Yang Bottom Water Coning Model Analysis And Improvement

Bottom water reservoirs exist widely and their reserves play an important role in China. The oil bearing area of bottom water reservoir is in contact with bottom water entirely, so, the depleted energy due to development can be supplied by the bottom water during the development of bottom water reservoir. On the other hand, the existence of bottom water will bring serious water coning problem to production wells. Furthermore, it will lower the oil recovery and run the risk of increasing operation costs. In order to develop bottom water reservoir more reasonably, and control bottom water coning effectively, deeper research should be carried on to study laws of bottom water coning. The method of combining reservoir engineering with numerical simulation is used to analyze and improve Yang's bottom water coning model in this thesis, and the application range of Yang's model is discussed. The following results were achieved through this research:1. It is concluded that Yang's model is essentially a type of semi log water producing curve model and water drive curves of A&B type are included in Yang's model. Furthermore, the application range of Yang's model is studied. By comparing Yang's model with water-cut raise curve of S type, the conclusion is drawn that wells which satisfy water-cut raise curve of S type will satisfy Yang's bottom water coning model.2. The parameter C which is used to correct water-oil ratio (WOR) is considered as a constant in Yang's model. Nevertheless, the result by this thesis shows that the constant C is influenced by some reservoir parameters, such as k_h and h. And their changing laws can be sorted into two: one is that C changes gradually with parameters such as h; the other is that C changes suddenly with parameters such as q_t. It is pointed out that sudden changes of C show the type of bottom water coning is changed.3. The regressive method for parameters of Yang's model when the parameter C changes are proposed.4. Yang's model is extended to rectangle reservoirs and corresponding statistical calculation formulas are achieved. Moreover, Yang's model is extended to 3D anisotropic reservoirs and the 3D water coning characteristics are studied under this situation.5. The application scope for Yang's model in the fractured dual porous media is studied. For the media with dual porosity & single permeability, the matrix affects thelaw of water production less and Yang's model is applicable on most conditions; and for the media with dual porosity & dual permeability, the low flowing ability in the matrix is required.6. In order to simulate the water-oil contact behavior more effectively during water coning, grid-size away from the wellbore should not be too large.