| This subject is from the special major national science and technology research project (The4th subproject, Developing Software and Application of Oil-gas Pool-forming Process Simulation of the Fine Demonstration Project of BoHai Bay Basin DongYing Sag Exploration Mature Area (No.2008ZX05051)). This project was executed by Sheng Li Oil Field Group and China University of Geosciences and the Institute of Geological Information technology (China University of Geosciences). This paper was written mainly to study the techniques and methods about the simulation of hydrocarbon-expulsion in oil-gas pool-forming simulation, and in order to promote the simulation accuracy, it combined hydrocarbon-expulsion simulation with high pressure physical property parameters.As an advanced technology,3D oil-gas pool-forming simulation has very important meaning in taking geological knowledge, lowering the risk of oil-gas exploration, as well as increasing the benefit of exploration, therefore, it is being paid attention to at home and abroad increasingly, and huge investment was paid for its development.3D oil-gas pool-forming simulation is consisted of geological simulation, thermal history simulation, overpressure history simulation, hydrocarbon-generation history simulation, hydrocarbon-expulsion history simulation; migration gathered history simulation and3D visual display of each simulations modules. Among these modules, hydrocarbon-expulsion history simulation not only valuable in studying the process of hydrocarbon-expulsion and its result, but also important to the calculate accuracy of the whole simulation.As a result of the complicate theory, at the moment, people are only knowing a little truth of the actual process of hydrocarbon-expulsion underground, what we can do is just conducting related experiments, and extracting useful information in the data of research area. Basing on this, we can establish relating algorithm model, then realize the simulation by computer technology. These models mainly include compaction hydrocarbon-expulsion model, episodic hydrocarbon-expulsion model, diffusion hydrocarbon-expulsion model, stage-by-stage hydrocarbon-expulsion model and threshold hydrocarbon-expulsion model. And all of these models are useful in a certain extent. But either of them has a few defects, on the one hand none of them can stand for the actual hydrocarbon-expulsion, which means no one can be commonly used; on the other hand, though every model include the calculation of high pressure physical property parameters that contained solution of gas-oil ratio, volume coefficient and density etc., some of these parameters cannot be calculated perfectly, and there has no computing method about these parameters in most hydrocarbon-expulsion models. Aiming at these two questions, the main research contents of paper are:1. Studying on the importance and acquisition method of high pressure physical property parameters in hydrocarbon-expulsion simulation model. On account of system dynamics theory and relating hydrocarbon-expulsion theory, with high temperature and high pressure for conditions, studying the impact and method of every high pressure physical property parameters in hydrocarbon-expulsion. On this basis, searching high accuracy calculative method or relating empirical formula about every high pressure physical property parameters in hydrocarbon-expulsion model.2. Studying and comparing these hydrocarbon-expulsion modules that have been realized by others, and selecting appropriate module, then improving the module by putting the calculation of high pressure physical property parameters in it. Furthermore, by programming to realize the improved model. Finally, comparing the simulation results with the actual results of the research area, analyzing the accuracy of the simulation results.In this paper the technical route is:1. Searching and reading papers which have relation with high pressure physical property parameters, analyzing the meaning, acquisition methods and calculative methods of each parameter. Through analysis, in the formation, relevant high pressure physical property parameters of natural gas include:relative density, compressibility factor, volume coefficient, isothermal compressibility, viscosity and so forth; relevant high pressure physical property parameters of crude oil include:density, viscosity, volume coefficient, solution of gas-oil ratio, etc.:relevant high pressure physical property parameters of water include:mineralization, the solution of gas in water, volume coefficient, compressibility factor and viscosity etc.2. Searching and reading papers which have relation with hydrocarbon-expulsion, analyzing the characters of each hydrocarbon-expulsion model, selecting the appropriate model as the base model. The hydrocarbon-expulsion models include: compaction hydrocarbon-expulsion model, episodic hydrocarbon-expulsion model, diffusion hydrocarbon-expulsion model, stage-by-stage hydrocarbon-expulsion model and threshold hydrocarbon-expulsion model etc.Through the above analysis and research, this paper made the following main achievements and progress: 1. By studying on every high pressure physical property parameters, with temperature and pressure as the main changing conditions, combining with hydrocarbon-expulsion theory of hydrocarbon source rocks, then summarizing the relevant parameters are:the relative density of natural gas, volume coefficient of natural gas, the density of crude oil, volume coefficient of crude oil, solution of gas-oil ratio, mineralization of formation water, volume coefficient of formation water, solubility of gas in water. And researching the calculation of each parameter.2. Through studying the calculative theory and method of each hydrocarbon-expulsion model, basing on hydrocarbon-expulsion theory, made the stage-by-stage hydrocarbon-expulsion model as the base model, adding the calculation of high pressure physical property parameters in the model, so as to making the calculation process accord with actual situation in the formation fluid.3. Basing on geological model that constructed by corner-point grid model, by using IDL programming language, realizing3D hydrocarbon-expulsion simulation in oil-gas pool-forming simulation software. Finally, comparing the simulation results with the actual results of the research area, analyzing the accuracy of the simulation results.The innovations of this paper are:1. Adding the calculation of high pressure physical property parameters into hydrocarbon-expulsion simulation, so as to improve the simulation precision. Due to the lack of high pressure physical property parameters calculation in hydrocarbon-expulsion simulation, basing on the analysis of relevant high pressure physical property parameters, adding the calculation of high pressure physical property parameters that used in reservoir calculation, into hydrocarbon-expulsion simulation, so as to improve the precision of simulation.2. Improving the calculation of saturation about oil, gas and water in stage-by-stage hydrocarbon-expulsion model, and adding the calculation of high pressure physical property parameters into3D stage-by-stage hydrocarbon-expulsion model, designing3D stage-by-stage hydrocarbon-expulsion model with the calculation of high pressure physical property parameters in3D geological model.Now the research and results obtained in this paper have been successfully applied in the national major projects oil-gas fields and coalbed methane development technology "the fine demonstration project of bohai bay basin dongying sag exploration mature area", to be a part of "3D oil-gas pool-forming simulation and evaluation software system", as well as being applied in dongying sag NiuZhuang-WangJiagang mature exploration area. Finally, by comparing the simulation results with actual studying results of each hydrocarbon source layer in research area, certified that this improved method are more accuracy. |
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