Identification Of The Dominant Flow Channels For Waterflooding Sandstone Reservoir

At present, waterflooding development of sandstone oilfield is the most common way of reservoir development. With the continuous development of water flooding, the oilfield has entered high water cut stage. Due to long-time waterflooding during the reservoir development, reservoir pore structure will have a great change. The imbalance of hydrodynamic field as well as the differences of permeability anisotropy and oil viscosity lead to injected water along the dominant channels with high permeability and high water which makes original pore throat radius and permeability enlarge with inefficient or ineffective injected water circulation to form the large pores namely the dominant flow channels. The presence of such dominant channels will bring tremendous pressure for oilfield development and lead to lower recovery making production costs rise and economic benefit decline. Therefore, it is imminent to research and identify the dominant flow channels. The dominant flow channels can not only sharpen contradictions between the layers with inefficient or ineffective injected water circulation, but also make production increase measures difficult to implement. Thus, the study of the dominant flow channel identification helps to improve recovery and waterflooding effect as well as has important practical significance to the water plugging for the profile.This paper takes Ma block 20 as an example. In September 1973, Ma block 20 was officially put into development. Since 1973, it has experienced four development stages including basic well pattern implementation stage, hierarchical system adjustment stage, comprehensive adjustment stage and local tapping stage. Currently, the block has already been in "double high" depth development stage. According to long-term water development and geological features of Ma block 20 in Liaohe Oilfield, analyze presented characteristics of the flow channels during the waterflooded process and reservoir heterogeneity which is the fundamental reason for the formation of the dominant flow channels. By analysing the performance characteristics of the dominant flow channels in the dynamic production, electrical property, static state and other aspects, determine the dominant flow channels location to guide waterflooding oilfield and large pore blocking. It provides a reliable basis for dominant flow channel study in other high water cut reservoirs.In Ma block 20, due to the oil multi-layer segments, long oil segments, permeability differences in different sandstone group and years of water development, the plane and the layer contradiction is prominent, reservoir flooded is serious and fault block contains multiple high water-cut wells. Based on geology, core analysis, logging, testing, drilling, logging and other information of Ma block 20, this paper uses multidisciplinary knowledge and technology as well as integrated analysis and judgment method to analyze the cause and criterion of dominant flow channels. Moreover, it has summarized lithologic, physical, microscopic and waterflooded characteristics of the study area. Calculated models of evaluation parameters such as porosity, permeability and pore throat radius have been established. 125 wells were interpreted. Porosity and permeability static parameter values of each well has been gotten and normalized. Combined with dynamic production data, the production data was analyzed and compared deeply. Finally, dynamic production constraints porosity and permeability static parameters to establish a reliable reservoir model of three-dimensional properties. In seven sandstone groups and 24 small layers of Ma block 20, the vertical and horizontal distribution of dominant flow channels has been deeply studied to find out the vertical and horizontal distribution providing a basis for deep flooding blocking objects clearly and preferable flooding system.