Project Summary
This study (co-funded by ANLEC R&D) provides an account of the Otway Stage 2B residual saturation and dissolution test.
This is the first field test of this nature in the world and the study reports on its execution and summary of the data obtained from the field test.
The goal of the CO2CRC Otway Stage 2B project was to measure large-scale residual trapping of CO2 in an actual field project, using five different methods, then compare the methods and make recommendations. It was realised during design that substantial information would be collected on dissolution trapping also allowing for analysis of this mechanism.
Following a lengthy design period, the field test program for Stage 2B of the CO2CRC Otway Project commenced on 17 June 2011 and finished on 12 September 2011. All the planned components of the field test were completed, including the five methods for measuring residual trapping. Extensive high-quality data has been obtained throughout the program that allows detailed analysis within each method. The responses at each stage show that the injected CO2 was driven to residual saturation and was detected by each of the five measurement methods.
Key conclusions:
- Excellent quality downhole pressure data were acquired throughout the field program from the permanent gauges. The high permeability of the injection interval did not cause problems with getting a sufficient pressure response to give a good signal to noise ratio.
- Excellent downhole temperature data were also acquired. The instantaneous readout of downhole temperatures proved extremely useful in diagnosing operational issues at several stages.
- All three RST logs were run as intended. Current interpretation has residual CO2 saturation around 0.18 in the lower half of the perforated interval and around 0.23 (average) in the upper half.
- Fluid sampling using the U-tubes was completed consistent with the test plan. The noble and organic tracers were added to the injection stream as planned and were measured during production stages at concentrations that were more than sufficient for analysis.
- The organic tracer test shows the partial breakdown of the three parent compounds, as hoped.
- Sampling for the dissolution test, including the added methanol, was performed as intended.
- Although not primary objectives of Stage 2B, the test sequence provided the opportunity to further test microseismic monitoring and provide controlled releases of CO2 for atmospheric monitoring.
For more information on the Otway Project please visit the CO2CRC website:
