Research On Log Interpretation Method Of Gas Bearing Character Of The Neopaleozoic Combination Of Positive Rhythm, Inverted Rhythm Sand Body And Fractures In Ordos Basin

In this thesis, the author researches the gas bearing geologic model and log interpretation method of the different combination of positive rhythm, inverted rhythm sand body and fractures of Neopaleozoic in Ordos Basin by using core, well log, test data on base of regional geology knowledge. The main viewpoints are as following:(1) Sand body can be divided into four classes according to the combination relationship between positive rhythm, inverted rhythm sand body and fractures:positive rhythm sand body with developed plane-parallel fractures, low-angle declinate fractures and undeveloped subvertical fractures; positive rhythm sand body with developed plane-parallel fractures, low-angle declinate fractures and subvertical fractures; inverted rhythm sand body with developed plane-parallel fractures, low-angle declinate fractures and undeveloped subvertical fractures; inverted rhythm sand body with developed plane-parallel fractures, low-angle declinate fractures and subvertical fractures.(2) For the positive rhythm and inverted rhythm sandstone reservoir with developed fractures of Neopaleozoic, the falling means can enhance the success rate of gas zone interpretation. First of all, to interpret sand body rhythm. The shape of gamma ray curve of conventional log is the most sensible to sand body rhythm. Secondly, to interpret fractures. Imagery log can identify fractures accurately. Low angle fractures usually distribute on imagery log in the form of dark colored harmonic curve and subvertical fractures manifest dark colored line with small included angle or parallel against hole axis. When imagery log data are absent, fractures can be identified correctly by optimizing conventional log parameters which are sensible to fracture response and establishing interpretation model of cross plot. On base of the forgoing research, to interpret the gas bearing character of positive rhythm and inverted rhythm sand body comprehensively uniting conventional gas zone interpretation methods.(3) According to the foregoing method, the gas bearing character of 32 sandstone reservoir of 23 wells in this area had been interpreted. The interpretation result coincides well with trial production outcome, which demonstrates the feasibility of this method.