ON THE MAXIMUM WIDTH OF OIL STRINGERS UNDER HYDRODYNAMIC FLOW CONDITIONS

An analysis is presented of the maximum thickness of a stationary buoy ant oil-mass, trapped under an angled incline, when subjected to hydro dynamic, surface tension and buoyancy forces. For high water-flow spee ds down the aquifer, with upward buoyancy forces dominantly combating hydrodynamic pressure, it is shown that the maximum oil thickness occu rs at about 60% of the length of the oil stringer measured from the up ward end. The length of the oil stringer then is roughly proportional to the square root of the oil-mass contained, as is the maximum thickn ess. For low water-flow speeds, in which buoyancy and surface tension are dominantly balanced (with only lesser contributions from hydrodyna mic pressure), the oil length is effectively constant, whereas the max imum thickness grows proportionately to the 3/4 power of the contained oil mass at low oil masses, and proportionately to the oil mass at hi gh mass values. As the water-flow velocity increases, the shaping of t he oil stringer shifts from the small ''bubble'' form to the long oil stringer form. Analytic formulae are given to provide approximate meth ods from which to estimate oil and gas accumulations under more comple x conditions.