Development and Performance of an Eco-Friendly Cross-Linked Polymer System for Water Shut-Off Technique

Abstract

Abstract Excessive water production is a serious issue to be dealt with during oil production from reservoirs. The use of gel as the water shutoff agent has been widely reported in enhanced oil recovery (EOR) for the development of mature oil fields. Polymer gels are used successfully in many reservoirs all over the world, but the problem lies in finding the suitable and economical polymer for the harsh reservoir conditions of high temperatures and salinity. The organically cross-linked polymer systems are being widely used due to their greater thermal stability and their applicability over wide pH range. Many organically cross-linked polymer gels have been developed till date but most of them suffered setbacks due to their inefficacy at high temperature and salinity, carcinogenicity or non eco-friendliness. In the present work an eco-friendly organically cross-linked polymer system of Hydroquinone (HQ)/Hexamethylene tetramine (HMTA) cross-linked polyacrylamide (PAM) has been developed which is suitable for water shut-off. The gel formed by cross-linking HQ and HMTA with PAM is found to have high mechanical strength, form gels at high temperature of about 120°C and retain stability for long periods of time. The performance of this system has been studied both by bulk gelation as well as in-situ gelation techniques. The gelation temperature was varied from 85°C to almost 120°C to study the variations in the performance of the polymer system. The in-situ gelation study was carried out by means of sandpack core flooding. The present gel system is very efficient in water shut-off technique and can be applied in oil fields without much damage to the environment as both HMTA and HQ are ecofriendly with HQ being harmful to aquatic life to some extent. The performance and efficiency of this polymer system in an oil field has been judged from core flooding experiments.