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The role of 3D seismic exploration in oil and gas exploration http://www.oilnews.com.cn/bk/images/070821/A012007011.jpg China Petroleum News Center Oil and gas are stored in underground oil and gas reservoirs. These oil and gas traps include structural traps, stratigraphic traps, as well as lithological traps; most of them are composite traps formed by the superposition of several types of traps. In short, traps are diverse and extremely complex. 3D seismic methods can accurately identify subsurface oil and gas reservoirs, as well as certain details of these reservoirs, achieving great success in the exploration and development of oil fields. 3D seismic surveys have four main functions in oil and gas exploration. First, it was necessary to determine the extremely complex structure several kilometers underground. The structure of the large oil field in the Bohai Bay area in eastern China is extremely complex, ranking among the most complex in the world. Some say that the structure here resembles a broken bowl that has been dropped to the ground and stepped on three times. The highly fragmented structure has turned the oil fields into small, fragmented units with extremely limited scale. The size of oil fields abroad is usually in the range of dozens, hundreds, or thousands of square kilometers, while the smallest block-shaped oil fields in eastern China cover only 0.01 to 0.05 square kilometers, making them a miniature version of oil fields. China’s seismologists have made use of 3D seismic data to accurately identify these small, fragmented pieces. Whether in terms of technology or performance, we are at the world’s leading level. Second, the structures that are deeply buried and have a gentle amplitude were identified. Some oil fields in the Tarim Basin in western China are buried 5,000 to 6,000 meters underground; the extent of the geological structures there is only 30 to 50 meters, and the inclination angle does not exceed 1°. Three-dimensional seismic technology was used to understand these structural features. The precision of seismic exploration is globally recognized to be between 3% and 5%, whereas in China, the precision of seismic exploration for such ultra-deep and extremely flat structures in the Tarim Basin has been improved by nearly 10 times. In this regard, we are also at the world’s leading level. Thirdly, it has provided excellent results for the study of oil and gas reservoirs. Using 3D seismic data, it is also possible to determine with high accuracy the distribution range, thickness, porosity of these reservoirs, as well as their oil and gas content. In this regard, we are roughly on par with the world’s advanced levels. Fourth is to serve oil field development. Before developing an oil and gas field, a development plan must be prepared, which determines how the oil wells will be arranged. During development, various measures are taken to increase oil and gas production, such as water injection, gas injection, chemical flooding, and polymer flooding, in order to extract as much oil and gas as possible from the underground reservoirs. There are also many methods for increasing production in the later stages of development. 3D seismic surveys can also provide accurate data for these specific tasks, to be used in oil field development. In this regard, we have kept up with the global technological trends and begun to shift from oil exploration to oil production.