摘要
根据川东北地区飞仙关组气藏中油田水的分析测试资料及实际地质情况,探讨该区高含H2S气藏中油田水的成因及地球化学特征、影响油田水化学性质的因素及与油气聚集、保存的关系。研究结果表明:川东北地区飞仙关组油田水是以阴、阳离子分别为Cl-和(Na++K+)为主的Na2SO4型水,只有少数是CaCl2型和NaHCO3型;地层水度矿化度分布范围较宽主要与碳酸盐岩储层具有较强的非均质性有关,导致TSR反应过程中产生的淡水与原生油田水混合不均匀,同时TSR作用过程中产生的淡水会降低原始油田水矿化度。研究区高含H2S地层和高含SO42-油田水分布特征基本相似,高值区主要分布在海槽东侧蒸发台地相,而海槽相及海槽西侧开阔台地相SO42-含量低,油田水中SO42-质量浓度分布控制了气藏中H2S和溶解H2S质量浓度的分布。高含H2S气藏油田水中阳离子质量浓度基本比低含H2S气藏的小,阴离子中Cl-含量也明显较其他低含H2S气藏油田水的低,而SO42-含量远远比低含H2S气藏的高。该区油田水水型、钠氯系数、脱硫系数出现异常及阴离子中Cl-含量明显偏低都主要与储层中膏质盐类的溶蚀导致油田水中SO42-质量浓度增高密切相关,因此,研究区这种高矿化度的Na2SO4型油田水并不代表地层对油气的保存不利,相反为该区天然气的有利富集区。研究区高含H2S气藏和低含H2S气藏油田水最主要差别在于SO42-含量,微观上典型气藏产气层和产水层油田水中SO42-和溶解H2S之间存在此消彼长的关系与TSR反应有关,气-水界面及附近水层中更有利于TSR反应的发生。
Based on the geochemical analysis of oilfield water from gas reservoir with high-content of H2S and local geological characteristics of Feixianguan formation, the origin, geochemical characters of oilfield water and factors influencing the attributes of oilfield water and gas accumulation were analyzed. The results show that the main chemical composition is dominated by Cl^- and（Na^＋＋K^＋）, which can be classified as Na2SO4 type water, and only a few samples belongs to CaCl2 type and NaHCO3 type water. The wide distribution of oilfield water salinity are mainly related with significant heterogeneity of carbonate reservoirs, which leads the primary oilfield water to be mixed by fresh water derived from TSR and its salinity can be decreased. The distributional characteristic of high content of H2S reservoir is consistent with the distribution of oilfield water with high content of SO4^2-. The high value areas are mainly located in the east side of trough with evaporate platform facies, while trough facies and open-platform facies in the west side of trough are characterized by low level of SO4^2-. Besides, the distribution of SO4^2- controls the distribution of free H2S and dissolved H2S in gas reservoir. The content of cation and Cl^- from oilfield water with high level of H2S is lower than the counterparts from gas reservoir with lower level of H2S. But the situation of SO4^2- is intensely opposite. The geochemical analysis about oilfield water shows that the types of water, sodium to chloride coefficient and desulfurization coefficient are abnormally affected by the gypsum rocks dissolution that arouses the high content of SO4^2-, and therefore, it can not be concluded that the formation, with high content of H2S in oilfield water, in study area is against gas accumulating, on the contrary, there may be the favorable zone. The significant difference between low H2S area and high H2S area is the content of SO4^2-, the reciprocal relationship between SO4^2- and dissolved H2S in oilfield waters of typical gas reservoir production gas and water yield formation are related with TSR reaction. The TSR are more likely to occur in gas-water interface and the nearby water zone.
出处
《中南大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2014年第10期3477-3488,共12页
Journal of Central South University:Science and Technology
基金
国家自然科学基金资助项目(40773039)
国家重点基础研究发展计划("973"计划)项目(2011CB201102)~~
关键词
硫化氢
气藏
油田水
地球化学特征
飞仙关组
川东北
hydrogen sulphide
gas reservoir
oilfield waters
geochemical characteristics
Feixianguan formation
Northeastern Sichuan Basin
