高含硫气藏中元素硫沉积形态和微观分布研究

THE DEPOSITION PATTERN AND MICRODISTRIBUTION STUDY ON ELEMENTAL SULFUR IN THE HIGH SULFUR CONTENT GAS RESERVOIRS

元素硫沉积是高含硫气藏开采过程中存在而又必须解决的难题之一。随着高含硫气藏储层压力不断下降,元素硫溶解度也不断下降,一旦元素硫溶解度低于元素硫含量,元素硫就会从地层中沉积下来。沉积的元素硫会堵塞地层孔隙,降低渗透率,严重影响气井产能。为了研究元素硫在地层中的沉积形态和沉积特征,利用自主设计的实验流程和实验方法,使TD5-1井高含硫气体通过岩芯,并降低压力让元素硫在岩芯中沉积下来,然后对沉积了元素硫的岩芯进行电镜扫描和能谱分析,首次得到了元素硫在岩芯中的沉积形态,即元素硫主要以膜状形式分布在岩芯孔隙壁面上。该研究结果为深入认识、掌握元素硫沉积规律以及指导高含硫气藏合理开发奠定了基础。

The study on the sulfur deposition belongs to one of four important tasks to develop the high sulfur gas reservoirs safely and reasonably.With the decrease of the formation pressure in the high sulfur gas reservoirs,the solubility of elemental sulfur is descending.Once the solubility of elemental sulfur is less than the elemental sulfur content,the elemental sulfur will deposit from the formation.The deposited sulfur blocks the formation pore space and reduces permeability,which severely impacts the gas deliverability.In order to study the deposition pattern and feature of the sulfur,the experiment is carried out by using the TD5-1 gas passing the core to deposit the elemental sulfur in lower pressure,then,the core is analyzed by Scanning Electron Microscope (SEM) and energy spectrum.The deposition pattern and micro-distribution on elemental sulfur is drawn,i.e.,the elemental sulfur distributes around the pore surface filmily.The results can lay foundation for further understanding and guiding the reasonable development of the high sulfur content gas reservoirs.