Practice and Understanding of “Secondary-Tertiary Combination” in Reconstructing Underground Development System

During the high water cut and high oil recovery stage for the water flooding method, the characteristics including stability and specificity become prominent for the underground seepage field. The combination of secondary and tertiary recovery methods can integrate the advantages of seepage field reconstruction and multi-media flooding which can realize the cooperation management of recoverable reservoir and remaining potential. Based on the principle of rebuilding the efficient underground development system for mature oil fields, the controlling factors and mechanical mechanisms of seepage field during the water flooding method are systematically analyzed. Then, the synergistic effects of layer reorganization, well pattern redesign, and multi-media flooding on the adjustment control of the seepage field were characterized. The “secondary-tertiary combination” based reconstruction scheme of the underground development system suitable for the Gangxi-I district was designed. The generation, evolution, and stability process of the seepage field during the water flooding process for fault block reservoir were evaluated from both theoretical and practical aspects. By taking seepage velocity and residual potential as the main indexes, six types of potential units were classified, and five types of development adjustment directions were proposed. The combined technology modes of secondary recovery development, water flooding treatment, profile control and oil displacement, and tertiary recovery method were established which can “construct”, “supply”, “uniform”, and “change” the seepage field respectively. Through designing the “secondary-tertiary combination” based reconstruction scheme of the underground development system for Gangxi-I district, it is considered that layer reorganization and well pattern redesign are the foundation for the reconstruction of the underground development system, while multi-media (including water and chemical agent) flooding is the guarantee for the efficient operation of the underground development system. In this work, the “secondary-tertiary combination” based seepage field reconstruction design technology for fault block reservoir during high water cut stage was formed. Such technology can play theoretical and practical significance for similar domestic oilfields in realizing sustainable and efficient development under technical, economic, and social concerns.