咸化湖盆碎屑岩储层中铁白云石的溶蚀作用模拟实验研究

Simulation experiment for ankerite dissolution in clastic reservoir of saline lacustrine basin

黄成刚 袁剑英 曹正林 张世铭 王莹 佘敏 米海杰

Huang Chenggang Yuan Jianying Cao Zhenglin Zhang Shiming Wang Ying She Min Mi Haijie

中国石油勘探开发研究院西北分院 油藏描述重点实验室, 兰州 730020 2. 中国石油杭州地质研究院 碳酸盐岩储层重点实验室, 杭州 310023 3. 甘肃省地质矿产勘查开发局 第二地质矿产勘查院, 兰州 730020

Key Laboratory of Reservoir Description (NWGI), Research Institute of Petroleum Exploration and Development-Northwest, PetroChina, Lanzhou, Gansu 730020, China 2. Key Lab of Carbonate Reservoir, Hangzhou Research Institute of Geology, PetroChina, Hangzhou, Zhejiang 310023, China 3. No.2 Geology and Mineral Exploration Institute, Bureau of Geology and Mineral Exploration and Development of Gansu Province, Lanzhou, Gansu 730020, China

一般研究认为岩石中的碳酸盐矿物在酸性条件下易发生溶蚀作用从而生成次生孔隙，进而增大岩石的储集空间和渗透性。柴达木盆地砂西地区始新统下干柴沟组碎屑岩储层为咸化湖盆沉积，偏光显微镜下和扫描电镜下可见石膏和铁白云石较为发育。通过流体—岩石动力学模拟实验研究得出，在地层条件下高温高压环境中铁白云石易发生溶蚀作用从而形成次生孔隙，石膏在其中起催化作用；铁白云石溶蚀生成的铁、镁离子为高岭石转化为绿泥石提供了必要的物质条件，生成的针叶状绿泥石极易堵塞较细的孔隙喉道造成了岩石渗透率的下降，但铁白云石等易溶矿物的溶蚀作用增加了岩石的孔隙度。

It is generally believed that carbonate minerals can easily dissolve. This process will lead to the formation of secondary pores, thereby enlarging the reservoir space and improving the permeability of reservoir rocks. In the Qaidam Basin, clastic reservoirs of the Lower Eocene Gancaigou Formation are deposits of saline lacustrine basin, with plaster and ankerite well developed in rock flacks as revealed by polarized light microscopy and scanning electron microscope. Experimental results of fluid-rock dynamic stimulation show that the ankerite dissolution can generate secondary pores, and gypsum catalyzes the dissolution. The iron and magnesium ions generated are reactants in the transformation from koalinite to chlorite. The foliated chlorite easily blocks thin throat, leading to the decrease of permeability, while the dissolution of easily soluble minerals like ankerite increases porosity.

中国石油重大科技专项“柴达木盆地建设千万吨油气田综合配套技术研究”(2011E-03)、国家油气专项“前陆盆地油气成藏规律、关键技术及目标评价”项目(2011ZX05003)和中国石油天然气股份有限公司勘探开发研究院青年创新基金联合资助。

https://doi.org/10.11781/sysydz201405650