For Stranded Oil Reserves, Gravity Drainage is an recovery concept where drifts that serve as an Underground Drilling Platform are excavated below an oil bearing formation. Close-spaced wells are drilled up into the formation and oil is collected into a pipe manifold in the underground space. UOR wells are short, they do not require pumps, and they can be a smaller diameter, and this makes them less expensive. More of these inexpensive holes can be drilled closer together, so more of the oil will be recovered. The improved recovery from the oil field makes the economics very attractive. While each site is unique, ergonomic factors limit the depth at which a gravity drainage platform can be excavated, with a rough guide that these facilities can be built only to about 3,000 ft.