An Economic Nano-Clay for Produced Water Barium Reuse to Precipitate Sulfate in Seawater

Abstract

The presence of sulfate ions in seawater represents potentials of scaling and formation damage problems in upstream applications when combined with high concentrations of calcium, barium or strontium ions often found in formation waters. It has been proved that barium ions are effective to precipitate sulfates as BaSO4. In oil production processes, underground barium ions will be produced out with formation water. Barium concentrations in produced water can be up to thousands ppm. It is economic and eco-friendly to reuse the barium to precipitate sulfates in seawater. This work provides a nano-sized aluminum hydro-silicate clay as the adsorbent to capture and release barium for reuse. The barium concentrations were determined using inductively coupled plasma mass spectrometer to evaluate barium adsorption/desorption efficiencies. In a specific barium reuse workflow, first, the adsorbents were immersed in produced water (barium ions from 100 ppm to 2,000 ppm) for the adsorption of barium. Then the nano-clay with barium was collected by centrifuge and immersed into a low sulfate water. The solutions were shaken for a certain time to release barium ions. After the nano-clay was removed, a high barium concentration water was obtained. Next the water was mixed with seawater to precipitate sulfates as BaSO4. After optimizing the adsorption/desorption of barium ions on the nano-clay at different pH conditions, it is found the nano-clay will capture barium in a weak base environment (pH 9~11) with adsorption amount 100% higher than at medium condition. And more than 20% barium ions on the adsorbent is released in a weak acid condition (3~5). The results also presented the nano-clay successfully collected barium ions from a barium solution of 500 ppm, and the collected barium ions were reused to precipitate sulfate as BaSO4 by mixing with seawater (sulfate > 4000 ppm, total dissolved solid > 50,000 ppm). This work intends to provide an economic nano-clay and an effective procedure to reuse barium from oil field produced waters to precipitate sulfate in seawater. The sulfate removed waters can be used for hydraulic fracturing, drilling fluid, waterflooding, and other oilfield applications. This work simultaneously treats the sulfate containing seawater and barium containing produced water with lower cost and more friendly impact on the environment.