| 摘要: |
| 在统计分析东营凹陷沙河街组主要预探井和评价井地层水和岩心物性资料的基础上,考察沙四段地层水化学性质及其指示意义,分析其与储层物性演化之间的关系。结果表明:沙四段地层水以氯化钙型为主,整体封闭程度好,处于还原的水体环境,总体矿化度高且具有垂向递增性和侧向不均一性;pH值是影响储层物性的主要因素,pH越小地层水矿化度越大,酸性地层水对储集物性的改善贡献相对较大;沙四段地层水仍以弱酸性为主,但地层中石英和碳酸盐矿物含量的变化、地层水中HCO3-含量的变化和黏土矿物之间的相互转化表明沙四段整体上处于酸性向碱性过渡的时期并以碱性成岩环境为主;沙四段地层储集物性较上覆地层有所降低,且随着埋深的增加,碱性成岩环境越占优势,储集物性变差;横向上北部陡坡带地层储集物性要好于中央隆起带和南部缓坡带;地层水矿化度可以作为判断相似地层储集物性发展趋势的重要指标,即地层水矿化度升高说明溶蚀作用强度大于胶结作用,储集物性变好;碳酸盐矿物的沉淀或溶解是影响沙四段储层孔隙度的主控因素(相关系数R≈0.81),沙四段碳酸盐矿物更趋向于沉淀析出形成胶结物,而溶蚀作用强度远小于上覆地层,储集物性相对较差。 |
| 关键词: 东营凹陷 沙四段 地层水地球化学特征 储层物性 成岩环境 矿化度 |
| DOI：10.3969/j.issn.1673-5005.2015.04.006 |
| 分类号::P 592 |
| 基金项目:国家自然科学基金项目(41172111);山东省优秀中青年科学家奖励基金项目(BS2012NJ014);中央高校基本科研业务费专项(SD2013211151) |
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| Chemical characteristics and implications of formation water of the Es4 Member in Dongying sag |
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CHEN Yong, WANG Miao, WANG Xintao, WANG Chengjun, HAN Yun
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(School of Geosciences in China University of petroleum, Qingdao 266580, China)
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| Abstract: |
| On the basis of statistical analysis of the formation water and core physical properties in preliminary prospecting wells of the Es4 Member in Dongying sag, the chemical properties of formation water and its indication were investigated. And the relationship between the chemical properties of formation water and the evolution of the reservoir physical properties was analyzed as well. The results show that the formation water type of the Es4 is mainly CaCl2, which indicates that the reservoirs are good closure and reductive environment. The total salinity of formation water is high, which increases steadily in vertical and is uneven in lateral. The pH value of the formation water is the main factor of affecting the physical properties of reservoirs. Low pH corresponds to the high salinity, and the acidic formation water has great contribution to the improvement of reservoir physical properties relatively. Although the formation water of the Es4 is dominated by acid, the variation of the quartz and carbonate minerals content, the variation of the HCO-3 content in the formation water and the transformation of clay minerals indicate the Es4 is in the stage of transition from acid to alkaline on the whole. The diagenetic environment is dominated by the alkaline, and the reservoir physical properties of the Es4 are deteriorated compared to the overlying strata. With the increasing depth of burial the physical properties will be worse. The reservoir physical properties of the north steep slope belt are better than those of the central rise belt and the south gentle slope belt in lateral. The salinity of formation water can be used as an important indicator to determine the trend of physical properties of the reservoirs, that is to say, the increase of the salinity indicates that the dissolution strength is greater than the cementation strength and the physical properties of reservoirs will be better. It is also found that the dissolution and precipitation of the carbonate minerals is the dominated factor in terms of the porosity (R≈0.81), and the carbonate minerals of the Es4 tend to precipitate while the dissolution is far less than the overlying strata, resulting in the relatively deteriorated physical properties of the reservoir. |
| Key words: Dongying sag the Es4 Member chemical properties of formation water physical properties of reservoirs diagenetic environment salinity |
