The Impact Of Formation Damage Upon Flow Units In Lithologic Pinchout Oil And Gas Accumulation With Reference To Huachi And Maling Oilfield In Ordos Basin

Based on the theory and methods of sedimentology, reservoir geology, mineralogy, exploitation geology, reservoir engineering and reservoir chemistry, the impact on flow unit of formation damage was studied in lithologic pinchout oil reservoir, taking Huachi Oilfied And Maling Oilfield As examples. The micro and macro, dynamic and static, and theory and practice were combined in the study. In the study the flow unit model was set up, the evaluation of formation damage was done, the displacement characters of oil by water under the reservoir injury were obtained, and the infection to flow unit was discussed. The mainly fruits are as follows:1.It is the fist time that the flow unit's seepage mechanism were studied with natural sandstone micromodels, and the flow unit that has been plot out was validated using seepage experiment with natural sandstone micromodels for the first time. The flow unit model should be close the true by the study method.2.The experiment of combined natural sandstone micromodles indicate that the condition of the water absorption and liquid production are similar when the flow units are same, the condition will be difference obviously when the flow units are different, and the difference will be increase as advancing of experiment. It represents that flow units not only in micro but also in macro control the flow characters.3.The waterflooding response of oil wells are relate closely to the abutment manner between the oil well and water injection well. When the flow units are same between the oil well and water injection well, the responding of oil well will come soon, and water breakthrough will come late. When the flow units are different between the oil well and water injection well, the responding of oil well will come late, and water breakthrough will come soon.4.The velocity sensitivity is weak in Mubo Yan 10 reservoir, moreover the critical speed is related to permeability, and the critical speed is generally low when the permeability is low. In fact, the velocity-sensitive injury in waterflooding will be stronger than the results of experiments for the salinity of injected water being higher in experiment than in practice, the water sensitivity is weak to middle, and the extent of water sensitive damage will be reduced when water salinity is increased. According to the experiments the extent of water sensitive damage will be reduced when the water salinity is increased gradually and the suitable salinity of injected water is 5-10g/l.5.Scale deposit affects permeability largely in Huachi Chang3 reservoir. The infection extent is relate to the commixed times of injected water and formation water, the more commixed times of injected water and formation water, the more falling extent of permeability. It represents that the scale deposit will be seriously in the layer with high permeability, fracture and the area near oil well bottom.6.The study were done for the first time by using natural sandstone micromodles under formation injury. The research represents that the entrance pressure will increased, the heterogeneity of pore structure will become stronger, the injected water will make bigger detours, and the sweep efficiency in micro and macro will decreased under reservoir injury, as the results the reservoir recovery efficiency is reduced.