Analysis on the Elements of Fracture-cave Corresponding to the Beadlike Reflection of Ordovician in Tazhong Area
Beadlike reflection is a typical reflection feature of fractured-vuggy reservoirs in Tazhong area.The corresponding relationship between the location of venting leakage or o-verflow and the beadlike reflection phase shown in the actual drilled reservoir is complex,and the design of drilling trajectory is very ambiguous.In this paper,the beadlike reflection characteristic types of fractured caves and their combinations in Tazhong area are analyzed and summarized.The fractured caves with different factors such as vertical and horizontal scale,filling speed,shape and spatial combination mode are designed.The corresponding re-lationship between the leakage position of drilling venting and the beadlike reflection charac-teristic types and reflection phases is clarified based on modeling of wave equation and analy-sis of seismic reflection.It is pointed out that near the zero phase between the strong trough and peak of its beadlike reflection is most likely the development position of a single karst ca-ve,or the combined center of multiple vertical and horizontal karst caves biased towards the position of the karst cave with the lowest velocity.
beadlike reflectionelements of fracture-caveforward modellingdrilling trajec-tory design
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