Research On The Synergy Mechanism Of Plug Removal Of High Pressure Steam Injection Well Of Heavy Oil Reservoir

As an important resource,heavy oil accounts for a large proportion in the world.The characteristics of rocks and fluids in the heavy oil reservoir are different,during the steam injection,the injection pressure of steam injection well become high,caused by the changes of temperature,pressure,the properties of injection fluids and the formation fluids.The high injection pressure of the steam injection well severely restricted the development of the heavy oil reservoir.The materials and cores of early-developed reservoir are limited,especially for the unconsolidated sandstone reservoir,therefore,the study by the experiments such as physical simulation are difficult to carry out.One of the important problems is how to study the high injection pressure mechanism of steam injection well caused by different kinds of formation damages based on the limited materials,and apply the effective measures to remove the plugs.Meanwhile,for the properties of different kinds of plugs,the chemical methods are not very effective;the synergy of hydraulic pulse wave and chemicals was applied successfully in the field.However,the kinetic synergy between hydraulic pulse wave and chemicals were seldom studied.Therefore,developing the simulation theory and method for formation damages,suitable for the aforementioned reservoir,lay the foundation for the mechanism study of plugs removal caused by different kinds of plugs in the in high pressure steam injection well.A large number of fundamental experiments were carried out to investigate the major plugs in the aforementioned well,such as clay minerals and asphaltene.The influencing mechanism of different kinds of plugs were obtained.Specifically,the volume changes and transformation of various minerals,the asphaltene deposition and the asphaltene absorbed on the various minerals under different condition.Based on the limited two dimensional data from the reservoir,the three dimensional porous media containing various clay minerals and textures were reconstructed,and the accuracy of the model was evaluated in different point of view.On this basis,the materials from reservoir and the experimental data were combined by the three dimensional porous media.The process of formation damages under different conditions were first simulated by the three dimensional porous media,and the relations between different kinds formation damages and the injection pressure were studied.In order to enhance the efficiency of the plugs removal,the hydraulic pulse wave was combined with different kinds plug removal measures.Based on the multi-hydrogen acid acidizing model of sandstone matrix and the adsorption-desorption model of asphaltene,the synergy kinetic model of plug removal was established,and the synergy mechanism was studied.In conclusion,theory basis was established for the application of hydraulic pulse wave assisted with chemicals in the steam injection well in heavy oil reservoir.Meanwhile,the formation damage simulation method by the three dimensional porous media based on the two dimensional data from reservoir proposed in the present work provide a new way for the study of formation damages,furthermore,the study and application of digital core will be extended.