After the discovery of Kela-2 gas field, exploration for oil and gas hit bottom in Kuqa Foreland Thrust Belt. Except for Kela-2 gas reservoir, no new boreable traps were discovered. To explore deep oil and gas fields was also faced with such difficulties as geologic complexity, difficult trapping, and lag in technology. To solve the difficulties above, first is to rediscover Kuqa Foreland Thrust Belt, be confident in exploration, and identify main exploration areas; second is to develop seismic and geologic integration technology such as wide line combination, 3D acquisition and processing, modeling of the structure relevant to salt, and phase velocity field building, to discover Keshen-Dabei zone, and to discover and fulfill some drillable traps; third is to intensify development of drilling technology and fulfill efficient and rapid drilling in subsalt ultra-deep, high-pressure and high-temperature gas reservoir. In the past ten years, the exploration depth of Kelasu structural belt was increased from 4000m to 8000m, several large gas fields including Keshen 2 and Bozi 1 gas fields were discovered, and one trillion cubic meters of natural gas resources were gradually identified in Keshen zone. Breakthroughs in exploration of large and deep subsalt gas fields here benefits from innovation of geologic recognition, improvement of exploration techniques, and perseverant exploration practice.

Transfer structure developed in different types of basin. The inherence of the structure is various deformation of basins under regional stress field. It was always formed with several faults or folds in strike directions and displayed the transformation between each other. Because of the complex feature of the structure, it is difficult to be described. Using 3D seismic data could not only enhance the quality of the profiles, but also provide the 3D information about the geology body which makes the research on transfer structure better. Based on up-to-date 3D seismic data, research is conducted on the 3D geometry and interconversion about KL1 and KL2 structure in Kuqa foreland thrust system. Results show that: (1) KL1 and KL2 are pop-up structures formed by two opposite inclination thrust faults and an anticline between them. (2) There are complex structures in this belt which perform as differential joint of the core and the limb of the anticline under the effection of transpression. (3) Quantitative analysis of fault activity shows that KL1 and KL2 have experienced initiative low anticline stage, pop-up structure stage, lateral growth stage and strike-slip transfer stage. (4) The preservation condition which is influenced by fault activities is different in KL1 and KL2. KL2 structure is rich in gas. The petroliferous property of KL1 structure is poor.

Guided by sequence stratigraphy and based on seismic, drilling and well logging data in Hulihai sag of Qianjiadian Depression, analyzing the background of structural evolution and sedimentary environment, climate condition, Cretaceous sequence can be subdivided into one first-order sequence, two second-order sequence, six third-order sequence. SⅢ1 (Lower Cretaceous Jiufotang Formation) develops completely, which is composed of lowstand, transgressive and highstand system tracts. According to the characteristics of sequence development and based on division and comparison of sequence formation units, sedimentary types and system are studied. It is concluded that S Ⅲ 1 in Hulihai sag features in near and more provenances, rapid subsidence and rapid deposition. The highstand system of SⅢ1 develops nearshore subaqueous fans in the west steep slope belt, and fan delta in the east gentle belt. Shore-shallow lacustrine and deep lacustrine facies are recognized in the central sag; turbidite fan is distributed in some area. The sequence, which is between the transgressive system tract of the second and the third-order sequence, has the best source rocks and sealing conditions as well as various favorable reservoirs. So it is the most favorable target for obtaining discoveries in Hulihai sag.

Based on regional geological background, it is believed that the basal conglomerate in North-Kunlun Faults Zone is weathering eluvium. Petrographic analysis shows that the bedrock in the zone is monzogranite. Above this is semi-weathered crust, which is about 0.5m deep. Here develops rock breaking fracture. Above the semi-weathered crust is the basal conglomerate, which is 30~60m deep. This is the main hydrocarbon reservoir assemblage in North-Kunlun Faults Zone. Conventional porosity and permeability analysis shows that the average porosity value is 12.37% and the average permeability value is 69.87mD, belonging to low-porosity and mid-permeability reservoir. Reservoir pore is dominated by secondary pore including particle breaking fracture, particle dissolved pore, and intergranular dissolved pore, etc. Rock in the reservoir is unconsolidated for its weak diagenesis and big grain size, so conventional porosity and permeability analysis could not actually reflect rock property. Comparison shows that the porosity determined by conventional analysis is 25% higher than using kerosene method, and the permeability determined by conventional analysis is 80% higher than using NMR method. Therefore, using rational testing method to get reservoir property targeted at the basal conglomerate becomes more and more important to guide exploration and development in studied area.

Erlian Basin in Huabei Oilfield features in polycyclic sequence, multiple sets of source-reservoir-cap rock assemblages, diversified sandstone traps, and multi-period accumulation. So how to improve research and prediction on sand-shale interbed efficiently becomes an important issue for conducting reservoir prediction research. This paper discusses the geophysics response characteristics of “strong amplitude and high continuity”, which increases the multiplicity of reservoir prediction, and puts forward corresponding countermeasures. It is pointed out that the sand-shale interbed research area focuses on improving resolution, under the constraint of isochronous stratigraphic framework, combining with forward modeling techniques, proceeding from theoretic model, and using the method integrating frequency broadening, frequency dividing, and seismic inversion to conduct comprehensive research. Application shows that countermeasures have brought about good results, providing important theoretic basis and technical support for well deployment and reserves submission in Erlian Basin.

