Stimulation Design and Evaluation of High Temperature SAGD Wells
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This thesis presents an experimental approach to design, perform, and evaluate stimulation treatments for SAGD producers completed with slotted liners. Heavy oil production from a high temperature sandstone reservoir declined due to the blockage of slots in horizontal liners. Blocking materials were mainly presented by silicon-based scales, migrated fines, and numerous iron species. Previously, wells were mainly treated by HCl and a high pH chelating agent. These treatments did not improve the production significantly but corroded liners even more. Three liners were pulled out from the wells. Blocking and scaling materials were collected from the slots and walls of these liners for analysis. The experimental process included static acid solubility tests using 15 wt% HCl at room temperature, SEM, and XRD analysis. Also, it was proved that hydrochloric acid is not an optimal solution for blockage removal in these producers. Additionally, organic solvent preflush proved to be an effective potential improvement in the treatment design. Oil sand samples were collected from the reservoir. The mineralogy of these samples was analyzed in detail. Organic matter was removed, and the rock samples were separated in sand, silt, and clay fractions. Presence of kaolinite, illite, muscovite, incomplete hydroxide interlayer smectite was proved by XRD, SEM, TEM, FTIR, and AAS. Also, interstratification of mica and kaolinite was observed. These results were used to make a decision concerning the choice of compatible treatment fluid. Seven stimulation treatments were conducted in five different wells using foamed chelating agent (GLDA). Flowback emulsion was separated and prepared for analysis which included ICP and GLDA titration. Additionally, the decomposition of GLDA at reservoir conditions was mimicked using aging cells. Decomposition products were identified using GC-MS and were found to be glutaric and aminodiacetic acids. Possible improvements in the treatment’s program and recommendations were formulated based on the obtained data. For example, the soaking time was reduced from 6 to 4 hours after the first treatment. Production data analysis proved the effectiveness of the treatment design. Overall, it was shown that only a systematic approach could be useful to design a successful treatment and achieve a positive impact.
Kudrashou, Viacheslau Y. (2015). Stimulation Design and Evaluation of High Temperature SAGD Wells. Master's thesis, Texas A & M University. Available electronically from