Abstract: The orthogonal seismic tmace set up on the concept of complex seismic trace is combined with the real seismic trace to form the imaginary part and the real part of the complex seismic trace. Though the phase shift of 90to real seismic trace, the orthogonal seismic trace is taken, and the shape of the seismic wavelet turns from the zero-phase wavelet to the unsymmetrical wavelet. So the orthogonal seismic trace can reflect clearly some fuzzy and dim amplitude information in the record of the real seismic trace. Generally in the routine display profile, orthogonal seismic trace and real seismic trace have not obvious dfference but 90° phase diference. After the suitable display parameters are adopted, the diference in amplitude becomes relatively obvious. On the 2D offset seismic profile and its orthogonal seismic trace profile, comparison and explanation of the ampltude value corrsponding to the same interval are conducted in order to find out the abnormal amplitude area in plane, ie. the distribution range of possible lithologic anomalous body. By means of this method, one abnormal amplitude ditribution area is found in Silurian gystem, the west and north of Well TZ32 in Tarim basin. The anomaly well matches the driling results of Well TZ34 and Well TZ32.

Key words: orthogonal seismic trace, real seismic trace, lithologic anomalous body, amplitude, Well TZ32