Study of Calcium Carbonate Precipitation in the Near-Well Region Using 47Ca as Tracer
- Emmanuel Stamatakis (Institute for Energy Technology) | Are Haugan (Inst. for Energy Technology) | C. Chatzichristos (Inst. for Energiteknikk) | Athanassios K. Stubos (NCSR Demokritos) | Jiri Muller (Inst. for Energiteknikk) | Oyvind Dugstad (Inst. for Energy Technology) | Ioannis Palyvos (NTUA - School of Chemical Engineering)
- Document ID
- Society of Petroleum Engineers
- SPE Production & Operations
- Publication Date
- February 2006
- Document Type
- Journal Paper
- 33 - 39
- 2006. Society of Petroleum Engineers
- 5.1.5 Geologic Modeling, 4.1.5 Processing Equipment, 4.1.2 Separation and Treating, 4.3.4 Scale, 5.3.1 Flow in Porous Media, 4.2 Pipelines, Flowlines and Risers, 5.9.2 Geothermal Resources, 5.5 Reservoir Simulation, 1.8 Formation Damage, 2.4.3 Sand/Solids Control, 2.7.1 Completion Fluids, 5.6.5 Tracers
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Calcium carbonate scale formation during flow in porous media was studied using radioactive tracer technology; in a series of calcite scaling experiments in sandpacks, 47Ca was used as a tracer to monitor CaCO3 deposition. In these experiments, the induction time and the distribution of scale deposition were studied as a function of saturation ratio, temperature, flow velocity, the presence of Mg ions, and the type of packing material. The results show that the radiotracer method gives a fast response to scaling events. The technique is applicable for dynamic scaling investigations in any flowing system in porous media and constitutes a valuable tool for further studies of scaling mechanisms involved in processes occurring in a variety of systems (oilfield, geothermal, and desalination).
The formation of mineral scales from produced water/brines in oil/gas wells and pipelines constitutes an old but persistent problem for the oil industry. Lost production, formation damage, and operational problems caused by scale deposits cost hundreds of millions of dollars (U.S.) every year. To date, there is no available method for the prediction of the time of onset for scale deposition and pore blocking in the near-well zone. The only indications of scaling in the field (near-well zone) are the change in the well pressure drop and/or the reduction in concentration of ions, which are prone to precipitate (for instance Ca2+, Sr2+, Ba2+, HCO3-/CO32-, SO42-). However, when this kind of effect starts being recorded, scaling processes have already commenced. In addition, the extent of scaling in the formation around the well is virtually unknown, because only secondary effects can be recorded downhole or/and at the surface. Better understanding of scaling in the porous matrix of a formation is therefore requested.
We have recently developed a new method to study calcium carbonate precipitation in laboratory experiments using the gamma emitting tracer 47Ca (Stamatakis et al. 2005a). The advantage of this method is its high sensitivity for the onset of precipitation (short induction time) and its ability to visualize the scale distribution, which is not readily done with conventional methods. Furthermore, experimental simulation of the scaling potential in porous media (sandpacks) gives new insights of the actual extent of scaling in the formation around the well.
Several tests were carried out to test the method. In that respect, the radiotracer 47Ca is used to study CaCO3 precipitation in sandpack blocking tests.
|File Size||1 MB||Number of Pages||7|
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