Oil and gas resources are abundant in China. Although the exploration extent of themain petroliferous basins is high after long time exploration, the amount of remained oil and gas resources is still large, and it has the resource base for further development. After oil and gas exploration in tens of years,the preservation conditions of remained oil resources become worse￡?and the proportion of lowquality resourceswas augmented,the remained oil and gas resources in subtle oil and gas reservoirs is enlarged￡?and oil and gas exploration is getting more difficult. Oil and gas exploration field in China will be broad in the future, not only has four big realistic exploration fields, include the fine exploration in mature basin, the litho-stratigraphic reservoirs, the foreland and the lower-medium combination of superimposed basin, but also has some new exploration fields like Qinghai and Tibet, the south of the South China Sea, the marine carbonate rocks and "low-quality" resources.

Nantianshan orogenic belt and Tabei foreland basin is a pair of structural unit with conjugated and positive-negative dependence on each other, which can be divided into six structural units, including Laerdun deep thrusting zone resulted from basement engulfing, Haerkeshan fold thrusting zone, Kula front imbricate thrusting zone, Baicheng-Yangxia foredeep depression zone, Tabei foreland slope zone and Tazhong front uplift. The evolvement of Nantianshan orogenic belt and Tabei foreland basin controlled together the sedimentary characteristics, deformation feature and structural styles of Tabei foreland basin.Oil and gas resources is rich in Tabei foreland basin, which has favorable reservoir-forming conditions. The distribution of oil and gas ismainly dominated by petroleum system and regional cover. There are four structural zones with oil-gas enrichment, which include Kelasu structural zone, Yiqikelike structural zone, Qiulitage structural zone and Luntai fault-uplift zone, where Kale-2 ultra-large gasfield and other several oil and gas fields are discovered, and the added large oil and gas fields will be discovered.

Mesozoic-Cenozoic foreland thrusting belts occurred in Kuqa and in the southern margin of Junggar Basin, distributed in both north and south sides of Tianshan orogenic belt, whose formation and evolution have heavily affected and controlled the basins distribution, basement property, the scale of sedimentary cover and texture feature of whole basin and late destroying distributed in its both sides. In the process of same one regional stress field, the tectonic evolution and oil and gas geologic condition of Kuqa foreland thrusting belt and the southern margin of Junggar Basin all show much similar characteristics, both of them developed multi-set mature source rocks, and formed multi-set high-quality reservoir-cover combinations, and developed various traps. Because the relation among source rock, reservoir and cover is well matched, providing the material basement for forming large oil and gas fields

Marine paleo-uplift is referred to as the important field of oil and gas enrichment for medium-lower combination in Chinese superimposed basin, which can be divided into four types: inheriting type, sediment-control type (stratigraphic pinch out and reef beach in the margin of platform), finalized shape in later stage (fault uplifting and extrusion folding), reconstructing type in later stage (faultblock and monoclinal type). Based on the difference between the texture feature and reservoir-forming feature of oil and gas of marine paleo-uplift, four types of reservoir-forming combinations in paleo-uplift are shown as following: in vertical, the reservoir-forming combinations consist of the top, crust of weathering and inner episode ones; in plane, the reservoir-forming combinations include the core of paleo-uplift, upper slope and down slope and deep depressing. The research results indicate that the oil and gas distribution ofmarine paleouplift is featured by complex accumulating, various paleo-uplifts have favorable geologic conditions to discover large oil and gas fields

There are several gentle structure traps and small faults developed in central Sichuan Basin, some discovered oil-gas reservoirs are not related to anticlines. It is thought through related research that the lithologic trapsmainly developed in Xiangxi Group. According to the factors that controlled the formation of traps , paleo-geomorphology feature before Xiangxi Group deposition and fracture feature, lithologic trap types can be divided to four types, including: (1) stratigraphic-lithologic trap is related with stratigraphic pinch out;(2) diagenesis-lithologic trap is related with the facies variation of deposition and diagenersis;(3) differential compaction-lithologic trap is related with paleo-geomorphology;(4) fracture-lithologic trap is related with the transformation and adjustment of faults. Among theses, diagenesis-lithologic trap and stratigraphic-lithologic trap are regarded as the most important and extensive type distributed in central Sichuan Basin.

