Research On The Nonlinear Porous Flow Models With The Quadratic Pressure Gradient For Complex Oil Reserviors

The porous flow theory of oil in underground reservoirs is the basis of reservoir development.Well-test analysis technology can provide technical support for the rational and efficient development of reservoirs.Nonlinear flow model in consideration of the influence of quadratic pressure gradient more accurately simulate the flow characteristics of underground oil than the traditional linear flow linear flow model;however,because the nonlinear flow theory about the quadratic pressure gradient is not sophisticated,carrying on the study of the nonlinear flow theory to reveal the real flow law is very significant for the rational and efficient development of the reservoir.This dissertation studied on the nonlinear flow theory model with the quadratic pressure gradient and the well-test analysis method for homogeneous reservoirs,multi-media reservoir,heterogeneous composite reservoir and multi-layer reservoir.The main works are as follows:(1)we respectively established and solved the nonlinear flow models with the quadratic pressure gradient for vertical wells,fractured vertical wells,horizontal wells and multi-stage fractured horizontal wells in heterogeneous reservoirs.we analyzed the sensitivity characteristics of model parameters on the type curves,such as the dimensionless quadratic pressure gradient coefficient,and discussed the nonlinear flow characteristics controlled by the quadratic pressure gradient.(2)we respectively established and solved the nonlinear flow models with the quadratic pressure gradient for vertical wells,fractured vertical wells,horizontal wells and multi-stage fractured horizontal wells in naturally fractured dual-porosity and triple-porosity reservoirs.we sutided the nonlinear flow characteristics that are controlled by the quadratic pressure gradient.(3)we respectively established and solved the nonlinear flow models with the quadratic pressure gradient for vertical wells,fractured vertical wells,horizontal wells and multi-stage fractured horizontal wells in N-zoned coposite reservoirs.we sutided the typical nonlinear flow characteristics.(4)we respectively established and solved the nonlinear flow models with the quadratic pressure gradient for vertical wells and fractured vertical wells in multiple layered reservoirs,we also sutided the typical nonlinear flow characteristics.We quantitatively studied the absolute deviations and the relative deviations between the nonlinear and linear model type curves for different quadratic pressure gradient coefficients under the conditions that the other model paprameters were the same.The following findings can be concluded:the type curves of the nonlinear model with the linear model are completely overlapped only in the pure wellbore storage stage;a larger quadratic pressure gradient coefficient causes a larger deviation of type curves between nonlinear and linear models;a larger production time also causes a larger deviation of type curves;the deviation of pressure curves is larger than that of the pressure derivative curves at the same production.At the end,we impelemented the example well-test interpretations using the real testing data from different wells and it was found that the skin factor and the reservoir penneability which were interpreted using nonlinear models were different from those using linear model.We can obtain more accurate parameters using nonlinear models to do interpretations because the nonlinear flow with the quadratic pressure gradient represents the real physical flow processes of oil through reservoirs.The research results of this dissertation may also provide guidance and reference for the study on the related nonlinear flow theory and applications in the other complex reservoirs at home and abroad.