Abstract
Severe fouling of crude oil and produced water treatment equipment of Mangala Processing Terminal (MPT) with elastic deposits has been observed after EOR polymer breaking through to the producing wells. Fouling by polymer containing solids caused the system bottlenecking impacting on crude production rates and deterioration of water quality for injection due to increase of total solids loading.
The objective of the study included developing the water treatment technology for removing the returned polymer, developing the pilot run for implementation of the technology and scaling up the process if the pilot shows success.
Crude processed at MPT is produced from Mangala, Bhagyam and Aishwarya fields which are located at the north-west part of India. Full field polymer flooding has been implemented in the Mangala field from 2015. Fouling of downhole and topside equipment with elastic deposits has been reported soon after polymer breakthrough the same year.
For reducing the fouling potential and solids loading, the concept of removing the returned polymer from produced water has been considered as beneficial.
Removal of polymer through the chemical coagulation was considered for developing. Extensive laboratory and bench testing have been carried out. Based on the laboratory results, the pilot was developed and carried out on the flotation equipment available at MPT.
In the laboratory and bench test for polymer coagulation, over 70% polymer removal was achieved with non-sticky flocks and minimal sludge. The tests also demonstrated reduced suspended solids, residual oil and filterability improvement of treated water.
The pilot run confirmed effectiveness of the chemical coagulation process to remove polymer. Polymer removal > 70% was observed during the pilot. Oil removal from produced water at 60-80% was seen. Cloud point of polymer remaining in water increased from 60°C to > 110°C indicating on the significant potential reduction of remaining polymer to precipitate from treated water.
The pilot results demonstrated on the applicability of the technology of chemical polymer removal at MPT and will be used for scaling up the treatment facilities.
Characteristics and Management of Produced Water in Al-Ahdab Oil Field