In consideration of the characteristics of high-maturity and low organicmatter abundance of Feixianguan Formation carbonate rocks found in Sichuan Basin,thermal simulation experiments has carried out on marlite samples collected from the fresh outcrops of Feixianguan Formation,Lower Triassic,at Shangsi,Jiange County,Northwest Sichuan. Not only revealed the evolving process and characteristics of hydrocarbon generation but also provided important parameter for the external estimation of Feixianguan Formation marls in Sichuan Basin. According to the results, themaximum yield ratio of oil hydrocarbon was up to 142.2kg per ton and the figure of Ro (0.63%~1.2% ) is the peak of oil generation; and themaximum yield ratio of gas hydrocarbon was up to 793.9 cubic meters per ton, and the H2S has been detected by the instrument of Agilent 6890N TCD in the gases collected from the different simulation temperature. All of these indicate that themarlite source rocks are of great hydrocarbon- generating potential and H2S under suitablematurity conditions in Sichuan Basin.

Erlian basin is a rift lacustrine basin developed on the Hercynian geosyncline folded base in Early Cretaceous, is featured by simple sedimentary feature, depositional cycle, small lacustrine transgressive, dry climate, salinization lacustrine water and multi-andnear sources. On the basis of sequence stratigraphy analysis of Bayindulan sag, Wuliyasitai depression, Jiergalangtu sag and Saihantala sag, the integrated sequence stratigraphy section of lower Cretaceous has been established and the vertical sequence of sandbodies distribution in three-order sequence has been concluded. The main conclusions are as follows: Firstly, under the influence of three phases of episodic activities, three two-order sequences is composed of three depositional cycles and three regional unconformities; Secondly, under the control of structure activities such as fault-block activities and the influence of three-order climate cycles and source recharge , lower Cretaceous can be divided into six three-order sequence; Thirdly, because fault activities is weak and fault slope is gently , fan deltas exist in steep slopes in early and later stages and subaqueous fans exist and turbidite fans exist in troughs in middle stage. Fan deltas distributed in gently slopes and braided river deltas develop alternately in all stages.

Based on matrix mineral, diagenetic sequence and fluid inclusions, are tested homotemprature, salinity and fluorescence of inclusions which coexist with hydrocarbon inclusions. The depth and geological age of oil inpouring are ascertained by combining with paleotemperature grad and sedimentary burial history. Inclusion analysis indicates that Fuxin uplift and Changling sag separate away aftermajor reservoir-forming stage of Fuyu oil layer, i.e. oil inpouring and reservoir-forming take place before Fuxin uplift upheaved in great force. The reservoir-forming of Fuyu oil layer includes two stages, i.e.the later Nenjiang period and later Mingshui period in Cretaceous. Inclusion study demonstrates oil reservoir being featured by up-source and down-storage, local-storage and verticalmigration. It is clarified that the source of Fuyu oil layer might originate anciently from Changling sag. Synchronously, it is pointed out that the "sweet point" controlled by source rock, overpressure, fault and sandbody are advantageous regions for oil exploration in the future

Biodegradation gas of heavy oil, belongs to secondary biogenic gas, is originated from the anaerobes biodegradation of crude oil. Generally, degradation gas of heavy oil occurs in shallow reservoirs and may be accumulated in large scale, so it has good resources potential. Biodegradation gas of heavy oil has closely associated with heavy oil, in other word, the majority of biodegradation gas of heavy oil distribute around the oilfield. Biodegradation gas of heavy oil is mainly composed of methane, and just a little of heavy hydrocarbon, also the content of N2 is high in nonhydrocarbon. The carbon isotope value of methane shows the features of high minus value with being around -100 to-55 While the CO2 shows unusual heavy carbon isotope value, so it is easy to be recognized.Methane would be generated from heavy oil anaerobic biodegradation, the process of biodegradation run through multi-tache, which was regarded as sort of water-hydrocarbon reactions involving anaerobe . At present, most of shallow heavy oil is resulted from anaerobic bacteria biodegradation, and several biodegradation gas pools distribute around the heavy oil accumulation that can be explored. Much attention would be paid to secondary biogenetic gas pools with high exploration potential in eastern petroliferous basins and in northeastern margin of Junggar Basin.

