The factqrs including lithologic characteristics

geophysical signature

hydrocarbonbearing and formation pressure have effects on seismic wave velocity. According to nonconstrain least-square fit of drilling and well-logging data

V=AΦ+BΨ+Ch

1/n

would be anideal mathematical model in expressing the relation between velocity and porosity. On the basis of the above mentioned model

the combined model of three-element medium is proposedin this paper. The prediction of mudstone distribution in reservoirs and then the prediction ofporosity were' made by applying the response of interval velocity to the content of mud. Thismethod is used to predict the porosity distribution of T-J sandstone reservoirs in TarimBasin

and the result is good.