| High-pressure water injection and flooding technology has injected new vitality into the aging oil well,but it also caused a serious incident of unsafe water injection,such as excessive water pressure will lead to casing damage formation rupture and micro-earthquake.Based on the theory of particle collision,this paper analyzes the causes of formation fracture caused by high-pressure water injection in the past decade,taking dense residual oil?Oil particles?with high dispersion and local enrichment as the research object,a collision force model between high-pressure water?H2O particles?and Oil particles?impact model of H2O+Oil particles?and a safe water injection pressure prediction model were established.The project of predicting safe water injection pressure and the corresponding safety measures are provided through an example application,which greatly improves the safety and recovery effect of high-pressure water injection and flooding operation,and provides a new research direction for preventing and controlling unsafe accidents such as formation rupture.The content and innovation of this paper are as follows:?1?Construction of H2O+Oil particles.According to the characteristics of high dispersion and local enrichment of the dense residual Oil,the dense residual Oil are regarded as Oil particles,the high-pressure water of flowing through oil well,fissures,micro fissures,and gradually approaching the Oil particles are considered as H2O particles,the interaction between high pressure water?H2O particles?and dense residual Oil?Oil particles?in micro fissures was analyzed.Meanwhile,the micro collision force of H2O+Oil particles was connected with other forces on H2O?Oil particles in complex flow field,so as to make an in-depth analysis in predicting safe and reasonable water injection pressure.The researches show that the energy transfer of the reasonable and stable H2O+Oil particle collision force is a positive driving force for Oil displacement under certain conditions,and also a key factor for preventing accidents and maintaining a stable water injection power.?2?Collision mechanism of H2O+Oil particles.We establish the two-dimensional Cartesian coordinates,according to the angle between the direction of collision force and X,Y axis,the collision mode can be divided into linear collision and oblique collision,and the particle motion rule under different collision modes can be analyzed.The researches show that in different stages of the collision process,water and oil particles have different collision modes,different collision forces and different existence states,therefore,the degree of damage to the formation is different due to the difference of this force.According to the unsafe influence caused by the difference in collision force,feasible technology and management measures should be adopted to stabilize water injection pressure and prevent formation fracture and other unsafe events.?3?Based on the model of H2O+Oil particles collision force,the prediction model of safe water injection pressure is established.By comparing and analyzing a typical Oil well with the established prediction model and the traditional calculation model,it is concluded that it is more accurate to predict the safe water injection pressure based on the relationship between the collision force of H2O+Oil particles and the fluid pressure,which can improve the safety and production effect of water injection operation.The researches show that the collision pressure and temperature of H2O+Oil particles are regular.with the increase of pressure,the inter-particle collision force increases,the temperature and volume expand,the viscosity and surface tension of oil particles decrease,the contact area increases,and the mobility of oil particles increases,therefore,the inter-particle collision force continues to act,thus enhancing the formation disturbance. |
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