硫沉积对裂缝导流能力影响的实验研究

An Experimental Study on Fracture Conductivity Influenced by Sulfur Deposition

含硫气藏在生产过程中会出现单质硫的沉积,引起较大危害,而压裂技术作为气藏增产的主要措施,常由于受高含硫气藏开发中的硫沉积堵塞等原因导致酸蚀裂缝导流能力大幅降低而逐渐失去作用,为了能较好的反映硫沉积对裂缝导流能力的影响以及评价酸化措施对硫沉积后裂缝导流能力的改善效果,采用硫粉和人工造缝后的岩心,模拟硫颗粒沉积对酸蚀裂缝的堵塞,在此基础上酸蚀裂缝,测试裂缝的气测裂缝导流能力.研究表明,硫颗粒堵塞裂缝,导致裂缝导流能力严重降低,以15 MPa为例,裂缝导流能力降低17％～47％,而注入酸液能侵蚀岩石壁面,导流能力降低系数从2.79 ～ 3.23恢复到1.0左右,在一定程度上恢复裂缝的导流能力.

Deposition of solid elemental sulfur may arouse severe damage to the formation and significantly affect the gas deliverability in sour gas reservoirs.As one main measure of stimulation,hydraulic fracturing always ceases to work due to the sulfur deposition in the fractures.To have a better understanding of the failure of fracture conductivity caused by sulfur deposition and learn the degree of fracture conductivity improved by aciding,an experimental was implemented and studied.both the sulfur powder and an artificial fractured core was employed to simulate the process of sulfur deposition in the fractures.A further step was made to inject some hydrochloric acid into the blocked fracture caused by sulfur powder.The results show that the fracture conductivity can be greatly reduced by the sulfur deposition.The fracture conductivity can be decreased by 17％ ～47％ due to sulfur deposition.However,to some degree,aciding fracturing can improve the conductivity of fracture by eroding the surface of fracture.This means the failure of fracture blocked by sulfur deposition can be improved by aciding.