摘要
鄂尔多斯盆地二叠系石盒子组盒8段致密砂岩储层发生过强烈溶蚀改造,形成了广泛的次生孔隙。但是地质条件下砂岩内长石矿物、方解石胶结物的溶蚀过程及储层效应还有待深入研究。采用封闭体系下的温压共控岩溶模拟方法,结合电感耦合等离子体发射光谱仪、X?射线衍射仪、偏光显微镜和扫描电镜等测试分析,对盒8段致密储层砂岩开展不同温压条件下,含钙岩屑砂岩和长石质岩屑砂岩在乙酸溶液中溶蚀规律研究。实验结果显示:温度升高使长石溶蚀速度增快、溶蚀量增加,但是Al3+迁移量先增大再减小,所以深层砂岩中Al3+很难被迁移出来;方解石溶蚀速率远快于长石,对储层次生孔隙贡献更大;温度升高方解石溶蚀量先增大再减小,压力会抑制方解石溶蚀并且比温度的影响更大。盒8段砂岩三叠纪晚期至白垩纪早期方解石和长石发生了溶蚀作用,这是次生孔隙生成的主要时期,随后砂岩继续深埋时,温度压力升高使方解石发生沉淀;白垩纪中期以后储层抬升使温度、压力不断降低,部分方解石会发生溶蚀。
The tight sandstone reservoir in 8th member of the Permian Shihezi Formation in the Ordos Basin has undergone intense dissolution and transformation,forming a wide range of secondary pores.However,the dissolution process and reservoir effect of feldspar minerals and calcite cement in sandstone under geological conditions have yet to be further studied.In this paper,the method that temperature and pressure co-controlled the dissolution simulation experiment under closed system was adopted,and the dissolution law of calcium-bearing litharenite and feldspathic litharenite in acetic acid solution was studied under different temperature and pressure conditions by means of test and analysis of inductively coupled plasma emission spectrometer,X-ray diffractometer,polarizing light microscope and scanning electron microscope.The experimental results show that the temperature increases the dissolution rate and the dissolution amount of feldspar,but the amount of Al3+migration first increases and then decreases,so it is difficult for Al3+to be migrated out of the deep sandstone.Calcite dissolves much faster than feldspar and contributes more to the pore formation.As the temperature increases,the calcite dissolution first increases and then decreases,and the pressure inhibits calcite dissolution and has a greater effect than temperature.Calcite and feldspar of He 8 Member dissolved in the Late Triassic to the early cretaceous,which was the main period of secondary pore formation.After the Middle Cretaceous,the reservoir uplifted and the temperature and pressure decreased continuously,and caused some calcite to dissolve away.
作者
郭壘
李程善
范立勇
康锐
张英
陆应新
张明峰
吕成福
GUO Lei;LI Cheng-shan;FAN Li-yong;KANG Rui;ZHANG Ying;LU Ying-xing;ZHANG Ming-feng;Lü Cheng-fu(Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Lanzhou 730000,China;University of Chinese Academy of Sciences,Beijing 100049,China;Department of Exploration,PetroChina Changqing Oilfield Company,Xi’an 710018,China;Exploration&Development Research Institute,PetroChina Changqing Oilfield Company,Xi’an 710018,China)
出处
《天然气地球科学》
EI
CAS
CSCD
北大核心
2020年第9期1250-1260,共11页
Natural Gas Geoscience
基金
国家自然科学基金(编号:41972155)资助。
关键词
乙酸
方解石
长石
水岩反应
石盒子组
Acetic acid
Calcite
Feldspar
Water-rock reaction
Shihezi Formation
