Controlling effect of normal drag structure on the internal reservoir architecture in an alluvial fan

The coupling relationship between the normal drag structure developed in the hanging wall of a contemporaneous reverse fault and the internal reservoir architecture in alluvial fan, based on core, outcrop, dense well and seismic data is unclear. Well-to-seismic calibration, elevation differences between key and target strata, hierarchy bounding surface analysis and comprehensive geological analysis have been used to clarify this relationship. The differential distribution characteristics of internal reservoir architecture under the control of normal drag structure were studied. Research shows:(1) Normal drag structure has 4 essential features:asymmetrical anticline uplift morphology, uplifted extent difference exists in different places with cumulative effect, extensional tectonic and unconformities often appear, successive development and distribution range gradually change. (2) The bed form of differential uplifting caused by normal drag structure controlled the dispersion and filling with sandy conglomerate, which was different from the traditional mode, that is, different architecture may appear at the same distance to the fan root. (3) Normal drag structure controlled sediment accommodation space. Uplift made the space decrease, and on the wings increase instead. On the other hand, uplifting sedimentary bed form affected the direction of paleocurrent and changed the distribution of internal architecture in an alluvial fan reservoir. Architecture element type and scale no longer changed along the radial direction.