A new Kriging model based on water invasion unit numerical simulation

In order to scientifically and accurately characterize the change of water invasion front in edge water gas reservoirs, a new interpolation calculation method is developed. Based on the constructed water invasion unit numerical simulation model (WINS), the saturation tracking method between water invasion channels is improved by the gas–water two-phase flow equation. The dynamic result is the saturation, which is a constraint in the Kriging model estimate. Considering the reservoir static geological factors, the permeability penetration coefficient is determined by genetic algorithm inversion, and the weight coefficient of the Kriging model estimate is determined by the differential variation model. The most important innovation of the new Kriging model is that the constraint is considered in the water invasion front inversion. The model has many advantages. First, the problem of the rough characterization of the water invasion front is solved. Considering that the WINS only constructs the saturation distribution based on the data interpolation of the sampling points, the new Kriging model adds constraint points, which can more accurately characterize the non-equilibrium water invasion. Second, the Kriging method only considers the geological static characteristics, but the water invasion process is dynamic. The new Kriging model can invert the water invasion characteristic parameters at each time step, so as to define the constraint conditions. Third, we combine a genetic algorithm to consider the automatic fitting of the global characteristic parameters. Compared with the traditional method, we only adjusted the water invasion characteristic parameters to match the space-time line of the water invasion front, avoiding the overfitting situation.