Research On The Physical Properties And Changes Of Chang-6Reservoir In Hujianshan Oil Fieled

Because of the changes of strata pressure and temperature, brushing of injected water and aseries of measures in the procedure of long-period waterflooding in an oilfield, the propertities of thereservoir may have changed obviously. In the future, these changes will affect the implementationabout adjustment on development programs and optimization measures. This paper studies thechanges in the Chang-6reservoir characteristics about porosity and permeability, pore structure,sensitivity and the wettability after the water flooding, by combining indoor model experiment.On the basis of the clay minerals analysis，sensitivity experiments were done.The overallcharacteristics of the Hujianshan block included:the flow rate sensitivity in initial stage is weak;water sensitivity and salinity sensitivity in initial stage are weak, after water flooding watersensitivity is almost unchanged, but salinity sensitivity changed slightly; stress sensitivity is strong.According to the comparative analysis of the physical properties in different periods of timebefore and after the experiment,we found that the porosity and permeability of the reservoir havechanged,the permeability is rather changeable. After long-term water injection, the average radius ofcommunicating pore, the radius of flow structure and the medium radius have raised by analyzingproduced water, the results show that: the salinity of produced water has increased; the content ofK++Na+, Ca2+, Mg2+and Cl-has increased, but the content of HCO3-,CO32and SO42-has reduced.This phenomenon shows that the injection of water reacted chemically and physically withformation water or rock mineral in the cores, and filthy may generate in this strata.It is obtained by displacement efficiency factors experiment that displacement efficiencyincreases with the increase of injected water volume, but after the injected water reaches a certainvolume, the increasing extent is small. The wettability of the reservoir changes from slight water wetto strong water wet.The objectivity understanding and evaluation on changes of reservoir and percolationcharacteristics in Hujianshan oil fieled can be used as reasonable basis for water plugging and profile,optimizing water injection and adjusting development plan of oilfield.