摘要
TSR(硫酸盐热化学还原反应)是高含硫化氢天然气形成的重要途径,是指烃类在高温条件下将硫酸盐还原生成H2S、CO2等酸性气体的过程。由于硫化氢的剧毒和强腐蚀性,在石油天然气行业的钻井、完井、修井、净化加工以及运输等各个方面的危害一直备受人们的关注,对硫化氢和TSR的评价一直是负面的,在油气勘探中更多是在回避。最近研究发现,TSR作用对石油天然气工业具有重要的积极作用。TSR的发生,首先需要硫酸盐类溶解提供SO42-,储集空间得到初步改善;其次TSR反应形成的硫化氢,溶于水后显示出较强的酸性溶蚀作用,对白云岩储层具有最佳的溶蚀效果。在高温条件和储层中地层水的作用下,硫化氢与白云岩发生较强烈的酸性流体-岩石相互作用(水岩反应),促进了白云岩次生孔洞的发育和高孔高渗优质储集层的形成,使油气储层保存下限增大和深部天然气聚集成藏成为可能。而目前飞仙关组高含硫化氢气藏普遍压力系数小、充满度低,这与TSR及硫化氢对储层溶蚀导致储集空间增容有关。四川盆地油气勘探结果证实,所有高含硫化氢天然气藏均对应了次生孔隙十分发育的优质储层,岩性主要以白云岩为主,储层埋藏深度超过8 000 m时依然发育优质储层。
Natural gas, with high contents of H2 S, is generated mainly by the important process of thermochemical sulfate reduction （TSR）. During this process, and under high temperature, hydrocarbons deoxidize sulfate to acidic gases, such as H2 S and CO2, Because of the viral and high corrosion dangers, more attention has been given to the harmful effects of H2 S in well drilling, completion, purifying processes, and in the transport in oil and gas industry. TSR and H2 S have been perceived as negative in the past and were shunned in the oil and gas exploration. Nevertheless, recent research shows that the TSR process plays an effective role in oil and gas industry. First, TSR process needs SO4^2- dissolved from sulfate, which causes the reservoir pore space to make an initial elementary improvement; secondly, the H2S generated by TSR processes is dissolved in water and exhibit strong acidity, which results in the corrosion of dolostone. Under high temperature conditions and with water involved in the process, H2 S and dolostone give rise to a strong interaction between acidic fluid and rock （water/rock reaction）. This stimulates the development of secondary pores and the formation of highquality reservoir with high porosity and permeability. The corrosion increases the lower conservation limit of oil and gas reservoir and makes the formation of a deep natural gas reservoir possible. Nowadays, the Feixianguan formation （T1 f fm. ） shows lower pressure coefficient and filling degree, which is related to the reservoir＇s dilation caused by the corrosion in the TSR process. The exploration results have proved that all the natural gas with high contents of H2 S were found in high-quality reservoirs, with sufficiently developed secondary pores, in Sichuan basin, southwest China, where the lithology is mainly dolostone. High-quality reservoirs may still be present to depths of more than 8 000 m.
出处
《地学前缘》
EI
CAS
CSCD
北大核心
2006年第3期141-149,共9页
Earth Science Frontiers
基金
中国石油天然气股份公司科技项目(中国高含硫化氢天然气田资源分布与开发战略:040502-10-01)
国家重点基础研究发展规划资助项目(2001CB209100)
