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| 盐效应和共同离子效应对方解石溶解度的影响及其地质意义 |
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陈勇1,2,王淼1,2,刘庆3,卓勤功4,张学军3,陈小兰5
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(1.中国石油大学地球科学与技术学院,山东青岛 266580;2.海洋国家实验室海洋矿产资源评价与探测技术功能实验室,山东青岛 266071;3.中国石油化工股份有限公司胜利油田分公司勘探开发研究院,山东东营 257015;4.中国石油勘探开发研究院,北京 100083;5.山东科技大学地球科学与工程学院,山东青岛 266590)
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| 摘要: |
| 储层矿物的生长和溶解受控于成岩流体,在恒定温度条件下,对不同盐度和离子类型溶液体系中的方解石溶解特性进行实验研究。结果表明,在低盐度(<20％)条件下,方解石溶解度随盐度增加而增大,但盐度过高会导致方解石溶解度降低,方解石溶解度最大值的盐度区间对应了高孔隙发育带;在相同浓度条件下,MgCl2体系中方解石的溶解度最大,NaCl体系中次之,KCl中最小,说明Mg2+的盐效应大于Na+和K+的盐效应,能促进方解石的溶解;Ca2+会因为共同离子效应而抑制方解石的溶解,反而有助于方解石沉淀(生长),其结果有助于地层保持良好的封闭性;Na2SO4的盐效应不明显,随浓度增大,方解石的溶解度快速降低;硫酸根对方解石溶解的抑制作用强于氯离子,表明Na2SO4水型可能不利于储层溶蚀次生孔隙的发育。 |
| 关键词: 方解石 溶解度 生长 盐效应 共同离子效应 储层物性 |
| DOI：10.3969/j.issn.1673-5005.2016.06.004 |
| 分类号::P 592 |
| 文献标识码:A |
| 基金项目:国家自然科学基金项目(41172111);国家科技重大专项(2016ZX05006-001);中央高校基本科研业务费专项(SD2013211151,6CX05005A) |
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| Effect of salts and common ions on solubility of calcite and its geological implications |
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CHEN Yong1,2, WANG Miao1,2, LIU Qing3, ZHUO Qingong4, ZHANG Xuejun3, CHEN Xiaolan5
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(1.School of Geosciences in China University of Petroleum, Qingdao 266580, China;2.Laboratory for Marine Mineral Resources, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China;3.Exploration and Development Research Institute of Shengli Oilfield Company, Dongying 257015, China;4.PetroChina Exploration and Development Institute, Beijing 100083, China;5.College of Earth Science and Engineering, Shandong University of Science and Technology, Qingdao 266590, China)
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| Abstract: |
| Growth and dissolution of minerals in petroleum reservoirs are controlled by the diagenesis fluids. The solubility characteristics of calcite in different salt and ions aqueous systems at stable temperature were investigated using experiments. The experimental results show that the solubility of calcite increases with the salinity rising (salinity<20％). However, it decreases under high salinity condition. And it is found that the fluids in reservoir contain salinity corresponding to the maximum solubility of calcite with high porosity. The solubility of calcite is the highest in MgCl2-H2O system, middle in NaCl-H2O system, lowest in KCl-H2O system at the same mole concentration of salt. This implies that the Mg2+ has stronger salt effect on solubility of calcite than Na+and K+, which improves the dissolution of calcite. The Ca2+ shows constraint on dissolving of calcite due to the common ion effect; however it may lead to growth of calcite, resulting in improving sealing ability of strata. The salt effect of Na2SO4 is not remarkable, and the solubility of calcite decreases quickly with Na2SO4 content increasing. The sulfate ion shows more constraint on dissolution of calcite than Cl-, which indicates that it is not suitable for forming of secondary porosity in reservoir containing Na2SO4. |
| Key words: calcite solubility growth salt effect common ion effect reservoir property |
