the most important factor affecting oil shale area selection is geological parameters and resource conditions. And the key properties are oil saturation, burial depth and the amount of shale oil resources. By evaluating 11 oil shale target areas in China, it could be inferred that Heilongjiang Linkou oil shale is the best exploration area with the highest score, followed by Yanji Black Hill and Jilin Nongan.