Study Of Performance Evaluation By Polymer In Mid-low Permeability Reservoir

At present,during the mid-low permeability oilfield development,the core problem is the serious water logging which leads to the low injection efficiency,the low oil recovery and the poor development effect.Conventional development techniques can hardly solve these problem,so it is important to carry out the research of enhancing tertiary oil recovery in mid-low permeability reservoir.However,for mid-low permeability reservoir's medium character and development feature,there is no displacement agent that can enter mid-low permeability reservoir easily and displacement its oil efficiency.So researching the compatibility parameters of polymer molecule's size and core throat's size to find appropriate mid-low permeability reservoir displacement agent has important implications for enhancing oil recovery in mid-low permeability reservoir.This article uses two methods which are static light scattering and dynamic light scattering to measure the molecular weight and hydraulic size of different displacement agent,research the size of core throat in different core with different permeability by analyzing different pore characteristic parameters.Then this paper measures the resistance coefficient and residual resistance coefficient by experiment which come from polymer solution of different sizes being injected in cores,compares the distribution of polymer solution in core,evaluates if the polymer solution of different sizes can be injected and confirms the compatibility of dynamic hydraulic size and throat.At last,this paper simulates different reservoir conditions of different permeability,different temperature and different salinity,researches the displacement efficiency of polymers of different molecular weight by laboratory experiment and evaluates properties of the polymers.The results show that it is feasible to use polymer flooding in mid-low permeability reservoir,the bigger polymer's molecular weight is,the better oil displacement efficiency will be.The high molecule weight polymer whose molecule weight is about 15 million g/mol can enhancing oil recovery effectively in middle permeability reservoir.The super high molecular weight polymers whose molecule weight is more than 15 million g/mol can create a logjam easily in mid-low permeability reservoir whose permeability is lass than100×10^-3?m².