Quantitative Study On Microdistribution Of Residual Oil Through CT Scanning

The research of microdistribution of residual oil is an essential part of during thedevelopment of oil-gas field as well as the strong guarantee of effective oil recovery. Thestudy on microdistribution of residual oil at pore scale plays a key role in developmentadjustment of reservoir and improving the present situation of exploitation.With the aid of CT scanning technology, this thesis extracts the microscopiccharacteristics of water and oil in the core model, on this basis, the paper establishes anquantitative method for characterizing the microdistribution of residual oil, in addition, studyof the influence factors on the microdistribution of residual oil is carried out. Its specificcontents includes: establishment of microscopic displacement and CT scanning experimentsystem, design and operation and the microscopic displacement and CT scanning experiments,acquisition of CT scanning images under different experiment conditions, pretreatment,interpolation and segmentation of CT scanning images, three-dimensional reconstruction ofcore models, research of the microscopic topotaxy between the pore structure and residual oil,establishment of the quantitative method for characterizing the microdistribution of residualoil, study of the influence factors-displacement pressure, injection pore volume, oilsaturation, core permeation and heterogeneous conditions-on the microdistribution ofresidual oil.The results are as follows. With the increase of displacement pressure, the residual oil iswashed by injected water more intensively. With the increase of injection pore volume, thetotal volume of residual oil decrease obviously while the number of residual oil increases. Theshapes of residual oil change from meshwork forms to multi-pore, single-pore and oil filmforms. The effectiveness of oil saturation is similar to injection pore volume, With thedecrease of oil saturation, the number of residual oil increases and the shapes of residual oil change from meshwork forms to multi-pore, single-pore and oil film forms. With the decreaseof core permeation, the number of microscopic pores decreases while their average sizeincreases, which decreases the number of residual oil, so as the contact area between oil androck. The amout of meshwork forms and film forms decreases in the higher permeable core.With the influence of heterogeneous conditions, the injected water rushes through the highpermeability formation, which leads to the increase of the liquid in the delivery end as well asthe displacement efficiency, the meshwork forms changes into other forms of oil largely. Inthe lower permeable core, producing degree of the oil is lower so that the proportion ofmeshwork forms is higher.