导　　师： 张足斌

学科专业： 082003

授予学位： 硕士

作　　者： ;

机构地区： 中国石油大学华东

摘　　要： 硫沉积研究是高含硫气田开发技术中的一项重要课题，研究的焦点多集中在气藏地层和井筒中，集输系统中硫沉积问题近年来逐渐引起重视。地面集输系统中沉积的元素硫不仅会带来严重的腐蚀问题，而且会引起管道和设备的堵塞，严重时甚至造成气田的停产。因此，准确地描述和分析地面管线和设备中硫沉积的机理及影响因素，掌握元素硫的沉积规律，开发科学有效的防控技术，是当今国内外高含硫天然气开发领域研究的难点之一。 本文通过现场试验和统计方法，确定了地面管道和设备内元素硫沉积物的种类为斜方硫，并观察到管道内元素硫的动态沉积过程。建立了元素硫的溶解度模型，理论分析了地面集输系统中元素硫的沉积机理和影响因素，通过数值模拟研究了流场对元素硫沉积的影响，提出了有效的防控技术。 研究结果表明，集输系统管道和设备内元素硫沉积的机理主要为成核和分子扩散。对现场新发现的管道内环壁等厚度硫沉积现象做出了解释：析出的硫微粒在气流脉动和布朗运行的协同作用下，一方面与管壁碰撞后均匀粘附在管壁上；另一方面，未与管壁发生碰撞的悬浮硫微粒，在管截面温度梯度和速度梯度的耦合作用下，向管壁处扩散迁移；沉积在管壁上的元素硫具有剪切稀释性，在气流作用下导致管壁元素硫等厚度沉积现象。基于热力学气固相平衡原理，提出了元素硫溶解度计算模型，建立了元素硫成核和聚团增长的理论模型。 硫沉积模拟结果表明：闸板阀后流场存在“死区”，“死区”一方面加速元素硫的析出，另一方面减弱了气流对沉积物的携带作用；蝶阀后流场存在剧烈扰动，增加了硫微粒碰撞管壁的几率；汇管入口支管附近壁面剪切应力较大，中间部位易发生硫沉积。 提出了集输系统硫沉积的井口防治方案，分析硫沉积和水合物形成之间的关系：天然气中硫化氢含量越高，越易形成水合物；析出的元素硫作为水合物的结晶中心，促进了水合物的形成。 The sulfur deposition has always been an important and difficult problem in thedevelopment process of gas reservoirs with high H2S content. Most past researches focusedon gas reservoirs and bore holes, the elemental sulfur deposition problem in the natural gasgathering system has been emphasized by scholars only in recent years. In the developmentand processing of gas field, this deposition can cause serious corrosion and block in pipelinesand other facilities. As a result, accurate description and analysis of the mechanism andinfluential factors of sulfur deposition, deep unstanding of the law of elemental sulfurdeposition and the development of scientific and efficient prevention and control technologyhas become one of today’s key issues and difficulties in domestic and foreign exploration ofhigh sulfur content natural gas. This research project has been able to identify the type and mechanisms associated withthe formation and deposition of ‘elemental sulfur’ in natural gas gathering pipelines andassociated equipment. A model is developed to predict the solubility of elemental sulfur inhigh sulfur content natural gas and numerical simulation on the flow field in the pipeline hasbeen carried out using the commercial computational shareware-Fluent. The new technologieswill be applied in the wellhead to prevent and control the sulfur deposition. There are two kinds of sulfur deposition mechanisms: nucleation and moleculardiffusion. Based on a new discovery of the equivalent thickness sulfur deposition layer in theinternal wall of the pipeline, the mechanism of formation is also presented: one part of sulfurparticles adhere to the internal wall surface in the presence of gas pulsation and Brownianmotion; the other part of sulfur particles migrate to the internal wall surface in the presence oftemperature gradient and velocity gradient; the deposition has the property of shear-thinning behavior, so the deposition becomes the equivalent thickness with the action of gas flow.Based on the principle that gas and solid fugacity are identical in both phases, the model topredict the solubility of elemental sulfur in high sulfur content natural gas is developed. Therough surface can promote the deposition of sulfur. The ‘dead zone’ is located immediately downstream of gate valve. The ‘dead zone’accelerates the deposition rate of sulfur particles, and at the same time, it decreases thecarrying rate of gas flow. The turbulence of the flow field located downstream of the butterflyvalve increases the probability of collision of particles with a wall. The deposits of elementalsulfur are most commonly found at the middle of manifold. Relationship between the hydrate formation conditions and sulfur deposition is analyzed.Gas hydrate forms more easily with a higher H2S content. The sulfur particles can promotethe formation of hydrates by being the nucleuses.

关 键 词： 高含硫天然气 硫沉积机理 溶解度 流场 防控技术

分 类 号： [TE977]

领　　域： [石油与天然气工程]