Mechanism Study Of Enhanced Thermal Recovery In Horizontal Wells With Multi-composition Fluid In Heavy Oil Reservoir

The geological reserves all over the world is such abundant that the development of heavy oil reservoirs has been an important influence on oil and gas supply.Horizontal well is widely used in heavy oil thermal recovery process,but steam flow rate distribution along both reservoir and horizontal wellbore is in non-uniform,which usually lead to uneven flooding in the reservoir.Therefore,it becomes necessary to explore high-efficiency way of developing heavy oil reservoirs.In the article,based on the above problems of steam injection with the horizontal well in heavy oil reservoirs,the development mechanisms of the thermal recovery technologies of the multi-compound enhanced recovery efficiency are discussed.The article discussed this issue on the base of seepage mechanics,reservoir engineering,and reservoir physics with help of some scientific methods,say,numerical simulation and physical simulation.Through the design of the horizontal well scale model,a series of thermal recovery-horizontal well physical simulation experiments are carried out,and then steam injection profile along horizontal wellbore are studied.The effects of steam injection rate,injection fluid,injection mode,reservoir conditions and completion technology on steam injection profile along horizontal wellbore are analyzed through the sensitivity analysis experiments.Some measures are suggested to improve the steam injection profile.High temperature and high pressure oxidation tube is used to carry out the low temperature oxidation decomposition reaction of heavy oil by air injection,and the oxidation decomposition characteristics with different experimental temperatures,pressures and water saturations are summarized.By the PVT characteristics experiments of non-condensate gas and heavy oil system,solubility,volume expansion coefficient and viscosity of the oil-gas mixtures(including carbon dioxide and flue gas)under different experimental conditions are obtained.Slim-tube is used to carry out the dynamic displacement experiments and the development effects of heavy oil with different displacement methods are studied.Based on the similarity criterion of multi-compound enhanced thermal recovery technology for heavy oil horizontal well,a 3D model is designed.And then,series physical simulation experiments of multi-compound enhanced thermal recovery are carried out.The development effects and the characteristics of remaining oil distribution under different stages are observed and the development mechanisms of multi-compound enhanced thermal recovery are studied.According to the actual geological parameters of NB35-2 southern heavy oil reservoir,the numerical simulation method is used to study the develop process and the develop characteristics are recognized.The well pattern,injection mode and injection-production parameters are optimized.Based on this,the development effect has been studied to the selected pilot test area.The research results of this paper further improve the development theory of multi-compound enhanced thermal recovery with horizontal well in heavy oil reservoir,which is of great significance to guide its application in heavy oil reservoir.