Study On Hot-Water Flooding Mechanism In Low-Permeability Heavy Oil Reservoir

The method of the heavy oil mining technology all of the world was reviewed in this paper, analyzing the principle、the screening methods、the successful instance and the existing problems of the steam stimulation, hot water flooding, CO2flooding, the conventional water flooding, on this basis, the heavy oil exploitation technology of low permeability reservoirs of San Tang Hu oilfield was analysed, determining the effective mining technology certainly。 The result of researching the mining methods of San Tang Hu oilfield shows that as for Mabei block recovery of San Tang Hu oilfield method, hot water is first and followed by steam stimulation and conventional water flooding, if the problem of CO2gas source is solved, immiscible CO2flooding can be adopted to improve oil recovery。The Xishanyaozu reservoir of Santanghu Oilfield include Niuquanhu、 Mabei and Xixiagou block, on the whole, belonging to the structural-lithologic complex sandstone reservoir with low porosity、low permeability and low pressure--typical "three low " characteristics。 According to the oil and gas control factors and the difference of reservoir characteristics, Mabei block is divided into Lake218-well block the Lake-219well block and Ma46-well block. The16wells’physical properties from Mabei Block Xishanyaozu reservoie were analyzed comprehensively, with the results that, the physical properties of Ma46is the best, belonging to a Sino-porosity and low permeability Reservoirs; Lake218and Lake219are basically the same, belonging to low porosity, low permeability reservoir and abnormal low-voltage systems. According to the analyzing data taken by the reservoir test oil of the Xishanyao Formation oil sample, the ground crude oil density of the the reservoir was acquired by the mean of the arithmetic average, the result is:Lake2180.884g/cm3; Lake2190.915g/cm3; Ma46block0.901g/cm3。 the heavy oil used by this subject came from the Mabei110wells, the dehydration crude oil viscosity45℃is492.1mPa· s, belonging to the heavy oil reservoir.Taking into account the actual condition of the Santanghu oilfield Mabei block, in order to improve the developing effect of the Mabei Block low-permeability heavy oil reservoir, the flow characteristics study、the reservoir sensitive experimental study and the hot water flooding experimental studies were carried out in the indoor, providing reliable basis for Mabei block to carry out hot water flooding. The reservoir sensitivity Experimental results show that:the velocity sensitivity damage of Mabei Block was weak to medium; the water-sensitive damage was moderate to strong, critical salinity of salt sensitive was7500mg/L; the Alkaline sensitive damage was weak, the critical pH10; the Acid-sensitive damage was weak. The Mabei block oil viscosity have the characteristic of shear-thinning properties, and the oil viscosity decreases with the temperature increasing. When the formation water went through the oilfield reservoir rock, there is no start-up pressure, in accordance with the Darcy flow characteristics; the formation oil wen through the oilfield reservoir rock,there is start-up pressure,not in accordance with the Darcy flow characteristics. Hot water flooding experimental results showed that:the anhydrous oil displacement efficiency and ultimate displacement efficiency of the hot water flooding both increased with the temperature increasing. So increasing flooding temperature is an effective way to improve oil displacement efficiency.45℃is the inflection point of the crude oil viscosity, therefore, it is recommended to control the oil field water flooding temperature more than45℃. Driving pressure increasing has little effect on anhydrous oil displacement efficiency, but the final oil displacement efficiency increased with the driving pressure increasing respectively. Improve the driving pressure is an effective way to improve the final oil displacement efficiency. Reservoir macroscopic heterogeneity has a greater impact on oil recovery.