Quantitative Description Of Water Cone And Study On The Well Pattern Optimization In Bottom Water Reservoir

Oil in place is numerous in much domestic and foreign reservoir with bottom water, and there is great potential for enhancing recovery of bottom water reservoir. The recovery is low due to rapid water-cone breakthrough in bottom water reservoir. So how to control water coning and impove development effect by optimum utilization of bottom water efficiently is the imperative challenge in the filed. The study of distribution and size of remaining oil, by calculating dimension of water coning and water cone height, can guide pattern modification and scheme optimization during later stage of production.On the basis of previous literatures about water bottom reservoir, water coning models before and after water breakthrough are established by combining principle of statics with radial flow and spheroidal flow. And water coning shapes in water bottom reservoir without interbed are obtained. The regularity of factors affecting development effect is studied in univariate analysis by numerical simulation. Combined with multivariate statistical regression, the formula of water coning in bottom water reservoir without interlayer is set up. The effect of size and location of interlayer on water coning is analyzed because most of water bottom water reservoir contains interlayers generally.Likewise, the formula of water coning of horizontal well in bottom water reservoir without interlayer by numerical simulation and multivariate statistical multiple regression. At present most of domestic bottom water reservoir has been developed to later stage by vertical wells. To improve recovery, horizontal well is drilled when water cut reches a very high level. The relation of cumulative recoverable reserves and oil production within six years of horizontal well with sensitive parameters (oil viscosity ratio, oil height, spacing of vertical well, and anisotropy coefficient) is obtained. Horizontal well can be used in bottom water when the single-well recoverable reserve is larger than economy limit recoverable reserve. A series of plates are obtained to ensure minimum oil layer thickness, which is the thickness when gross output is equal to total input during development period. Finally, development programs included well pattern optimization and injection-production ratio and so on, are proposed.