H2S removal at downhole conditions using iron oxide nanoparticles

Resumo

The objective of the present work is the study of H₂S removal from heavy oil, using iron oxide nanoparticles in a controlled environment that simulates the pressure and temperature conditions of a reservoir and the aqua-thermolysis process during enhanced oil recovery with steam injection. Since molecular diffusion of H₂S plays an important role during the removal process, its measurement through experimental tests was also a major goal. The research divides into three stages: 1) preparation of nanoparticles; 2) diffusion tests, and, 3) H₂S removal tests. The procedure for nanoparticle preparation from a microemulsion and a metal precursor salt was successful in yielding nanoparticle sizes less than 100 nm. The diffusion coefficient of H₂S in heavy oil, measured in a stainless steel PVT cell, varied between 8.3 × 10^–9 and 8.9 × 10^–9 m²s^–1 over the range of test temperatures. Finally, over 65% of the H₂S was removed when 500 ppm of nanoparticles were used.