To evaluate AVO uncertainty considering correlation: a case study of tight sandstone reservoir

Hangjinqi tight sandstone reservoir has low porosity and permeability. Its pre-stack AVO response are complex and ambiguous, so it is necessary to evaluate its AVO uncertainty. Based on experimental core data, we summarize the rock physical characteristics of this reservoir. Then expand these data with equal probability using Latin hypercube sampling, and preserve correlation between input parameters using Iman-Conover method. So AVO uncertainty evaluation is carried out with expanded data. The results show that the elastic property of Hangjinqi tight sandstone reservoir is controlled by mineral content, porosity and pore fluid. The pre-stack AVO forward modeling results show that the different physical parameters of the reservoir lead to different AVO responses. With the increase of porosity, the AVO intercept increases and the gradient decreases, but some porosity overlaps, and the results are uncertain. The AVO attributes of gas and water saturated reservoirs are independent of each other, and the uncertainty is low. AVO uncertainty evaluation using the workflow in this paper can provide rich information and effectively reduce the exploration and development risks of tight sandstone reservoirs.