Characteristics of strike-slip faults on the western Shaleitian Uplift and their control over oil and gas accumulation

Based on the data of 3D seismic, drilling, logging and lithology, the plane and sectional characteristics of the F2 strike-slip fault in the west part of the Shaleitian Uplift are described in detail in this paper. The forming mechanism of the fault is simulated by physical experiments, and the controlling factors over oil and gas accumulation is discussed. The results show that the plane characteristics of F2 strike-slip fault in the west part of Shaleitian Uplift are quite different with its sectional features. On the plane, the middle and deep parts of the fault are smooth and isolated, and the shallow part is a broom-like fault consisting of several secondary faults. On the section, however, the southwest section of the F2 strike-slip fault shows a "flower-like" structure, whereas the northeast section is in a simple "Y" shape. The physical simulation suggests that the forming mechanism of the fault is jointly controlled by the pre-existing basement fault and the lithology of the two sides of the fault. The southwest segment is dominated by weak extension in Paleogene, superimposed by the strong dextral strike-slip in Neogene. In the plane view, however, it is in a broom shape. The northeast segment of the fault shows strong extension in Paleogene, superimposed by dextral weak strike-slip in Neogene, resulted in a horsetail style of structure. The development and evolution process of F2 strike-slip fault is the major factor controlling the shape and scale of traps in the study area, the development and formation of sandstone skeleton transport system and the fault transport system as well as the scale and type of sedimentary reservoirs of the Dongying Formation in the study area. Moreover, it may also improve the physical properties of Archean buried hill reservoirs and provide a reference for future exploration and evaluation in the study area.