Determining the Source of Low Level H2S Using Novel Sampling Techniques

As operators drill deeper into higher pressures and temperatures as well as begin exploiting resource plays such as gas shale and liquid rich shale, the concentrations of gas contaminants such as H2S and CO2 become more and more important, especially in prescribed low cost developments. To understand the source of H2S, sulphur isotope mapping of pyrite, organic sulphur, anhydrite and H2S is crucial. This paper discusses a case study of a discovered field where low level H2S (25-40 ppm) is present in the hydrocarbon accumulation. Proper planning and novel techniques for the sampling of the reservoir fluid, preservation of the H2S and analysis of the Sulphur-34 values for H2S are described along with the business impact of the results.