China’s foreland basins are one of the selected exploration zones for the sustainable development strategy. Based on China plate and the continental structural development, the authors summarize the characteristics of China’s foreland basins according to the present situation of the oil and gas exploration of the foreland basins and the geological structural background for formation of China’s foreland basins as well as the analysis of dynamic mechanism. They come up with the name of “the foreland basins of China type” on the basis of comparison with the foreland basins in foreign countries. China’s foreland basin is quite different in terms of hydrocarbon source rock type, the oil and gas property of the basin structure and the stages and times for oil and gas migration and accumulation. The oil and gas prospect of China’s 15 foreland basins are divided into the favorable, relatively favorable and prospective categories on the basis of integrated analysis of such factors as the reservoir formation conditions for China’s foreland basins, the amount of the hydrocarbons layers, the storage conditions for stable continental peripheral hydrocarbon source rock layers of marine facies, the time for basin deformation stages, the size of basins and the present exploration situation. They come up with five key issues existing in the study of China’s foreland basins in the attempt to provide the reference for the people in charge of exploration to make decisions.

Miocene to the present time is the most active period for the post-fault thermal subsidence in China’s offshore Tertiary basins. Accompanied with the post-fault structural activities again, the fault activities are also extremely active. Fault is the most direct and important form to reflect the new structural movements in this period. The fault activities in this stage (since 5.3Ma) are called the late-stage faults. The fault activities in China’s offshore basins in this stage are different in characteristics and distribution. The difference is even great in the same basin but the different structural units. However, the fault activities in this stage have some common characteristics no matter they take place in the basins in Bohai Sea, East China Sea or the northern part of South China Sea. They are accompanied with the sag-controlled basement faults and successive activities of regional faults belonging to the same deposit or restoration of activities. There are a large amount of faults during this stage, small-scale and arrayed in the feather shape. They are mainly distributed in the nearly eastwest and northwest-west directions. The fault-active regions and fault activities in this stage have the key effect on the oil and gas migration and accumulation in the late stages, which shaped and renovated a number of late-stage traps, formed the conducting systems for oil and gas migration, adjusted and controlled the oil and gas migration and accumulation in this region and final distribution of oil and gas fields. The study of the development and distribution characteristics of those fault activities in this stage is of great importance to guide the oil and gas exploration of these basins.

From Late Jurassic to Early Cretaceous, the northeast part of China entered the continental peripheral structural development stage of the Pacific-rim structural region. There developed a series of strike-slip pull-apart rift basins in the swallow-shaped array. They have the following oil and gas migration and accumulation characteristics. The hydrocarbon source rock of successive deep rift and multistage overlapped rift is large in thickness, good in quality and high in thermal development. The oil and gas storage conditions are desirable with high abundance of oil and gas resources. One of the prominent characteristics for the strike-slip pull-apart rift is that the hydrocarbon source conditions are rapidly becoming poorer towards the two sides from the deep fault groove. Therefore, the high-abundance deep fault groove controls the oil and gas abundance. There develops four compound oil and gas accumulation zones: sag-controlled strike-slip fault belt, deep groove periphery, slop fold belt of slop zone and uplift on the periphery of rift. The oil and gas abundance is of the middle to relatively low degree owing to the strong structural separation and the small scale of the sedimentary system, thus developing a large number of the medium-size and small oil and gas fields. There is a great difference in thermal development degree with a variety of mother rock types. The oil and gas migrated and accumulated in multiple stages with co-existence of oil reservoirs, gas reservoirs and oil-gas reservoirs. The region has experienced multi-stage multi-stage structural movements following the Late Jurassic-Early Cretaceous rifts, leading to multi-stage oil and gas migration and accumulation. The difference is apparent in the ratio of the original and secondary oil and gas reservoirs in each block owing to the difference in the oil and gas migration and accumulation conditions in each block. Therefore, if the blocks and target layers are optimized and selected according to the oil and gas reservoir characteristics in the strike-slip pull-apart rift basins in this region, the reserves will be raised significantly in the future.

This paper makes full analysis of the mechanism of oil and gas migration and accumulation for the special reservoirs, such as lake shallow-water beach and bar oil and gas reservoirs, in the subtle oil reservoirs of this oilfield. The main content covers lake shallowwater beach, bar sedimentary characteristics and lake shallow-water beach, bar oil and gas reservoir types and briefings about exploration cases, study of exploration methods and analysis of exploration prospect. The analysis clarifies the key conditions for the migration and accumulation of the oil and gas reservoirs and distribution of structural locations, providing the theoretical basis for search of the oil and gas reservoirs of this type.

