Identification of Geological Forms Using Production Data Identification des formes géologiques en utilisant les données de production

Identifying the geological forms of channels, faults and boundaries of reservoirs on the basis of well-tests or production history is a tricky problem for oil reservoir engineering. Analytical interpretation models of well-tests are used in simple cases. In multiphase cases or those which present a certain degree of geometrical complexity, it becomes necessary to use fluid flow simulation models. In this article, we intend to solve a problem of form inversion associated with a two-phase oil-water flow model in which the aim is to identify the form and the position of geological bodies in a hydrocarbon reservoir with production data match. In identifying the form, two problems generally occur: the choice of representation of geometrical forms and the calculation of sensitivities. To calculate the gradients, mesh perturbation techniques exist in fields where finite elements are commonly used. In the context of structured meshes often used in reservoir simulation, the application of such mesh perturbation techniques is difficult. The method suggested is based on the calculation of sensitivities on the continuous problem in relation to the geometry of the various geological bodies. Such a geometry is defined through triangulation. The adjustment parameters are the triangulation nodes and the gradients of tthe objective function are calculated in relation to the displacement of such nodes. An optimization algorithm coupled with a polyphase flow simulator has been developed. It takes into account the geometrical constraints of the adjustment parameters and guarantees the regularity of the forms obtained. Several laboratory applications have been carried out. With the help of calibrated production data this leads to a better characterization of the form, the size and the position of the sedimentary bodies in particular: reservoir boundaries, position and size of the faults and thickness and width of the channels. L'identification des formes géologiques de chenaux, de failles ou de limites de réservoirs à partir des données de tests de puits ou d'historiques de production constitue un problème délicat en ingénierie de réservoirs pétroliers. Des modèles analytiques d'interprétation de tests de puits sont utilisés dans des cas simples. Dans les cas multiphasiques ou de géométries complexes, il est nécessaire de recourir à des modèles de simulation d'écoulement de fluides. Dans cet article, nous nous proposons de résoudre un problème d'inversion de forme associé à un modèle d'écoulement diphasique eau-huile et notre objectif est d'identifier la forme et la position