关键词: 深部煤层气, 地震勘探, "双甜点", 地震—地质—工程一体化, 钻遇率

Abstract: The deep coalbed methane (CBM) resources are abundant in Ordos Basin, and three difficulties in seismic technology are encountered in CBM exploration and development, including low signal-to-noise ratio of loess mountain data, thin thickness and rapid lateral changes of coal seams, and high requirements for sweet spot prediction accuracy. To realize the large-scale high-efficiency development of deep CBM, in recent years, significant advances have been made in the integrated technology of seismic acquisition, data processing and interpretation as well as seismic geology and engineering for deep target CBM reservoirs in the eastern margin of Ordos Basin. The application of "wide azimuth, broadband, and high-density" seismic acquisition technique and "high fidelity, high resolution" data processing technology in loess mountain area provides a high-quality data for seismic exploration of deep CBM. As a result, the main frequency of target layer for CBM seismic exploration can reach up to 40 Hz, and the frequency band can be broadened by more than 10 Hz, thus steadily improving the imaging accuracy. The fine structure interpretation and reservoir evaluation technologies have laid a solid foundation for the location of dual CBM sweet spots. The predicted thickness of coal seam is 5 m and the coincidence rate between the predicted and measured values of fractures can reach 79%. The application of seismic geology and engineering integrated technology has realized the effective extension of seismic exploration to geological development, increased the drilling encounter rate of coal seams to more than 97%, and the output of horizontal wells has reached 100 000 cubic meters, providing strong support for the efficient production of CBM in the study area.

Key words: deep coalbed methane, seismic exploration, dual sweet spots, integration of seismic geology and engineering, drilling encounter rate