Pore fluid estimation using effective workflow of Poisson impedance analysis

Abstract

In the fields of oil and gas exploration, various quantitative seismic interpretation techniques have been developed to identify lithology and pore fluids based on the rock physics. However, discrimination between oil and brine in pores is often difficult because the seismic response of oil and brine are similar. Poisson impedance (PI) is an effective indicator for distinguishing oil from brine in pores. Target correlation coefficient analysis (TCCA) is widely used to calculate the "c" factor of PI. However, PI analysis using the TCCA method can lead to misinterpretation when the resistivity log is affected by lithology and porosity, as well as the pore fluid type. To overcome this problem, we developed a more effective PI workflow composed of three steps that focus on lithology impedance, porosity impedance, and fluid impedance. In each step, we exclude the unnecessary area for hydrocarbon exploration such as shale, tight, and brine-saturated areas. We applied our method to marine field data that contained shale and tight intervals and demonstrated that the proposed approach can be used to identify potential oil reservoirs more effectively from seismic data.