Abstract The Harding Field was discovered in 1988 and lies within Block 9/23b, 320 km NE of Aberdeen, on the western flank of the Crawford Ridge. Appraisal drilling found a series of Tertiary accumulations along the Crawford Ridge, and, though most have an apparent element of stratigraphic trapping, a larger structural closure is possible. The present development comprises two heavy oil accumulations, Central and South, reservoired in massive sands of the Eocene Balder Formation. Deposited by mass flow processes, these clean and well-sorted sands have been further homogenized by post depositional remobilization and injection. There are seven horizontal producers in Central and three in South, with pressure support by water injection. Reservoir quality is exceptional, with permeability in excess of ten darcies and Pi's for the horizontal producers in excess of 1000 STB/psi. Production started in April 1996 achieving a plateau rate in excess of 90 MMSTBPD with 40% of the estimated 200 MMSTB reserves recovered in the first three years. Four smaller Tertiary satellite pools are presently under appraisal and development by extended reach drilling from the platform.