Study On Optimization Of Water Quality Index Range Of Injection Water In North Truva Oilfield

North Truva Oilfield is a carbonate reservoir located in the Caspian basin in central Asia.In order to better realize the effective conservation of reservoir energy and exert the purpose of reservoir development to the greatest extent,how to "fill well with water" has become a concern in the current oilfield development process.However,in the process of waterflood development,the substances contained in water quality will directly affect the injection amount of water and the development effect of reservoir.When there is a large amount of suspended matter in the injected water,filter cake will be formed at the injection site at the bottom of the well and in the porous media of the reservoir,which will block the pore throat and deteriorate the reservoir connectivity,thus reducing the reservoir's water absorption capacity and increasing surface water injection pressure.Due to the heterogeneity of the reservoir,the increase of heterogeneity will lead to the decrease of swept area in the process of oil displacement and the decrease of production due to the lack of energy in the reservoir.Therefore,it is very important to evaluate the injected water quality and optimize the indexes for the injection water development of North Truva oilfield.In the process of water injection development of North Truva oilfield,there are many factors that lead to reservoir damage and decrease of water absorption capacity,and the mechanism of action is also relatively complex.Therefore,the evaluation of injected water quality and the optimization of indexes are of great significance for the subsequent development of the oilfield.In this paper,the reason of reservoir permeability decline caused by injected water is analyzed theoretically,and the indexes of injected water are optimized.The basic process of reservoir damage is fully analyzed,and the damage of injected water to reservoir is divided into mechanical damage,chemical damage,biological damage and thermal damage.Through the indoor experiment design related,injection water were studied with the experimental results the indicators of formation damage,including the concentration of suspended particles and size,oil content,the size of the oil droplets,bacteria,corrosion products,such as research on effect of reservoir permeability,water injection system in different kinds of bacteria in water injection pipeline corrosion and the study of reservoir blockage,dissolved gas on water injection pipeline corrosion mechanism and experimental study.The surface optimization method was used to analyze the experimental results and evaluate the correlation of each index,and the key water quality indexes,such as suspended particle size,suspended particle concentration,oil concentration,dissolved gas content,and different types of bacteria content,were selected to obtain an optimal set of recommended water quality indexes,which were verified by experiments.In order to protect the reservoir,protect the water injection system equipment and develop the oil field better,the recommended standard of water quality suitable for the water injection development of North Truva oilfield was selected by combining the method of laboratory experiment research and theoretical research.