Enhanced gas recovery by CO2 injection and sequestration : effect of connate water salinity on displacement efficiency

Abba, MK; Abbas, AJ; Nasr, GG

Abstract

As natural gas continues to gain widespread usage as a source of cleaner and efficient fossil fuel, while greenhouse gas emission is attracting environmental consequences, the need for a viable method to enhance gas recovery and curtail greenhouse gas emissions, is paramount. The technique of injecting CO2 for Enhanced Gas Recovery (EGR) is deemed one of the efficient methods for simultaneously storing man-made CO2 emissions and improving additional natural gas recovery from depleted gas fields, provided that the gas miscibility in situ (mixing) can be reduced. This can be achieved by a better understanding of the mechanisms of displacement and the factors that affect them, hence providing vital information for further studies aimed at a wider and robust field scale application and establish the economic viability of the process. Connate water saturation and salinities are vital properties of the reservoir and their influence on the displacement efficiency cannot be overemphasised. This experimental study determines the effect of connate water salinity, in sandstone samples, on the displacement efficiency during EGR. This study presents the first novel experimental measurement of dispersion of CO2 in CH4 as a function of salinity in consolidated porous media. A laboratory experiment depicting the detailed process of the CO2-CH4 displacement in sandstone core samples at a temperature range of 30-70°C and at a pressure range of 500-2000 psig, was carried in the investigation, at a CO2 injection rate of 0.25 ml/min to evaluate the displacement efficiency. The findings indicated that salinity of the connate water tends to decrease the dispersion of CO2 in CH4 at the stated conditions. This can be attributed to the increase in density of the connate water with increase in salinity, which occupies smaller pore channels within the porous medium. Also, grain diameter measurements were carried out from Scanning Electron Microscopy (SEM) images of the porous media using equivalent circle diameters to establish the characteristic length of mixing of the medium.

Citation

Abba, M., Abbas, A., & Nasr, G. (2017, November). Enhanced gas recovery by CO2 injection and sequestration : effect of connate water salinity on displacement efficiency. Poster presented at Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, UAE

• Presentation Conference Type: Poster
• Conference Name: Abu Dhabi International Petroleum Exhibition and Conference
• Conference Location: Abu Dhabi, UAE
• Start Date: Nov 13, 2017
• End Date: Nov 16, 2017
• Publication Date: Nov 16, 2017
• Deposit Date: Oct 4, 2018
• Book Title: Abu Dhabi International Petroleum Exhibition & Conference, 13-16 November , Abu Dhabi, UAE
• ISBN: 9781613995631
• DOI: https://doi.org/10.2118/188930-MS
• Publisher URL: https://doi.org/10.2118/188930-MS
• Related Public URLs: https://www.onepetro.org/
• Additional Information: Event Type : Conference