Reactive Transport Modelling of a Carbonate Reservoir under Seawater Injection
- Yisheng Hu (State Key Laboratory of Oil & Gas Reservoir Geology & Exploitation, Southwest Petroleum University) | Eric Mackay (Institute of Petroleum Engineering, Heriot-Watt University)
- Document ID
- Society of Petroleum Engineers
- SPE International Oilfield Scale Conference and Exhibition, 20-21 June, Aberdeen, Scotland, UK
- Publication Date
- Document Type
- Conference Paper
- 2018. Society of Petroleum Engineers
- 1.6.9 Coring, Fishing, 5.5.2 Core Analysis, 5 Reservoir Desciption & Dynamics, 5.8.7 Carbonate Reservoir, 5.1 Reservoir Characterisation, 5.5 Reservoir Simulation, 1.6 Drilling Operations, 5.1.4 Petrology
- Seawater injection, Geochemical reactions, Reactive transport model, Carbonate reservoir
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Produced water chemical compositional data are collected from a carbonate reservoir which had been flooded by North Seawater for more than 20 years, so there is an opportunity to analyse the large amount of produced water data collected, understand the brine/brine and brine/rock interactions and explore the impact factors behind them. In some publications, core flood experimental tests were performed with chalk cores or carbonate columns in order to make an understanding of possible chemical reactions occurring triggered by injected water with different composition (Seawater, low salinity water or any other brine). However, most of the time the laboratory conditions where core flooding experiments are implemented cannot fully simulate the real reservoir conditions. Therefore, in this study, with the help of the valuable produced water dataset and some basic reservoir properties, a one-dimensional reactive transport model is developed to identify what in situ reactions were taking place in the carbonate reservoir triggered by seawater injection.
From the perspective of reservoir mineralogy, calcite, as the dominant mineral in the carbonate reservoir, is relatively more chemically reactive than quartz and feldspar which are usually found in sandstone. Whether calcite is initially and dominantly present in the carbonate reservoir rock is dissolved under seawater flooding or not is the first key issue we focused on. The effects of calcite dissolution on the sulphate scaling reactions due to incompatible brine mixing and the potential occurrence of carbonate mineral precipitation induced by calcite dissolution are investigated and discussed in detail. The comparison of simulation results from the isothermal model and the non-isothermal model show the important role of temperature during geochemical processes. The partitioning of CO2 from the hydrocarbon phase into injected brine was considered through calculation of the composition of reacted seawater equilibrated with the CO2 gas phase with fixed partial pressure (equivalent with CO2 content), then subsequently the impact of CO2 interactions on the calcite, dolomite and huntite mineral reactions are studied and explained. We also use calculation results from the model to match the observed field data to demonstrate the possibility of ion exchange occurring in the chalk reservoir.
|File Size||2 MB||Number of Pages||24|
Collins, I. R., Duncum, S.D., Jordan, M.M., Feasey, N.D., 2006. The Development of a Revolution Scale-Control Product for the Control of Near-Well Bore Sulphate Scale Within Production Wells by the Treatment of Injection Seawater. Paper SPE 100357 presented at the SPE International Oilfield Scale Symposium, 31 May-1 June 2006, Aberdeen, UK.