PetroChina has pushed ahead with progresses of science and technology according to the business development strategy of petroleum exploration and production by carrying out personnel stability, business stability and the direction stability of tackling key problem, and "four-order" methods ,including extending the mature technology, tackling bottleneck technology , developing new technology and introducing advance technology, during the Tenth Five-Year Plan. The company has made mighty advancements on lithologic oil-gas reservoirs, carbonate rock, foreland basin exploration, preliminary exploration of oil and gas and exploration engineering technology etc. These advances provide a powerful technological backing for discovery of oil and gas and increase of reserve in PetroChina

With the enhancement of computer capability and with the continual thorough of subsurface heterogeneity media, the technique of seismic wave imaging is progressed ceaselessly. At the complex structure area, in particular the area of low S/N ratio seismic data, the traditional reflection seismic exploration technique is faced with the obvious challenge. In such a case, the scattering seismic exploration technique may be a direction of technique development in the future, and its core is the reverse scattering image (RSI) technique. The RSI method will be especially used for separation of near-surface scattered noise, velocity analysis in heterogeneity media and complex structure imaged. The paper introduces the conception, theory and method of RSI. It's important that prospects of the potential of RSI method for complex structure imaged. All the works is offered the prophase technical storage for scattering seismic exploration

By comprehensive study of geophysical features of three volcanic oil-gas reservoirs with different structural setting and lithologic types in Songliao, Bohai Bay and Junggar Basins, it is shown that the acidic volcanic gas reservoir in Songliao Basin exhibits negative gravity, lowminor magnetic and relatively high resistivity anomalies and disorder, low-frequency and strong seismic reflections, the basic volcanic oil-gas reservoir in Bohai Bay basin represents positive gravity and high magnetic anomalies and disorder, low-frequency and discontinuous seismic reflections, and the medium-acidic volcanic oil reservoir in Junggar Basin has transitional gravity and magnetic anomalies, high resistivity anomalies and disorder, low-frequency and weak seismic reflections.According to the viewpoint that the vicinities ofmagnetic gradient belts close to or connected to source rocks are themost promising areas for oil-gas exploration, the favorable exploration zones in Changshen-1 well block, Zaobei and Shixi-Ludong areas in Songliao, Bohai Bay and Junggar Basins respectively are predicted comprehensively. An integrated exploration scheme for volcanic oil-gas reservoirs and relevant countermeasures are summarized

According to tuning effect of thin bed reflection, spectral-decomposition technique images the thickness and discontinuity of thin bed in frequency domain. It's a good and effective tool for identification and characterization of thin bed. Usually, common spectraldecomposition methods include short-time window Fourier transform (STFT), wavelet transform (WT), maximum entropy(ME), etc. STFT method has the window problem, which limits the vertical resolution, and cannot adapt the thickness transverse change of layers. Normal WT methods use scale parameter, which cannot correspond directly with frequency with ambiguity geological means. NonorthogonalWT avoids upper limitations under the control of frequency parameter directly. It can specify frequency band and distribution density in order to satisfy the identification requirement of thin bed and seismic sequence analysis, and benefit to characterize thin beds

Taking Sulige gasfield as instance, the relation between elastic parameters and gas reservoir has been discussed in detail in this paper. The research results include: Lam constant ( ), shear modulus ( ) and mass density ( ) all bear relation to lithology and porosity , and decrease with porosity increasing when lithology doesn't vary. The decreasing grade of is largest, next is , and is hardly affected when porewas filled with fluid. the ratios of / and vp/vs decrease when pore was filled with gas or oil, and / decrease more rapidly than vp/vs . But the ratios increase when pore was filled with water. / gas saturation relation is nonlinear and relate to porosity. But / porosity relation is hardlyaffected by saturation. Sowe can estimate porosity by using / then saturation by using / Based on the rock physical theory of fluid saturated porous media, the elastic parameter-porosity relation and elastic parameter-saturation relation have been build in the study area. Combining with prestack inversion and Paisson's ratio from the inverse elastic parameters, it can be used to predict the distributions of lithology and gas and estimate the porosity and saturation. The later drilling testified the reliability of the estimated results