Research On The Reservoir Characteristics And Percolation Rule In Middle-later Development Phase, B Oilfield

Through a great deal of data of oil field, the core analysis test data and combining indoor model experiment, changes of reservoir characterization such as lithology, physical property, pore structure, and wettability are studied in B oil-field after long-term flood development and displacement of oil by water in a scale deposit injury condition. Then, variety regulation of reservoir characterization is obtained in long-term flood development. At the same time, also studied the injection of water as a result of the non-compatibility of scale reservoir conditions, and its impact on the water characteristics of flooding. Preliminary conclusions of the study are as follows:1. Changes in reservoir physical propertyAccordance with the logging data and core simulation of indoor water-flooding development measured in different periods of time before and after the experiment were analyzed, we can see that after the development of long-term water, reservoirs was increased total porosity, but the degree is little, a majority of permeability declined, but the relative higher permeability of samples increased significantly, so after long-term water erosion enhanced reservoir heterogeneity.2. Changes of reservoir porosity and pore structureThe type of the combination of pores did not change-mainly emposieu-intergranular space. Laumontite, intergranular corrosion porosity increased, the rate of face porosity slightly increased. Data analysis based on mercury penetration, we can see the proportion of increase and fall of displacement pressure is equal, median pressure is mainly increased, pore structure becomes more complexity after washing.3. Changes of interstitial material content and the grain sizeLog interpretation, slice and scanning electron microscopy test shows that after long-term water erosion, the content of chlorite and laumontite decreased. Slice shows that after the experiment significantly whisker chlorite reduced, laumontite dissolution have increased , the particle size analysis shows that particle sizeΦ> 4 of the very fine particles and clay particles decreased significantly.4. The change of wettabilityThe rate of water imbibition increased after long-term washing, and the hydrophilicity enhanced. In the point where water and oil have the same permeability, the water saturation increased.5. characteristics of water/oil displacementIn the core before and after the experiment relative permeability curve did not change significantly, mainly in a few of the experimental model of water injection the water permeability with increasing efficiency, displacement efficiency with a little fall ,and the water content increased faster.Trigger pressure of water/oil displacement was generally increased after eroding, displacement efficiency was declined and swept area was decreased under the same pressure condition of water-oil displacement, the major paths of water/oil displacement had not been changed ,but water breakthrough time accelerated and more cluster type residual oil appeared.6. crustation characteristics of the reserviorThe research discovers that crustation of the reservior were mainly barium sulphide and calcium carbonate, as a result of the non-compatibility of injection water and formation water. The permeability had decreased by 30% after 70PV crustation. Deposition was firstly generated in high capacity channels by using water of higher degree of mineralization, permeability was obviously decreased with the increasing of injection. Displacement efficiency was obviously decreased with a average index of 7.7% as a result of crustation of the reservoir.