Upper Tertiary in Bohai oil province is the sedimentation of fluvial facies, which has not source rock. The accumulated oil and gas in the trap came from the Lower Tertiary hydrocarbon source rock 2000~5000 meters below. Therefore, the study of oil and gas migration is of great importance. Fault is the main migration channel in Bohai oil province. Based on the exploration practice for decades, the large fault of successive development is regarded as the migration channel for shaping of the large and medium-size oil fields. The small fault in the activities of the late stages is limited in migration capability. The straight strike-slip fault is relatively poor in migration capability. The stratum-fault controls the position of oil and gas accumulation. The Upper Tertiary oil fields in the depression are mostly distributed in the downthrow block of the large fault

With application of the sequence stratigraphy theory and method, Feixianguan Formation in Northern Sichuan is divided into five sequences and ten regional systems and the sequence stratigraphic configuration is also established for study of Feixianguan Formation. Based on the study of sedimentary facies distribution in the sequential stratigraphic configuration, it is found that the oolitic shaol area on the platform periphery of Feixianguan Formation in Northern Sichuan is about 30,000 square kilometers, distributed in three belts. Of those, two belts are controlled by the Kaijiang-Liangping sea trough while another belt is controlled by Exi-Chengkou sea trough. Five favorable plays are selected on the basis of integrated analysis, such as Wenquanjing-Jinzhuping, Tieshan-Huangnitang, Shatuo-Macaoba, Yilong-Yingshan and Jiangyou-Guangyuan. Of those zones, Wenquanjing-Jinzhuping and Tieshan-Huangnitang are the relative mature zones for exploration and further exploration should be focused on these two zones. The three zones of Shatuo-Macaoba, Yilong-Yingshan and Jiangyou-Guangyuan are under low degree of exploration and study. Integrated geological study should be stepped up for those three zones in order to seek the favorable traps to make breakthrough as soon as possible.

The reserves of oil and gas reservoirs can be divided into the proven reserves, controlled reserves and predicted reserves according to the different stages of understanding the oil and gas reservoirs. Prediction study of the proven oil and gas reserves growth trend is the basis for the oil companies to formulate the strategies for reasonable increase of the reserves and production as well as exploration and development. In the opinions of the authors, the scientific methods should be adopted to reasonably predict and estimate the future trend on the basis of the available geological information. It is necessary to analyze and study the source of the newly additional proven reserves, the conversion of the controlled and predicted reserves and the prediction method for the newly additional proven reserves so as to achieve the satisfactory results. This method can be used as reference for the departments in charge of exploration and development

Based on the high-density sampling, the new method and technology of geochemical exploration, which is integrated of the technology to directly detect oil and gas existing in the soil and the technology to extract the soil-absorbed hydrocarbon, is used in progressive exploration and development of the shallow-layer Dawanqi Oil and Gas Field. Application of the modern oil geological theory – the new method for analysis of the oil-generating system, combined with oil and gas prediction based on the abnormalities from geochemical exploration of structures – makes the successful rate of exploration wells rise significantly and the production of oil fields jump rapidly. This method is indicated to have a promising prospect for application in exploration of the shallow-layer oil and gas fields.

The overseas oil and gas development will first face the feasibility of the concrete project. The basic study should be stepped up from the strategic viewpoint. As for the latter, worldwide oil geology and resources, China’s geographic peripheral oil and gas characteristics and international oil market are three important fields. The Middle East, Northeastern Asia and Southeastern Asia-Australia are the key regions from the angle of geographic peripheral oil and gas. We should involve the overseas oil and gas operation into the international market and make ourselves stronger in competition and cooperation to assure use of international oil and gas resources.

As for the comparison of investment and cost in the seismic exploration of the current oil department, the use of the cost unit like kilometer and square kilometer cannot reflect the unit length or how many data points the unit area has or how many times each point receives the data, namely unable to reflect the engineering workload of seismic exploration. The data points and the times each point receives the data in the seismic exploration are raised as the engineering workload for the seismic project. The cost-calculating unit is “point-time.” This article discusses calculation of unit length and the “point-time” in the unit area, the relations between the point-time and the unit cost variation as well as calculation of the seismic engineering workload in the concrete project.