Abstract:

The 2^nd member of the Lower Triassic Jialingjiang Formation and the 3^rd member of the Lower Triassic Feixianguan Formation are the main gas-producing zones in TNB area,with the characteristics of deeper burial depth and thinner reservoir thickness.Although the major discoveries have been made in this area,the prediction of gas distribution remains the key factor for better exploration achievements.The spectral analysis based on wavelet transform,however,can be used effectively in gas distribution prediction.In connection with the reservoir characteristics of target area,the feasibility of gas distribution forecasting by frequency attenuation attribute is addressed by the comparison of gas logging data(total hydrocarbon detection) with frequency attenuation attribute,the reservoir forward modeling,and the interwell section examination of gas distribution.Their results indicate that different gas-bearing characteristics are exhibited horizontally and vertically in the 2^nd member of Jialingjiang Formation and the 3^rd member of Feixianguan Formation. The T₁j² gas reservoir(sand beach reservoir)is characterized by single gas reservoir with a larger pool area,while the T₁j³ Formation(oolitic beach re-servoir) is the multiple and vertically superimposed gas reservoirs with a relatively smaller pool area.

Key words: total hydrocarbon detection, frequency attenuation gradient, gas distribution prediction, TNB Structure