Accurately determining the oil-to-water ratio in storage tanks is essential for reliable water cut production data, particularly in rag layers where stable oil-in-water emulsions form. Traditional measurement techniques—such as capacitance, conductance, acoustic, and gamma ray methods—often fall short due to cost, accuracy limitations, or environmental concerns. To address these challenges, a patented electromagnetic sensing method was developed to monitor fluid composition profiles in storage tanks.

This approach was tested using a coaxial measurement cell that simulates an oil storage tank. Frequency-domain electromagnetic sweeps were transmitted and received through coaxial cables connected to a vector network analyzer (VNA). The signals were processed using the Inverse Chirp Z-transform (ICZT) algorithm to derive spatial fluid composition profiles, validated through material balance calculations. This work was presented at the SPE Canadian Energy Technology Conference and Exhibition (March 12–13, 2025), article number SPE-223992-MS.

Key Takeaways

• Successfully mapped one-dimensional fluid composition profiles in real time.
• Achieved material balance errors below 1%, enabling precise monitoring of rag layers as thin as 20 cm.
• Offers a cost-effective and environmentally friendly alternative for oil storage monitoring.

This novel sensing method has the potential to improve real-time water cut monitoring, benefiting oil field operators and processing facilities.