The invention discloses a method for identifying water
logging grades of an oil reservoir by using a neural network analogue
cross plot. In the method, the conventional
cross plot technology is improved by a neural network
algorithm, so nonlinear identification and quantitative analysis functions of the
cross plot are realized, and a back propagation (BP) neural network
algorithm is used and the method comprises the following steps of screening object characteristic parameters, selecting
network structure parameters, training a neural
network model, testing the
network model, and establishing a neural network analogue cross plot
layout. The method specifically comprises the following steps of: according to various characteristics of oil, gas and water
layers in reservoirs, accurately selecting parameter samples which can best reflect the characteristics of the oil, gas and water
layers in the reservoirs from parameters calculated during
well logging or the
well logging curves relevant to oil and gas interpretation by a statistics method; selecting appropriate weight values and threshold values by the BP neural network
algorithm to establish the
network model, and training the model and checking errors; and judging the
fluid type or water
logging degree of the reservoir with the depth according to projective points of identification vectors which are obtained by
network output on a plane.