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通过对本溪组地层水性质与地球化学特征的详细研究表明:研究区地层水呈弱酸性,总矿化度介于50.68~391.74 g/L,阴、阳离子分别以Cl~-,Ca~(2+),K~++Na~+含量占优势为特征,水型为单一CaCl_2型;钠氯系数(rNa/rCl)介于0.18~0.49,平均为0.35;脱硫酸系数(100×rSO_4/rCl)在0~0.53,平均为0.1,指示其经历了强烈的浓缩变质与脱硫酸作用的改造。研究后认为,纵向上,随着深度的增加,地层水各特征参数的化学剖面在宏观上呈现出3种变化类型:先增后减型、增减交替型、波状递增型;整体上TDS(本2)rNa/rCl(本1),rSO_4×100/rCl(本2)>rSO_4×100/rCl(本1),这表明在流体(气、水)运移过程中,作为优势通道的不整合面使得与其相邻的本2段较本1段具有更强的开放性和流动性,且储层砂岩次生孔隙更为发育{rCa/rMg(本2)>rCa/rMg(本1)}。平面上天,然气在整体自西南向北、东向运移的路径上,其组分中CH_4含量逐渐增高,而N_2含量逐渐降低,呈现出较强的水溶气运聚特征。在运移过程中,天然气遇到合适的圈闭,则逐渐聚集起来形成气藏,且地层趋于封闭的还原环境,有利于天然气的保存。
Through the detailed study on the properties and geochemical characteristics of the formation water in Benxi Formation, it shows that the formation water in the study area is weakly acidic with the total salinity ranging from 50.68 to 391.74 g / L, and the positive and negative ions are Cl ~ -, Ca ~ (2) (Superscript +) and K ~ + + Na ~ +, and the water type was single CaCl2 type. The sodium chloride coefficient (rNa / rCl) ranged from 0.18 to 0.49 with an average of 0.35. ) At 0 ~ 0.53, an average of 0.1, indicating that it has undergone a strong concentration of metamorphic and desulfurization acid transformation. According to the study, in the vertical direction, with the increase of depth, the chemical profile of each characteristic parameter of formation water shows three types of changes macroscopically: increase first and then decrease, increase and decrease alternation and waviness; on the whole TDS ( RNa / rCl (present 1), rSO_4 × 100 / rCl (present 2)> rSO_4 × 100 / rCl (present 1), indicating that in the fluid (Gas and water), the unconformity as the dominant channel makes the adjacent 2 sections more open and fluid than the first one and the secondary porosity of reservoir sandstone is more developed { rCa / rMg (this 2)> rCa / rMg (this 1)}. On the plane of heaven, the content of CH_4 gradually increased and the content of N_2 gradually decreased in the whole path of gas migration from southwest to north and east, showing a strong feature of migration and accumulation of water-soluble gas. During the migration process, natural gas encounters suitable traps, then gradually accumulates to form gas reservoirs, and the strata tend to be closed and restored to the environment, which is good for the preservation of natural gas.