Publications

Reservoir fluids containing H2S and CO2 are generally classified as sour. Sour field developments have always been considered as critical by operators. The lack of interest in producing these fields is mainly due to higher costs linked to the use of special alloys, HSE issues, additional treatments and technical difficulties. In recent years, an increase in the energy market demand has shifted the oil Companies attention to develop also the most contaminated and sour fields (containing up to 30% H2S). Nowadays, all the major oil companies are moving to deepen their knowledge on different technologies for sour reservoir exploitation. Eni has mainly focused its attention on techniques which aim to achieve bulk removal of the sour components. This paper presents two different H2S bulk removal technologies: the first process, HYSAC (Eni patent), is a physical absorption process exploiting the tendency of condensates to absorb H2S, the second one is a gas permeation process. This paper presents the operating results of two HYSAC Italian installations: a pilot plant, treating a gas stream of 80 Ndm³/h containing 16% of H2S with C-compound liquids as solvent, and a condensate treatment plant installed on a FPSO treating sour gas with 0.94% H2S. At the moment, process simulation for a field producing 15 MSm3/d of rich gas containing about 30% H2S, 10% CO2 with HYSAC technology has been carried out. Eni built also a membrane pilot plant for H2S bulk removal. The plant treated about 3000 Sm³/d of sour gas (up to 40000 ppm H2S, up to 15% CO2) giving promising results. In order to validate the results for the Membrane application, Eni is developing a membrane commercial demonstrative plant.