From the exploration guiding ideology, research ideas, theoretical and technical progress, the research process of oil and gas exploration in southern China can be divided into the following stages.
1.2.2. 1 under the guidance of "trough-platform theory and anticline oil control theory", the ground structure was searched and drilled (before 1963).
The exploration work at this stage is characterized by ground geological survey and shallow well drilling. Platform theory and anticline oil control were the main theories and guiding ideology of exploration at that time. This period is the primary stage of marine and Paleozoic oil and gas exploration in southern China, and geological mapping and looking for surface structures are the main methods. Permian, Triassic and Weiyuan Sinian gas fields have been discovered in south Sichuan and southwest Sichuan gas fields. At this stage, the concept of "reservoir-forming combination" has not yet been formed, so exploration and research work are inseparable.
1.2.2.2 Under the guidance of "petroleum exploration theory of oil-bearing basins", the understanding that there are multiple sets of source-reservoir-cap rock assemblages and preservation conditions are the key is formed (1964 ~ 1978).
During the period of 1964, high-yield natural gas was obtained in Dengying Formation of Sinian system in Weiyuan, Sichuan, reminding people to explore from shallow to deep. From 1966 to 1972, more than 60 wells have been drilled in Guizhou, central Guangxi and western Hunan and Hubei (nearly 30 wells in Guizhou and central Guangxi and 33 wells in western Hunan and Hubei). Due to the lack of regional caprock and extremely active groundwater in these areas, drilling failed one after another. People gradually realize that there are multiple sets of source-reservoir-cap assemblages in marine strata, and there is more than one Deng Ying Formation in drillable target strata. The reason of groundwater outflow is that the preservation conditions are not good enough. After 1972, oil and gas exploration turned to clastic rock coverage areas such as Shizhu syncline, Chishui area, Luoping fault terrace and Dangyang syncline. This transfer accelerated the development of Chishui gas field and discovered Jiannan gas field.
In the study, the oil exploration theory of oil-bearing basins is used, and the viewpoint of lithofacies paleogeography and paleostructure controlling oil is cited, and the structural traps are found by using the surface geological survey method. One of the breakthroughs in exploration research at this stage is the understanding that "there are multiple sets of source-reservoir-cap combinations" and "preservation conditions are the key" in the southern marine strata, which effectively guides the transfer of exploration targets. Although the concept of "lower assemblage" has not been clearly put forward, the strata below Silurian have been regarded as important exploration and research target strata, and the lower assemblage has been regarded as the main exploration and research target strata in some areas (such as Xiangxi and Hubei).
1.2.2.3 is characterized by "comprehensive evaluation and research", and puts forward the viewpoint of "effective hydrocarbon source, effective reservoir space, effective trap, effective sealing condition and effective reservoir-forming period" (1979 ~ 1992).
1978 in the second half of the year, the headquarters of Jiangsu, Zhejiang, Anhui, Yunnan, Guizhou, Guangxi, Hubei, Hunan and Jiangxi were established one after another, aiming at effectively coordinating the exploration work in the three places and selecting exploration target areas. Drilling in exposed areas of marine carbonate rocks has basically stopped. In addition to preservation conditions, oil generation and storage conditions are also considered for drilling in covered areas, such as drilling in Shiwandashan and Shenhu-Tuitang areas. The number of drilling wells put into offshore horizon exploration is only one tenth of that in the first stage and one quarter of that in the second stage. At this stage, 39 wells were drilled, and 26 wells were drilled in Jurong area. Although seismic data are used in well location deployment, poor seismic data quality and structural trap failure often lead to drilling failure.
In particular, the study of marine strata in southern China has been included in the national key scientific and technological projects for three consecutive five years. Based on the theory of plate tectonics and the study of Mesozoic and Paleozoic marine sediments, structures, oil and gas evolution, oil and gas accumulation, geological conditions and resource potential prediction in the Yangtze region, this paper puts forward the understanding that oil and gas in marine carbonate areas in the Yangtze region have "intraplate deformation and late secondary accumulation", and puts forward "effective oil and gas sources, effective storage space, effective traps, effective sealing conditions and effective accumulation period" in the evaluation of oil and gas accumulation zones. These research results not only selected a number of favorable exploration blocks for the middle and lower reaches of the Yangtze River and Yunnan, Guizhou and Guangxi, but also made a new leap in technical ideas, technical methods and understanding of geological conditions in the target area.
1.2.2.4 features "comprehensive evaluation research on key basins", and defines the evaluation idea of "effective oil and gas preservation units and late reservoir formation" (1993 ~ 1998).
1July, 1993, the oil and gas exploration project management department of Sichuan-Hubei Border Region and Southern New Area was established. 1In July, 1996, China Petroleum and Natural Gas Group held a conference on oil and gas exploration in South China in Sanya, Hainan Province, marking the beginning of oil and gas exploration in South China in key basins.
Under the guiding principle of "overall evaluation and optimization of blocks, unified planning and deployment, and strict exploration procedures", and under the guidance of new theories, technologies and methods, a comprehensive evaluation study of key marine basins in southern China was established. During this period, the exploration idea of "focusing on the lower Paleozoic, focusing on large and medium-sized structures and focusing on natural gas" was clearly put forward for the lower Yangtze area. The research workload of regional evaluation and basin (block) evaluation was deployed in the southern new area, and the old geophysical data were reprocessed and interpreted. MT, geochemical exploration, gravity, aeromagnetism and two-dimensional digital seismic exploration have been carried out; The old well was retested. A small number of exploration wells and scientific exploration wells have been deployed in key basins. However, due to the understanding of the complexity of the structure and the influence of the accuracy of geological data, there is no oil and gas breakthrough except the Yang Du 3 well in the Yangduxi structure of Shizhu syncline, which produces 2× 104m3 gas per day in the Jialingjiang Formation of the Lower Triassic. These works have made necessary preparations for a comprehensive understanding of the discovery and evaluation of key target areas in the south and basins.
1.2.2.5 Carry out research and tackle key problems at different levels, and form the understanding of "multi-stage reservoir formation, oil-gas conversion, late adjustment and dynamic balance" (after 1999).
After the reorganization from 65438 to 0999, Sinopec Group put the resource development strategy in the first place. From May 65438 to May 0999, the Southern Ocean Oil and Gas Exploration Project Management Department was formally established. According to the strategic deployment of the joint-stock company "actively preparing for going south", the oil and gas exploration work is actively organized and implemented from three levels: strategic development, strategic breakthrough and strategic preparation. After the Huairou Conference in 2000, the exploration focus shifted to the northern margin of the Yangtze River, and oil and gas exploration achieved "one breakthrough and six positive progress". Puguang gas field, the largest gas field in Sichuan Basin, was discovered. In 2004, Ocean New Area submitted proven natural gas1143.6×108m3, controlled natural gas 555.88× 108m3 and predicted natural gas 1390.95× 108 m3.
At present, scientific research is mainly carried out at different levels (basic research, comprehensive research and zone evaluation) according to the situation of offshore oil and gas exploration, production and research in southern China. China Petrochemical Company organized a scientific research team combining Industry-University-Research, vigorously developed the theory of marine reservoir formation in southern China from three aspects: basin formation, hydrocarbon generation and reservoir formation, deepened the research on marine reservoir selection in southern China and the study on the law of gas reservoir formation and enrichment in the Middle Paleozoic in southern China, and achieved a series of research results and progress. At the same time, the gradual improvement of geophysical exploration technology (three-dimensional seismic exploration, comprehensive geophysical exploration, etc.). ) and engineering technology have laid a solid foundation for the new discovery of oil and gas.