Developing a tight gas reservoir with high pressure and temperature
Based on input from A/S Norske Shell:
The 6406/9-1 Linnorm discovery in the Norwegian Sea was proven in 2005 and appraised in 2007. It contains relatively dry gas in a complex and challenging reservoir with high pressure and temperature. The gas also has a high content of CO₂ and H₂S. Today’s licensees are Petoro, Total, Equinor and operator Shell.
Comprising the Ile, Tofte and Tilje formations, the reservoir is of variable quality. It has some very good sand units (500-1 500 mD), but also large sections of tight sandstone (0.001-1 mD) with poorer quality which contain gas. Gas in place is estimated at about 90 billion scm, with roughly half of this in tight zones.
The project is now being studied to determine its technical and commercial feasibility. With the next decision gate due in late 2019, several possible solutions are being evaluated. These cover direct subsea tie-back to an export system, phasing into nearby host fields or a stand-alone development.
Opportunities for developing the gas in the tight reservoirs are being assessed. Possible well designs include not only various conventional and/or dedicated types, but also a mix of production wells in conventional and tight reservoirs. Hydraulic stimulation and multizone completion technology are being assessed.
Figure 3.5 Linnorm. Illustration: A/S Norske Shell.