Application of ultra-deep sandstone reservoirs prediction technology under controlled seismic facies in Yudong block of Tabei Uplift, Tarim Basin, China

Thin sand layers are widely developed in the Cretaceous Baxigai Formation in the Yudong area, western Tabei Uplift, and series of lithologic traps controlled by the structures are formed. The thickness of the target layer is 3–5 m, which is beyond the resolution of conventional seismic data; this causes the prediction of the reservoir to be difficult. Starting from the forward simulation, a forward model was designed based on the well logging data and characteristics of the strata in the well area to analyze the impact of different thin reservoir development modes on the seismic waveform. The experimental results show that the amplitude of thick sandstone is strong, while that of the thin sandstone is weaker. When mudstone barriers develop in sandstones, the amplitude decreases and the trough widens. Based on the results above, the seismic facies plan is formed by clustering the two attributes of wave trough width and amplitude, and the qualitative prediction of the reservoir can be realized on the plane by referring to the drilled rock information. Based on this, high-resolution seismic waveform inversion was carried out to achieve vertical reservoir prediction. The inversion results on the profile are higher than those of well logging. Furthermore, geological knowledge is achieved on the plane and good application results are obtained.