During the seismic prospecting in complex mountainous areas, complex surface leads to more shot point and geophone station offset. So it is very difficult to control field quality precisely with conventional methods. This paper mainly elaborates a new set of quality control flow using existing software---first break fitting, thus completing the quality control procedure and accomplishing quality control of shot point location in the fields. Due to the complexity of the areas, signal-to-noise ratio and resolution are relatively low, and data vary a lot, so it gets more difficult for processing. During the process, some key field processing techniques are adopted, i.e. phase adjustment, denoising, amplitude recovery, energy compensation, velocity optimization, residual static correction, and poststack random noise attenuation, improving the signal-to-noise ratio and resolution. Therefore, good results are obtained

The muddy limestone compact hydrocarbon reservoir in Shulu sag is one of the important exploration areas in Huabei Oilfield because of its abundant remaining resources. The matrix features in small pore throat, weak connectedness and strong anisotropism. As the development of fractures is a decisive factor to hinder the pay bed from forming reservoirs, precisely forecasting the muddy limestone area has become a key emphasis in work. Techniques of pseudo-acoustic wave inversion optimization, reservoir parameter inversion, stress field simulation and attribute azimuthal anisotropy are used to accurately depict the spatial pattern, shale content, strain-stress characteristics and azimuthal anisotropy of the muddy limestone, based on which indicates the development area of muddy limestone fracture. The forecast finding provides important reference for the ST-1H well geometric arrangement and track design. The drilling result proved the accuracy of the forecast result and feasibility of the forecast method.

Pyroclastic rock reservoir is very thin in the second member of Yingcheng Formation in Lower Cretaceous of Wukeshu area in Yingtai Rift, Songliao Basin. Longitudinal wave impedance difference is small, serious and range overlay routine impedance inversion method is difficult to identify reservoir. Based on seismic data frequency broadening, stacked seismic statistical inversion method is used and solves this problem effectively. The dominant frequency band of the target layer is broadened, energy is increased, and the main frequency is increased significantly, by the use of deep frequency broadening technology. Poststack geostatistics takes into account the vertical resolution of seismic data and the lateral resolution of logging data. By taking the poststack constrained sparse spike inversion of the wave impedance of the body as hard constraints on data, the relationship between impedance and reservoir parameters is established. The effective reservoir distribution obtained from inversion and the effective reservoir displayed by drilling reveals high degree of agreement, which could reflect the change in reservoir properties. Joint research on seismic data processing and seismic data inversion method could reach better result for solving thin reservoir spatial distribution characteristics.

As the accuracy of seismic data acquisition is getting higher for oilfield exploration and development, the accuracy of near-surface structure is particularly important. To improve accuracy of seismic data acquisition, first is to get accurate surface data, looking for the best lithology shooting. This will improve the quality of seismic data considerably. In the course of study, test, analysis and summary are conducted on many survey methods for surface structure relying on the Shinan-Haojia seismic exploration project, developing the layered technology of speed, detection technology of lithology and layered technology of geotechnical physical parameters, etc. Test shows that selecting one or more appropriate methods for near-surface survey and making full use of their advantages could get the depth, speed and lithologic data for low velocity layer, based on the use of different methods and joint explanation, providing evidence for selecting shooting and receiving parameters and offering accurate data for static correction of seismic data.

Comprehensive analysis of pre-salt stratigraphic sequence, thermal history and trap evolution of Lula Oilfield (formerly known as Tupi Oilfield) in Santos Basin, Brazil, shows that the source rock of the oilfield is lacustrine shale of middle-upper rift sequence; its reservoir rock is carbonate of sag sequence; and its trap type is a lithologic-structural combination trap controlled by horsts formatting during Neocomian- Barremian rift stage, that trap evolution of Lula Oilfield experienced six stags, i.e. the early rift, middle rift and late rift stages of Neocomian- Barremian, the sag stage of early Aptian, evaporite stage of late Aptian and the pool formation stag from Albian to now, and that its accumulation feature presents subsalt deeper reservoir, lately gathering and medium mature of source rock. It is concluded that the very thick salt layer (~2000m) effect in distribution and high heat conductivity greatly delayed thermal evolution degree of pre-salt source rocks, and expanded the hydrocarbon exploration depth for the pre-salt section. In addition, the oil-gas accumulation zone of horst-stratum becomes a new exploratory frontier for the whole pre-salt sections, not only in Santos, but also throughout the eastern Brazilian offshore basins

Block 3 in Iran is the first oil exploration and development project of CNPC at Buy-Back contract. An oil discovery was got through 6 years exploration and appraisal in the block, which was evaluated and concluded non-commercial at Buy-Back contract, so the project was abandoned. Some geological knowledge, exploration experience and failure reason were summarized in the paper. First, exploration in block 3 indicates the geological complexity of the Middle East. Seismic acquisition and image are difficult, and the distribution of effective reservoir is controlled by fracture distributing in low porosity limestone deposit in bathyal facies in the block. Both of these need special exploration techniques and methods. At the same time, it is realized that the reservoirs of low porosity limestone with fractures may be important exploration field in the future of the Middle-East. Second, the affection of items of Buy-Back contract to the project is analyzed. It indicates the definition of commercial field in the Buy-Back contract is the key factor, and inaccurate cost estimation is another factor to the failure of the project. At last, some experiences are summed up further in the operation and execution of the project