致密砂岩油藏水驱油效率及微观影响因素研究—以鄂尔多斯盆地华庆地区三叠系长6储层为例
任大忠，刘登科，周兆华，周 然，柳 娜，孙 卫致密砂岩油藏水驱油效率及微观影响因素研究—以鄂尔多斯盆地华庆地区三叠系长6储层为例
任大忠1，2，刘登科2，周兆华3，周 然4，柳 娜5，孙 卫2
（1.西安石油大学石油工程学院，陕西 西安 710065；2.西北大学大陆动力学国家重点实验室，陕西 西安 710069；3.中国石油勘探开发研究院廊坊分院，河北 廊坊 065007；4.中国石油川庆钻探工程有限公司钻采工程技术研究院，陕西 西安 710021；5.中国石油长庆油田分公司勘探开发研究院，陕西 西安 710018）
摘 要 以鄂尔多斯盆地华庆地区延长组长6段致密砂岩油藏为例，在岩石学特征、物性和孔隙结构等方面表征研究区致密砂岩储层非均质性的基础上，开展真实砂岩微观驱替实验及非稳态恒压法水驱油实验，分析了不同类型储层油水分布规律及渗流特征，系统评价了致密砂岩储层驱油效率及微观影响因素。结果表明：长6段致密砂岩不同类型储层驱油效率具有显著差异。孔隙度和渗透率越大驱油效率越高，孔隙度＜10%，渗透率＜0.2×10-3 μm2的储层驱油效率受物性控制明显；喉道半径、孔隙半径的增大及孔喉连通性变好导致相对较高的驱油效率，平均喉道半径＞0.7 μm，主流喉道半径＞1.0 μm，孔隙喉道比＞400时驱油效率变化趋势变缓，主流喉道半径是影响无水期驱油效率的主导因素，随着渗流路径增多增宽，孔隙半径对最终期驱油效率的控制作用不容忽视；伊利石、伊/蒙混层、碳酸盐及泥质含量越高，驱油效率越低，颗粒点接触保障了较高的驱油效率；可动流体饱和度与驱油效率呈正相关关系，中性-亲水性储层驱油效率较高。
关键词 华庆地区; 致密砂岩油藏; 水驱油效率；微观影响因素
中图分类号：TE12；TG115.21+3；TG115.21+5.3 文献标识码：A doi:10.3969/j.issn.1000-6281.2019.04.008
Research on waterflooding efficiency of tight sandstone reservoir and its microscopic influence factors: taking the triassic chang 6 member in Huaqing area, Ordos basin，NW China as an example
REN Da-zhong1，2，LIU Deng-ke2，ZHOU Zhao-hua3，Zhou Ran4，LIU Na5，SUN Wei2
(1.College of Petroleum Engineering ,Xi’an Shiyou University , Xi’an Shaanxi 710065；2.State Key Laboratory of Continental Dynamics，Northwest University，Xi’an Shaanxi 710069; 3.Langfang Branch of PetroChina Research Institute of Petroleum Exploration and Development ,Langfang Heibei 065007; 4. Drilling and Production Technology Research Institute，CNPC Chuanqing Drilling Engineering Company Limited，Xi’an Shaanxi 710021; 5.Research Institute of Petroleum Exploration and Development , PetroChina Changqing Oilfield Company, Xi’an Shaanxi 710018,China)
Abstract Taking the Triassic Yanchang formation tight sandstone reservoirs in Ordos basin，NW China as an example, and based on the analysis of lithological characteristics, physical properties, pore structure characterizing the non-homogeneity of reservoir, waterflooding seepage experiment with real sandstone micromodel and with unsteady state constant pressure were carried out to analyses the differences of the characteristics of oil and water distribution and seepage, synthetically evaluate reservoir waterflooding efficiency of tight sandstone as well as its microscopic influence factors. The results show that waterflooding efficiency of tight sandstone reservoirs have significant variation in research area. Physical properties have positive correlations with waterflooding efficiency, and have obvious control on the reservoirs with porosity under 10% and permeability under 0.2×10-3 μm2. Waterflooding efficiency has positive correlations with throat and pore radius, and good pore-throat connectivity assured high waterflooding efficiency. Generally, the increasing and decreasing trend of oil displacement efficiency will be obviously weakened in the cases of the average throat radius greater than 0.7 μm, the mainstream throat radius greater than 1.0 μmand the pore-throat radio greater than 400. Mainstream throat radius dominates the no water waterflooding efficiency, pore radius has some influence on ultimate waterflooding efficiency with the wider and increased percolation path. Waterflooding efficiency has negative correlations with illite, mixed-layerminerals of illite and smectite, carbonate minerals and shale mass fraction. Point contact guaranteed high level of waterflooding efficiency. High movable fluid saturation, neutral and hydrophilic reservoirs lead to high waterflooding efficiency.
Keywords Huaqing area；tight sandstone reservoir；waterflooding efficiency；microscopic influence factors
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