Characteristics and distribution patterns of volcanic fractures in the Chaganhua Subsag of the Songnan Basin, China
Li Ning, Shan Xuan-long,*, Yi Jian, Li Zhong-bo, Cao Kai-fang, Tian Jun, Shi Yun-qian, and Leng Qing-lei
1. College of earth sciences, Jilin University, Changchun 130061, China
2. Exploration and Development Research Institute, Northeast Petroleum Branch of Sinopec, Changchun 130062, China
Abstract：
Fractures are critical control factors in volcanic reservoirs. Thus, studies on the prediction and distribution patterns of volcanic fractures are crucial for oil and gas exploration and development. Although considerable research has been conducted on volcanic fractures, targeted research on the spatial distribution patterns of fracture development remains limited in the literature. Two eruption modes, subaqueous eruption and subaerial eruption, have been identified in the Chaganhua subsag of the Songliao Basin, where gas resources have been discovered. Studying the diff erences in volcanic fracture development is highly important for understanding the law of oil and gas enrichment in volcanic reservoirs. On the basis of thin sections, cores, electrical imaging logs, and other data obtained from boreholes of subaqueous volcanic eruptions in the Songnan fault depression, we describe the characteristics of drilled fractures in detail and use 3D seismic data to extract intrinsic coherence, ant bodies, and Fourier series to extend the azimuthal anisotropic P-wave reflection coefficient, thereby predicting the spatial distribution of fractures at different scales. Moreover, through statistical analysis of quantitative evaluation indicators, such as fracture density and fracture development rate in different drilling wells, combined with the spatial distribution patterns of the predicted fractures, we compared and analyzed the relationships between the distributions of fractures and volcanic institutions, lithology, and volcanic facies. Results indicate that fractures are more developed in volcanic edifices located closer to faults. Considerable differences in fracture development are observed among lithofacies of volcanic rocks. Near faults, effusion facies, explosive facies and external clastic pyroclastic sedimentary subfacies are favorable for fracture development. This research provides a reference for investigating volcanic rock fractures of the same origins worldwide.
. Characteristics and distribution patterns of volcanic fractures in the Chaganhua Subsag of the Songnan Basin, China[J]. APPLIED GEOPHYSICS, 2025, 22(4): 1003-1018.
2025, Vol. 22 
