DBPapers
DOI: 10.5593/sgem2017H/15/S06.016

EFFECTS OF DOLOMITE AND CALCITE ON CRUDE OIL OXIDATION BY THERMAL ANALYSIS TECHNIQUES

M.A. Abaas, M.A. Varfolomeev, C. Yuan, D. Emelianov
Thursday 23 November 2017 by Libadmin2017

References: 17th International Multidisciplinary Scientific GeoConference SGEM 2017, www.sgemviennagreen.org, SGEM2017 Vienna GREEN Conference Proceedings, ISBN 978-619-7408-26-3 / ISSN 1314-2704, 27 - 29 November, 2017, Vol. 17, Issue 15, 125-130 pp; DOI: 10.5593/sgem2017H/15/S06.016

ABSTRACT

Air injection techniques (high pressure air injection and in-situ combustion) for enhanced oil recovery (EOR) have attracted extensive attention due to its low cost. Air injection can be applied in many candidate reservoirs including carbonate reservoirs that account for a great proportion of total oil reserves all over the world. Dolomite and calcite are the main minerals of carbonate reservoirs. Therefore, it is necessary to study their effect on the oxidation of crude oil as the oxidation reaction exactly occurs in the porous media of rock and it determines that if an air injection process will be successful or not.
In this study, the effects of dolomite and calcite on the oxidation behavior of crude oils were investigated by a thermogravimetry coupled with Fourier-transform infrared spectroscopy (TG-FTIR) technique. Three reaction intervals were observed from TG-DTG curves of pure oil: low-temperature oxidation (LTO), fuel deposition (FD) and high-temperature oxidation (HTO, the combustion of deposited fuel). However, with the addition of dolomite or calcite, the FD process in DTG curves disappeared and merged with high-temperature oxidation. This indicated that the existence of dolomite or calcite promoted the FD process and made the fuel formation and its combustion more of a continuous reaction process. Except for the influence on FD process, dolomite had a small effect on the entire oxidation process, only slightly shifted the HTO peak into a lower temperature. However, the presence of calcite significantly shifted HTO interval from 500-600 ℃ into 380-520 ℃, also greatly increased the total gas release amount, which means calcite exhibited an obvious catalytic oxidation effect, and thus significantly enhanced the efficiency of fuel formation and combustion. This implies that the presence of this calcite will be favorable for the application of an in-situ combustion process. These findings not only can help to evaluate the feasibility of an air injection process in carbonate reservoirs with different mineral content of dolomite and calcite, but also can provide another possible catalytic method for crude oil oxidation.

Keywords: air injection, crude oil, oxidation, dolomite, calcite