| Most of China’s oil fields have entered the middle and late stages of development,and the water content of produced fluids has reached more than 90%.The output of oil production sewage and the amount of surplus sewage are increasing.When sewage recirculation is used to treat oil production sewage,the accumulated fouling and other pollution along the route from the joint station to the injection well is serious,and the water pollution may cause secondary pollution.If the characteristics of the production fluid at the wellhead can be analyzed,the blockage law of the cores with different permeability rates can be studied,and the direct injection of water injection wells through the oil-water separation and treatment at the wellhead will not only have great economic and environmental protection value,but also the target block.Reservoir wastewater reinjection provides recommended indicators.Taking the medium-high permeability reservoir in the western part of Gudao as an example,the characteristics of wellhead production fluid were analyzed firstly,and the compatibility experiment of injection water and formation water and reservoir sensitivity experiment were carried out.Based on the analysis results of the characteristics of the production fluid,the core flow experiment was analyzed.The effect of different injection speeds on reservoir damage was studied.The permeability damage caused by suspended solid particle content,particle size and oil content to artificial cores with different permeability was studied.The main points of this article are as follows:The permeability loss value caused by suspended solid particles and emulsified oil at low injection rate is 7.8%and 9.5%higher than the high injection rate,indicating that the injection rate has little effect on the damage of the core.The larger the core permeability,the smaller the permeability loss.For the level of permeability,the larger the solid particle content and the larger the particle size,the more serious damage of the reservoir.Gas permeability is obtained by minimum curvature method interpolation,for 500×10-3μm2-7000×10-3μm2 reservoir of the suspended solid particles in the solution of the m2 injection chart and recommended limits,and according to the oil content and permeability loss value linear curve fitting,the gas permeability for 500×10-3μm2-7000×10-3μm2 of emulsified oil content in the reservoirs of recommended injection line,eased for the islands of the water quality index of west,to improve the effect of oilfield water injection has important guiding significance. |
