Structural Style And Its Relations To Hydrocarbon In Machang Region, Dongpu Sag

Based on seismic data and former research results at Machang in Dongpu sag,our group did a lot of works like seismic interpretation, structural sketch map, faults displacement distributing chart (displacement-distance graphs), structural evolution section and so on. Firstly, by identifying the stucture style ,there are several styles as follow: basement strike-slip fault, listric fault ,normal fault sysytem, oblique-slip normal fault, normal fault-related folds,ect. Mainly, listric fault, oblique-slip normal fault and fault-propagation folds have been describede in detail. secondly, according to the variation of the strucure along strike and displacement-distance graphs, we find out the transition structure zones and classified them according to the classification criteria. Finally,we discussed the relationship between structure and oil.Main results and conclusions we got are:①Identifying the main structure styles in this area: listric fault, oblique-slip normal fault, fault-propagation folds. The listric fault style belong to the basement controlled fracture zone, it’s characteristic is that the fault displacement is large, the sediment is strictly controllde by it and the wedge-shape block can be seen. The characteristic of the oblique-slip normal fault is that secondary fault develop greatly, the accompaned rootless flower structure can be found. The characteristic of the fault-propagation fold is that the anticline-syncline pair and arcuate fault can be seen from the cross section in the cover above the master fault. According to these features,we recognized them. These three styles developed mainly in the Machang fault system and Sanchunji structural system.②It is proposed that there are two main transistion structure zones which are located near Line 500 and Line 1200. The main style of transition structure is transfer ramp. The composition of strucure in the two side of the transition structure zone vary apparently from the cross section; the strike of the structure vary mostly near the transition structure zone from the structural sketch map; the thickness is controlled by the transition structure zone from the unit isopach map. The origin of the transition structure zone is relevent to strike-slip and differential extension in the basement.③verifying the responding relationship between segmentation and transition structue zone.with displacement deficit on the joining site,where the develops.④analysing the relationship between the fault system,transition sysytem and reservoir forming. Machang fault help the oil move during its evolution; the transfer zones have great influences on sedimentation and hydrocarbon cccumulation.