Abstract:The reservoir heterogeneity of offshore oilfield is very serious, and the residual oil still exists between and within layers after water flooding, which is difficult to be displaced efficiently. However, in order to maximize the oil displacement effect of reservoir, the pattern of non-equilibrium chemical flooding, which is suitable for offshore oilfield, is proposed in this paper. Aiming at the interlayer, intra-layer, plane and micro-heterogeneity, this technology adopts the corresponding unsteady, non-contiguous, dispersed and asymmetric technical means, in order to achieve the goal of vertical and horizontal equilibrium displacement. Furthermore, its field trial in offshore J oilfield has been carried out. Results show that, the water cut of one central well decreased from 84.6% to 70.2%, and the daily oil production increased by 70%; and the water cut of the other central well decreased from 96.1% to 88.0%, and the daily oil production increased by 173%, which both have achieved remarkable technical and economic results. Therefore, its feasibility and validity has been proved by the field application, and it is suitable for the reservoir fluid properties and development characteristics in offshore oilfield. As a result, the non-equilibrium chemical flooding pattern is the development direction of enhancing oil recovery in offshore oilfields.