A horizontal well was drilled in the Ravenspurn North field to drain a thin gas column above the aquifer. The field has a significant variation in reservoir quality, with most of the wells requiring stimulation by hydraulic fracturing. The reservoir is formed from a stacked sequence of aeolian dune and fluvial sandstones with a wide permeability range. The horizontal well was chosen as an alternative to stimulation by hydraulic fracturing to avoid water production from the aquifer. The well was successful, flowing at higher gas rates than expected with no water production. Production, core, and production logging data were used to demonstrate greater than expected lateral heterogeneity in the field. The horizontal well was found to be appropriate for the very specific conditions found in one part of the reservoir; however, the overall development strategy of using hydraulic fracture remains the preferred technique.
The Ravenspurn North gas field is in Blocks 42/30 and 43/26 of the U.K. North Sea and is operated on behalf of the unit partners by Hamilton Oil Co. Ltd. The current estimate of gas initially in place is 2.1 Tscf. The field is 16 miles long by 3 miles wide and has been developed with three wellhead towers linked to a process and compression platform adjacent to one of the towers. First gas was produced in July 1990, and the plateau production period is planned to continue until 1996.