| 摘要: |
| 为了解有机酸溶蚀作用下泥页岩常见矿物离子的溶出规律,探讨溶蚀作用对泥页岩次生孔隙结构的影响,针对南堡凹陷古近系沙三段泥页岩样品设计了不同温度、不同类型有机酸(乙酸、乙二酸)环境下的溶蚀实验。对实验后反应溶液进行等离子发射光谱检测,溶蚀后样品进行X衍射、扫描电镜、低温氮气吸附等测试。结果表明:随反应温度升高泥页岩中常见矿物离子在乙酸、乙二酸中的溶出可分为“上升、下降、复合、甚微型”以及“上升、下降、复合型”两种情况,且常见离子的“溶出系数”各异,总体上有机酸对泥页岩溶蚀作用正温效应明显,不同类型有机酸溶蚀机制差异显著;溶蚀后泥页岩的粒内孔孔径增大、数量增多,粒间孔接触部分发生小规模溶蚀产生网洞化现象,微裂缝宽度有所增大,并伴随伊利石、高岭石、蒙脱石等新生黏土矿物生成;乙酸溶蚀促进泥页岩中孔、微孔的生成从而增大其比表面积,乙二酸溶蚀则提升中孔、大孔比例,进而提高泥页岩平均孔径;有机酸溶蚀对泥页岩增孔效应初步判别显示其增孔能力有限,并未达到预期效果。 |
| 关键词: 有机酸 溶蚀作用 离子释放 泥页岩孔隙结构 增孔效应 |
| DOI：10.3969/j.issn.1673-5005.2017.02.006 |
| 分类号::P 618.13 |
| 文献标识码:A |
| 基金项目:国家“973”计划项目(2014CB239005)；国家重大科技专项(2011ZX05001-001-006)；山东省自然科学基金项目(ZR2013DM016) |
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| Effect of mineral dissolution by organic acids on pore structure of shale reservoir |
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LUO Rui1, ZHA Ming1, HE Hao2, GAO Changhai1, QU Jiangxiu1, ZHANG Yong2, ZHU Wenhui2, SUN Chong2
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(1.School of Geosciences in China University of Petroleum,Qingdao 266580,China;2.Research Institute of Exploration and Development,Tarim Oilfield Company, PetroChina,Korle 841000,China)
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| Abstract: |
| In order to know the dissolution of common mineral ions in shale dissolved by organic acid, the impact of dissolution on secondary pore structure of shale was investigated, in which the dissolution experiments were designed on shale samples from the member 3 of Shahejie Formation of Paleogene in Nanpu sag with different types of organic acids (acetic acid and oxalic acid) and different temperatures. The plasma-atomic emission spectrometry was conducted on the solution after the reaction. Also, the X-ray diffraction, scanning electron microscopy and low-temperature nitrogen adsorption analysis were conducted on dissolved samples. The results show that dissolution of common mineral ions in shale with increasing reaction temperature has two situations, which are "increase, decrease, compound and little" by acetic acid, and “increase, decrease, compound” by oxalic acid respectively. And different ions show different dissolution coefficients. In general, the organic acid dissolution of shale shows obvious positive correlation with temperature. And different types of organic acids show different dissolution mechanisms on shale significantly. In the dissolved shale, the size and distribution of intragranular pore in shale increase. It is also found that the small scale of erosion occurs in the contact part of intergranular pore, resulting in net-pore phenomenon and increased width of micro crack. Also the accompanied new-born clay minerals are formed, such as illite, kaolinite and montmorillonite. The acetic dissolution promotes the formation of microporeand mesoporein the shale, which increases the surface area. Meanwhile oxalic acid dissolution results in the formation of mesopore and macropore, which increases the average pore size of the shale. The preliminary determination of shale porosity enhancement by organic acid dissolution shows the limited capacity of enhancing porosity, which is not as significant as expected. |
| Key words: organic acids dissolution ions release shale pore structure porosity enhancement effect |
