Research On Well-logging Evaluation Methods Of Water-Flooded Carbonate Reservoir

During development process of L oil-field, oil wells are seriously water flooded, coning direction of injection water is quite inhomogeneous, and waterflood sweep efficiency is low. All these problems leads to water production problems in some oil wells once they are put into production, low oil production and low production capacity, and reducing oil production.In order to prevent the water cut rise, slow down production decline, it is of urgent need to conduct a thorough research on the reservoir area, which includes finding out the relationship between water and reservoir, establishing qualitative identification method, the quantitative interpretation standards of water flooded reservoir, and the way the water coning and the relationship between reservoir discrimination model, and rapid judgment of water flooding condition for a new development wells reservoir, finding out the rule of reservoir water flooding and remaining oil distribution features, prediction of remaining oil, profile control water plugging, improving recovery factor, providing basis for adjustment of reservoir development scheme, etc.Lots of research on well logging interpretation of water-flooded sand-shale reservoir has been done at present, while the methodology of well logging interpretation of water-flooded carbonate reservoir is still not complete. Besides, Compared with water-flooded sand-shale reservoir, the influence of fracture on water flooding characteristics and residual oil distribution need to be considered in well logging interpretation of water-flooded carbonate reservoir.This paper takes L oilfield as the research object, the logging interpretation of water-out reservoirs as the core, combined with carbonate rock characteristics, considering the influence of the cracks in the process of water at the same time, from the perspective of logging established carbonate water flooded layer interpretation system research method, remaining oil distribution prediction for effectively in high water cut period to explore a new way.Due to the effect of a small amount of micro fracture of seepage in low water period, water cut rises very fast. According to core analysis data, most of the study intervals are pore type reservoirs, with a small amount of micro cracks. Therefore, first using qualitative and quantitative methods to interprete the pore type reservoir. (1 Qualitative methods:combined with dynamic production data analysis of lfogging data and accurate extraction of water flooded layer logging response characteristics, making qualitative template to divide water flooded layer.Through the inversion of the original formation resistivity and original formation oil saturation,the water flooded layer are qualitative identified. (2)Quantitative approach:through calculating three saturation, moisture content and oil displacement efficiency model is established, the quantitative division of water level, using the above method can effectively identify watered-out layer.Second, where the development of micro cracks with the method of qualitative comparison for watered-out interpretation, analysis of imaging data, coring well summarized conventional logging response characteristics of fracture development period, can effectively identify the microfracture development interval, the interval by cross-hole compared to achieve the purpose of the qualitative identification of water flooded layer.Combining all the methods above, the recognition of water flooded layer has a strong effect, achieve the requirements of the interpretation coincidence rate and can be widely used in production.