Identification and evaluation of polymers for EOR in high temperature, high salinity carbonate reservoir conditions

Abstract

Polymer flooding is a well-established chemical EOR technique. However, its application in high temperature and high salinity carbonate reservoirs is still a challenging task due to the unavailability of polymers which can withstand these reservoir conditions. Candidate polymers must provide the required rheology at low polymer concentration, be thermally and mechanically stable, and result in a manageable adsorption on the reservoir formulation. A polymer screening study has been conducted on a series of polymers, to identify the most suitable candidate that can tolerate these harsh reservoir conditions. Initially, a polymer screening study has been conducted through rheological measurements on a series of polymers to identify a polymer which can withstand high temperature and high salinity conditions followed by mechanical and thermal stability, filterability, dynamic adsorption and injectivity testing as a screening criterion for polymers in EOR operations. Amongst the tested polymers polyacrylamide based co- and ter-polymers showed reasonable temperature stability but very poor salinity tolerance. On the other hand, Schizophyllan a polysaccharide showed shear thinning behavior with excellent thermal stability and salt tolerance. Long term thermal stability of Schizophyllan was also conducted at a temperature of 120 °C and salinity up to 201.6 g/l under anaerobic conditions for over eight months and no significant viscosity loss was observed. Schizophyllan shows good injectivity on cores of permeability more than 30 mD. In addition the mechanical stability and filterability of Schizophyllan are also discussed. Dynamic adsorption of Schizophyllan has also been studied. Dynamic adsorption on cores of different permeabilites (3-163 mD) was found to be low in magnitude (7-48 μg/g). Identifying thermally stable, salt-tolerant polymer with high thickening efficiency, low adsorption, good injectability in carbonate reservoirs, and with promising recovery efficiency is a major step towards the application of polymer flooding in high temperature, high salinity UAE carbonate reservoirs.

Date of Award	2015
Original language	American English
Supervisor	Saeed Al Hassan (Supervisor)