Produced Water Treatment with Membranes for Enhanced Oil Recovery in Carbonate and Sandstone Reservoirs

摘要

The research is focused on determining the technical performance of membranes for treating and reinjecting produced water (PW). Ionic composition of pre-treated PW containing 90,000 ppm total dissolved solids (TDS) is manipulated by membrane separation and reinjected as smart water in carbonate and sandstone reservoirs. Nanofiltration (NF) membranes coupled with reverse osmosis (RO) membranes are tested in this research. TDS of less than 5,000 ppm with negligible divalent ions is defined as Smart Water for sandstone reservoirs. High divalent ion concentrations with TDS typically above 10,000 ppm compose Smart Water for carbonate reservoirs. The performance of NF membranes at different pH of PW is evaluated at various pressures. An economic analysis is performed for different combinations of membranes with TDS of 90,000 ppm as reference. A combination of two NF membranes are used to produce Smart Water for carbonate reservoirs. The power consumption is calculated at 0.37 kWh/m3. PW reinjection in sandstones with TDS of 5,000 ppm require either the use of permeate from RO or supplying fresh water by other means for diluting permeate from NF. A power consumption of 14.8 kWh/m3 is calculated for the combination of two NF membranes and RO for Smart Water production for sandstones.