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本文系统剖析了鄂尔多斯中部气田下古生界水化学特征及与天然气藏的关系 ,初步提出了天然气藏富集区 (或含气区 )的水化学综合判识指标。鄂尔多斯中部气田下古生界地层水以偏酸性为主 ,具有总矿化度高、Cl-和Ca2 + 离子占优势、有机酸和烷基酚含量高的特征 ,反映出下古生界地层水处于阻滞—停滞的水文地质状态 ,有利于天然气的聚集与保存。研究认为 ,水化学组成与天然气藏有密切的关系 ,总矿化度高值区 (>15 0 g/l)、CaCl2型水分布区、rNa/rCl低值区 (≤ 0 3)、rCl/rMg高值区 (>15 )、rMg/rCa低值区 (≤ 0 2 )、有机酸含量高值区 (>40mg/l)和酚含量高值区 (>2 0mg/l) ,将是天然气藏富集的有利区。因此 ,利用水化学和地质地球化学相结合的综合研究 ,可为天然气藏富集区 (或含气区 )的找寻和预测提供依据。
This paper systematically analyzes the lower Paleozoic hydrate characteristics and the relationship with the natural gas reservoirs in the central Ordos gas field, and initially puts forward the water chemistry comprehensive identification index of the natural gas reservoir enrichment area (or gas-bearing area). The lower Paleozoic formation water in the central Ordos gas field is mainly acidic in nature. It has the characteristics of high total salinity, Cl- and Ca2 + ions and high content of organic acids and alkylphenols, reflecting that the Lower Paleozoic formation water In a stagnant, stagnant hydrogeological state, it is good for the accumulation and preservation of natural gas. The study shows that the chemical compositions of water are closely related to natural gas reservoirs. The areas with high total salinity (> 150 g / l), water with CaCl2 type, low rNa / rCl (≤ 0 3), rCl / High rMg values (> 15), rMg / rCa low values (≤ 0 2), high organic acid values (> 40 mg / l) and high phenol content (> 20 mg / l) Tibet rich set of favorable areas. Therefore, the integrated study of water chemistry and geo-geochemistry can provide the basis for the search and prediction of enrichment areas (or gas-bearing areas) in natural gas reservoirs.