There are various seismic reflection types formed by channel sands in Guantao formation of Neogene in KD1 area
due to a transitional sedimentary period from braided stream to meandering river.It is usually inapplicable when
tracking strong seismic events to predict channel sand.So it is necessary to know the reflection features before we
track sands using seismic data.Firstly，we analyze the lithology combination，velocity difference and thickness
distribution according to the compare between reservoir and surrounding rock via all practical wells in primary sand
groups.Then we build forward models to get the various seismic reflection types in condition of different lithology
combination and thickness assemblage.At the same time，we analyze the influencing factors resulting in the variety
of amplitude.It is pointed out that most channel sands could form laminated sand-pack reflection and the
probability of sand corresponding to strong amplitude is approximately 68%.With the same sedimentary
background，the thickness of mud interlayer and velocity difference between sand and mud are the main
influencing factors.So we should not aim only at those “light-spot” while deploying wells.It is important to choose
favorable sedimentary facies and hydrocarbon accumulating area by geological analysis.The sands which formed
weak seismic reflection might still contain oil or gas.The exploration practice shows the analysis method has a
certain guiding significance for tracking sand and selecting drilling-well target.
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