The Predicted Theory Model Study Of Organic Solid Precipitation In Petroleum Development

The organic solid deposition in oil and gas system has been a serious problem in the petroleum industry. The organic solid deposition would appear in all the producing and processing system, such as a reservoir, wells or surface lines. In recent years, along with the development deeply and broadly in the petroleum developing and processing, the research and resolution of the solid deposition is becoming the more urgent and outstanding especially in the process of gas injection for enhancing oil recovery. It is a more difficult to handle and very necessary research subject around the world. The research on the mechanism of organic solid deposition and thermodynamic model is on the preliminary exploration period in theoretical, experimental, technological methods and qualitative, quantitative mathematical description. As a result, it is necessary to do further research on the problems of the organic solid deposition in oil and gas system. After clarifying this problem, to establish an integral and practical thermodynamic model to describe the VLES rule and simulate the organic solid deposition on the base of liquid multiphase equilibrium thermodynamic principle, and then establish the organic solid phase predictive evaluation techniques during the oil and gas development process and the miscible displacement in gas injection. In this way, it can apply the evaluation methods for oil and gas development to guide its exploitation, production and engineering designation.The article applying comprehensively the study results in the past, the thermodynamic theoretical model of the organic solid substance is mainly described based on overall investigation and analyses about the situation in this field and the trend of the study is grasped. Mian achievements in the paper are as follows:On the base of sufficiency research on the oil-gas hydrocarbon systemic chemistry composing and the physical chemistry characters, we traverse the mechanism of the organic solid substance's deposition. Then we consider that the organic solid substance's deposition is a complex process of physical chemistry, which includes more than one single mechanism.Mechanism of the organic solid deposition directly influences the form of thermodynamic model. The article takes the theory of thermodynamic phase equilibrium as the method of studying deposition mechanism of the organic solids.Hypotheses of thermodynamic theoretical model are given based on analyzing multiphase equilibrium behavior and dissecting real physicochemical principles; the condition of the multi-phase thermodynamic equilibrium is discussed.The regular solution theory, the local composition model and Flory polymer solution theory is introduced as the foundation of the theoretical study. The unified mathematic model to describe VLS multiphase thermodynamic equilibrium with EOS and solution theory is put forward.A thermodynamic micellization model for asphaltene precipitation is presented considering the balance of resin between the surface of asphaltene colloid and in the solution on the basis of the deposition mechanism of asphaltene. The article has also improved the method of calculating multiphase equilibrium. It requires the solution of minimization problem only noce by Marquart method and provides phase number presenting at phase equilibrium, their quantities and compositions simultaneously.The article edited some application programs and some cases are conducted to verify the correctness and effectiveness of the theory and methods.Finally, through deep-going discussing the case in-practice, compared with the calculation and the theoretical study, the primary conclusions are made, some problems concerning with the successive study is suggested.