A Study On The Special Phase Behavior Of Multiphase Fluid In Gas Reservoirs With High Sulfur Content And Formation Damage Caused By The Sulfur Deposition

With the increasing demand of the energy sources in the world, the development of high sulfur content gas reseivoirs becomes more and more important. However, the high sulfur content gas reservoirs have the complicated characteristics of special fluid PVT in high pressure, sulfur deposition, gas-liquid-solid translation and non-Darcy flow compare to the common gas reservoirs. This brings the server difficulty and huge challenge. Moreover, the fallibilities for production projects and dynamic predictions do harm to the engineering management, environment protection and society progress. The abroad attention was aroused by the tragedy of huge well-blowout on Dec. 23, 2003 and high sulfur content gas leak on Mar. 25, 2006 that happened in Luo jiazhai gas reservoirs in Kaixian of Chongqing, which gives the deep lessons to the study of oil & gas exploiting engineering. Therefore, the dissertation mainly studies the calculation of PVT physical properties in high pressure, the special fluid phase behavior, the prediction and correlation of the sulfur solubility and the damage caused by the sulfur deposition in high sulfur content gas reservoirs. The thesis belongs to the main harvest of state nature and science fund project.Based on the former experiment, the thesis using by the theory model associated with model applications includes the following contents. Based on the experiment, the methods are induced and summarized for calculation the PVT physical properties in high sulfur content gas reservoirs. The special phase behaviors for high sulfur content gas reservoirs are studied, which include sulfur dissolution and deposition, the sulfur freezing point, the sulfur phase behavior, the mixtures phase behavior of sulfur and pure hydrogen sulfide and the mixtures phase behavior of the sulfur and high sulfur content gas reservoirs. The dissolution and deposition of sulfur in high sulfur content gas reservoirs are similar to the dissolution and extraction of solute in the supercritical fluid. Using the relevant theory of supercritical fluid phase equilibrium, the gas-solid phase equilibrium thermodynamic model is established. Using the theory of thermodynamic phase equilibrium, the gas-liquid-solid phase equilibrium model is set up and verified by the experiment data. The sulfur deposition prediction model is established considering the Darcy and non-Darcy flow, and using it to study the porosity and permeability damage.Through the former research, the main conclusions are drawn from the following contents.