Compared with conventional onshore oilfields, offshore oilfields have problems such as incomplete well pattern, large well spacing, strong heterogeneity, and high crude oil viscosity. Conventional chemical flooding methods have limited ability to control and drive, and relying on a single chemical agent system cannot avoid fingering and channeling in the presence of dominant pores and fractures. In order to continuously and evenly development the reservoir, it is necessary to study the discontinuous chemical flooding technology with the purposeful alternate combination of multiple chemical systems as the core. Firstly, the static properties and flooding characteristics of chemicals such as gels, microgels and associative polymers commonly used in discontinuous chemical flooding in offshore oilfields are evaluated. The concept of reservoir displacement equilibrium degree is established by comprehensively considering the sweeping conditions of every sub-layers and the oil displacement effect of the sub-layers. Based on this, combined with the physical simulation experiment of parallel core flooding, a simulation study is carried out on the adaptability of discontinuous chemical flooding and the production status of sub-layers in the process of discontinuous chemical flooding. Finally, Combining the indoor physical simulation test results, a pilot experiment plan for discontinuous chemical flooding in offshore BZ oil field is formulated. The basic performance of the chemical system commonly used in conventional chemical flooding is obtained through the experiments, and the systems are divided into three levels: strong, medium and weak according to the adjustable flooding intensity, which provides necessary parameter support for the efficient use of the chemical in the process of discontinuous chemical flooding. Through physical simulation experiments, the design principles and application specifications for obtaining discontinuous chemical flooding equilibrium production are given, which can provide theoretical guidance for practical field applications. Since the discontinuous chemical flooding in BZ oil field, the effect of oil increase has been remarkable. The peak daily oil production of a single well has increased by 115%, and the maximum reduction of water cut is 15%, At the same time, the effective time is more than five months. Discontinuous chemical flooding in offshore oilfields is a new development method that combines multiple technologies to "relay" flooding. This technology can efficiently improve oil production speed and oil production effect in the whole process of oilfield development, greatly shorten oilfield development time, in the shortest time to obtain maximum yield and economic benefits.

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