Sour Gas Injection Design Extends the Envelope in Kazakhstan

Presented at Annual Conference September 2005, WarsawPresented by Michael Block, Nick Amott and John LantermanSour Gas Injection (SGI) is expected to permit increased oil production without increasing unwanted sulphur production at the Tengiz field in Kazakhstan, operated by Tengizchevroil. The Second Generation Project (SGP) oil production rate can be increased without increasing the demand for sour gas treatment and sulphur forming by drying the associated gas and then compressing it to a pressure level suitable for reinjection into the reservoir. The SGI Compressor Island is a remote facility some 12km from the SGP plant and handles up to 275 MMscfd of sour gas, at 620 barg, for distribution to multiple wellheads for injection. Injection not only has the benefits listed above, but can also assist in maintenance of oilfield pressure above the bubble point to retain the gas in solution and, therefore, prevent gas formation in the reservoir as well as prolong the life of the field by reducing the rate of pressure decay. Compressing and injecting sour gas at these pressures and flowrates required a leading edge design in several areas: 1. Compressor selection and testing 2. Compressor Seal design and testing 3. Piping and Equipment Materials selection 4. Predicting field response and selection of optimal wellheads for injection This paper addresses each of the above issues, and others, in more detail.