A Novel Geophysical Approach to Investigate Mixed Wettability Effects Using Spectral Induced Polarization (SIP)

Abstract Conventional techniques for measuring wettability, such as contact angle measurements, Amott-Harvey, and USBM, are often time-intensive, require polished surfaces, or lack scalability. Advanced methods like Nuclear Magnetic Resonance (NMR) and dielectric techniques provide non-destructive alternatives but face challenges such as limited penetration depth and high frequency ranges (MHz–GHz), potentially overlooking key polarization mechanisms relevant for fluid-rock interaction. These limitations hinder the comprehensive characterization of reservoir properties, underscoring the need for innovative approaches. In this study, we propose a novel geophysical method known as Spectral Induced Polarization (SIP), as a promising approach to overcome these challenges in the petroleum field. The SIP technique is established for near-surface environmental applications but has limited exposure in the oil and gas domain. SIP offers a broader frequency range (1 mHz to 10 kHz) which improves the depth of investigation and is also proven to amplify the impact of fluid-rock interaction through the electrical double layer. We conducted a well-controlled experiment combining water-wet components (sand) with oil-wet particles (pyrite after aging with crude oil). Complex conductivity measurements through SIP were conducted before and after introducing the oil-wet component at full brine saturation. The results revealed significant impacts of wettability changes on SIP responses. At full brine saturation, the presence of an oil-wet component decreased conductivity throughout the frequency range compared to the water-wet test, where an increase in the phase-shift characteristic frequency and magnitude was observed in the presence of oil-wet pyrite particles due to the discontinuities of the electrical conductivity pathway and impact on the polarization mechanisms that were amplified with the presence of oil component. These findings highlight the potential of SIP tool to evaluate the wettability changes. This novel application of SIP provides fundamental insights into wettability changes, leveraging the tool's sensitivity to fluid-solid interactions. By integrating geophysical techniques with controlled laboratory experiments, this study lays the groundwork for using SIP to characterize wettability changes more effectively. These findings pave the way for developing a SIP logging tool or incorporating SIP sensors in petrophysics laboratory setups (like core flooding). This could revolutionize industry practices by providing a robust, field-deployable solution for reservoir characterization and enhanced oil recovery strategies.