Depressurization as an Effective IOR Strategy

Reservoir depressurization is increasingly being recognized as the most cost-effective Improved Oil Recovery (IOR) technique in many clastic reservoirs. Early research into reservoir stress analysis has revealed a complex relationship between reservoir flow properties and the prevailing effective stress conditions.
This paper presents findings from a series of studies conducted at The Robert Gordon University over recent years. These studies reaffirm earlier research, demonstrating that reservoir flow efficiency and recovery factor are significantly influenced by initial reservoir permeability, the Reservoir Quality Index (RQI), and the stress path.

Preliminary results suggest that the impact of the stress path on flow efficiency and recovery factor is dependent on both RQI and the Flow Zone Indicator (FZI). FZI is a distinctive parameter that integrates geological characteristics such as texture and mineralogy to differentiate pore geometrical facies, referred to as hydraulic units. The stress path represents the magnitude of stress anisotropy within a reservoir. Stochastic analyses have been conducted using various field data, and the results can be utilized to guide decisions regarding optimal reservoir candidate selection and the operating conditions necessary to ensure successful improved oil recovery.