Determination Of Irreducible Water Saturation And Its Application In Daqing Fuyang Oil Reservoir

In recent years, with the increasing demand of petroleum resources, development of low permeability reservoir has been paid more and more attention. Fuyu and Yangdachengzi reservoirs of Daqing oilfield belongs to such typical reservoir of low permeability, low porosity and low permeability, most of which need fracturing to put into production. Before fracturing,test oil well often produce no water, causing difficulties to qualitative water during drainage for production after fracturing, what is worse, some of the oil wells produce so much water that oil production is lower than before fracturing, unable to achieve the desired objective, so it is necessary to analyze changes of bound water in the formation and its effects on water production before and after fracturing.In this paper, the capillary pressure curve and relative permeability curve in different areas of Daqing Fuyang reservoir are determined by the semi permeable diaphragm method and non steady state method in combination, also, the bound water saturation of corresponding blocks and the critical water saturation are sure to be made, between which the relationship are analyzed in the further。Through indoor natural core simulation experiment,after fracturing fluid injected into formation, the law of variation of relative permeability and water saturation in the condition of fracturing the size of different crack in the formation show that the fracture has the certain influence on the cracks which have certain influence on bound water and critical water saturation that the larger the crack size is, the greater bound water and critical water saturation value is; results of analyzing the micro flow characteristics of reservoir show changes in the underlying the movable water is the main reason of producing water in oil well after fracturing in Fuyang reservoir.The results show that the fracture due to the existence of cracks after increasinge mobile water saturation is fu Yang after the fracturing of the main causes of the well water.The results provide a theoretical basis for qualitativing water after fracturing, having important practical significance on shortening the test cycle and accurately evaluating well productivity.