125 Dongying Sag River Fault Geometry And Recycling Its Control Of The Deposition Of Sand In The Sand Body

The fault He125 at south margin of central lifting belt of Dongyang depression, which was an active growth fault during Shahejie formation is studied. 1) The regional geology and evolution background of the fault He125 are analyzed. The evolution history of the fault He125 is build up based on seismologic and drill data. 2) The T4～T6 segment of the fault Hel25 was interpreted in detail and its geometry was reconstructed. 3) The shape of the fault He125 in plane was illustrated by using striking, rotation and angle of branch fault. And its profile features include fault horizontal slip, vertical slip, and dip, fault throw and growth index were interpreted by selecting precise points. Based on these features, 3-D structural elements, fault plane system and structural style were studied. 4) The formation mechanism and kinemics characteristics of the fault He125 were studied. And structural stress of the fault Hel25 was simulated by finite element analysis.Based on the theory of high-resolution stratigraphy, combined with 3-D seismic data interpretation and paleontology, log, geochemistry and other data, the frame of equal-time formation with high resolution was set up and the control of the fault on stratigraphy was studied. Based on the comprehensive analysis on the shape, position and distribution of sand body, combined with fine interpretation of fault, the low-sequence fault's control on stratigraphy and sedimentation, that was, the fault controls sedimentation by varying accommodate space, were studied.Based on the distribution of the third middle member turbidite sand body in drop part of the fault He125, combined with log and seismic interpretation, according to sedimentary facies and sedimentary system, with the aid of theory of structure geology and sedimentology, sedimentary micro facies and distribution were discussed and the geological model of turbidite sand body was established. The curve-fan-couple phenomina, that was, cross section system controls the shape of sand body and its extent, was proposed. Some turbidite sand body in drop plate can be found where the fault curves. The reason is that when the frontal sand body in delta collapses, it firstly reaches the place where upper plate curves, and corrode unceasingly down to produce sand accumulation with bag shape, and amounts of sand bodies collapse along fault plane and gather in drop plate to form promising reservoirs. Based on above work, the control mode of the fault He125 on the development of sand body was established and a prediction about where a good play exists was made.