摘要
准噶尔盆地西北缘中拐凸起佳木河组致密砂岩储集层岩心实测渗透率主要分布在0.100~1000.000 mD,与测井渗透率相差4~6个数量级,实测渗透率明显失真,影响了储集层评价的准确性。从研究区地质背景出发,综合测井和岩心资料,通过对该区10口井644块样品薄片进行分析,结合压汞法、铸体薄片、X射线衍射、图像分析统计等,分析了储集层物性实测值失真主因。研究结果表明:取至地表的岩心中,胶结物浊沸石减压膨胀形成的假粒缘缝,是引起测试岩心渗透率异常偏高的主因;浊沸石含量与假缝面孔率、地层电阻率与中子孔隙度比值呈正相关;当浊沸石含量小于5%,假缝面孔率在1%以下,孔隙度与渗透率呈良好相关关系,但随着浊沸石含量增加,渗透率明显变大(多数在1.000 mD以上),与区内储集层类型和测井结果不符。通过分析岩石薄片和测井资料,确定假缝面孔率与浊沸石含量和假缝孔隙度的关系,并参照测井孔隙度,剔除假缝孔隙度,得到校正后的真孔隙度和对应的渗透率。校正后的储集层渗透率主要分布在0.001~5.000 mD,与测井渗透率接近,证实校正方法可靠。
The measured permeability of the cores from the tight sandstone reservoir in the Jiamuhe formation of the Zhongguai uplift in the northwestern margin of the Junggar basin ranges from 0.1 mD to 1000 mD,which is 4-6 orders of magnitude different from the permeability calculated from logging.The measured permeability is obviously distorted,which affects the accuracy of reservoir evaluation.Based on the geological background of the study area and combined with well logging and core data,644 thin sections from 10 wells in the area are ana⁃lyzed and the main causes of reservoir physical property distortion are studied based on mercury injection method,cast thin section,X⁃ray diffraction,image analysis and statistics and other methods.The results show that the pseudo granular marginal fractures formed by the de⁃compressed expansion of the cement laumontite are the main reason for the abnormally high permeability measured from the cores taken to surface;the content of laumontite positively correlates to the surface porosity of pseudo fracture,and to the ratio of formation resistivity to neutron porosity.When the laumontite content is less than 5%,and the surface porosity of pseudo granular marginal fractures is less than 1%,the porosity has a good correlation with permeability.However,with the increase of the laumontite content,the permeability increases obviously(mostly more than 1 mD),which is inconsistent with the reservoir type and well logging results in the area.Based on the analysis of rock thin section and well logging data,the correlations between surface porosity of the pseudo fractures and laumontite content and pseu⁃do fracture porosity are determined.By referring to the well logging porosity and eliminating the pseudo fracture porosity,the corrected true porosity and corresponding permeability values are obtained.The corrected reservoir permeability values mainly range from 0.001 mD to 5.000 mD,which is close to the permeability from well logging interpretation,proving that this correction method is reliable.
作者
杨川
吴涛
李啸
曾德龙
仇鹏
冯鑫
戴灿鑫
YANG Chuan;WU Tao;LI Xiao;ZENG Delong;QIU Peng;FENG Xin;DAI Canxin(Research Institute of Exploration and Development,Xinjiang Oilfield Company,PetroChina,Karamay 834000,China)
出处
《新疆石油地质》
CAS
CSCD
北大核心
2021年第6期749-755,共7页
Xinjiang Petroleum Geology
基金
国家科技重大专项(2017ZX05001)
中国石油科技重大专项(2017E-0410)。
关键词
准噶尔盆地
中拐凸起
佳木河组
储集层
浊沸石
胶结物
假粒缘缝
物性校正
Junggar basin
Zhongguai uplift
Jiamuhe formation
reservoir
laumontite
cement
pseudo granular marginal fracture
physical property correction