Reservoir Monitoring with the RST Tool
Transcript from Sumij Academy Presentation
Good morning and good afternoon. Welcome to the first appointment of this week at Sumij Academy.
Logging in reservoir monitoring. Today we are talking about and focusing on a special technique — the Reservoir Saturation Tool (RST).
The RSFT Pro reservoir circulation tools incorporate Pulsetron generator and dual detector spectrometry system to measure elemental concentration, including carbon and oxygen, and formation electron capture cross section sigma.
Oil volume is computed from the carbon-oxygen ratio (CO) determined through spectral analysis to eliminate any environmental bias. The resulting reserve estimate is comparable to that from core analysis.
Sigma and Formation Saturation
The sigma measure is used to determine porosity and differentiate between saline water and oil to calculate formation oil saturation where formation water is fresh.
Salinity-independent saturation is determined from the CO Rium measurements. A quantitative, mineral-based lithology is achieved by analyzing the elements measured by RCT2 spectral lithology.
Applications in Production Logging
Production logging tools provide answers during reservoir monitoring, particularly for advanced optimization of production and for monitoring reservoir volume.
Free Phase Logging and Water Flow
The PTP free phase or cloud metab tool identifies oil, water, and gas in wells at any deviation.
Water flow is monitored to locate and evaluate axial water migration behind pipe. The tool measures the velocity of water flow in wells and determines the timing of internal or behind-pipe cross flow between zones.
Logging in Deviated and Vertical Wells
The pelu face log velocity calculated by RC tools is used to determine the velocity of phases in deviated wells. This is applicable not only to vertical wells but also to highly deviated ones.
Principal parameters analyzed in reservoir saturation include the carbon dioxide ratio, water flow log, waterfall log, and gas-water flow logs.
Enhanced Evaluation and Real-Time Support
Enhanced evaluation methods include sigma and gas saturation logging options used for formation saturation. Rapid data evaluation is supported by onsite data processing and global teams.
Gamma values help track changes in reservoir lithology and fluid properties. Different responses from reservoir saturation logs highlight key aspects of saturation tools.
Interpretation and Diagnosis
These tools produce characteristic responses that can be interpreted under specific reservoir conditions. This is useful for diagnostics and understanding the behavior of water, gas, and oil phases in the reservoir.
One example shows how we can study the water zone, the hydrocarbon zone, and their underlying relationships.
Porosity and Pressure Variations
Another factor analyzed is the variation in total porosity and pressure during the first phase of extraction and throughout reservoir monitoring.
Changes in total porosity along the reservoir help guide decisions such as when to begin electrical fracturing or stimulation activities. Monitoring pressure variation is essential for prolonging reservoir life.
Stable pressure supports more effective porosity and better flow characteristics for gas and other fluids.
Typical Log Results and Digital Tools
Typical log results include three types: depu, water saturation, and sigma.
A Python-based web application is in development using simulated data for baseline sigma, VU, and SSU.
These tools are essential for reservoir maintenance and longevity. Pressure changes, for instance, can lead to pore collapse or volume reduction, and even subsidence phenomena in formations like sandstone or claystone.
Final Note
This type of operation is essential for long-term reservoir monitoring.
We’ll continue with our next appointment to explore additional techniques used in reservoir monitoring.
