(445b) A Modification to the Application of Orthogonal Collocation Method for Petroleum Reservoir Production

This article is prepared to investigate a good variable change for diffusion equation to combine with orthogonal collocation method (OCM) to supreme its applicability and eliminate the need for orthogonal collocation on finite element (OCFE). Furthermore, two synthetic cases of oil reservoir production are studied with this good variable change in both radial and spherical geometries, the effectiveness is proved. For the time domain Implicit, explicit Euler method and Crank-Nicolson Method are examined. Results showed that the problems are mostly sensitive to spatial discrete errors. Because of the suitable collocation point distribution in the space domain, good result is made with only a few points. The validation is made by comparison with a finite acting solution for long time and Ln-solution for short time after production. For 300 days the %AARD (percentage of average absolute relative deviation) is 0.5 for radial geometry and unsteady state conditions, moreover for the steady state condition the %AARD is 0.0000 for less than 20 collocation points. However, the improvement on spherical geometry was only fair. At last, the idea is applied on a two-phase plus unsteady state flow which is complicated and troublesome, therefore more attractive.