摘要
龙马溪组页岩是现阶段国内勘探的主要层位之一。川南扬子地区下古生界的龙马溪组气层存在低电阻率特征,仅从测井响应上很难与水层区别。为此,在现有常规测井、钻井取心、生产动态等资料的基础上,结合大量铸体薄片、QEMSCAN和X全岩衍射等岩心分析实验,对该地区低阻气层的成因机制进行了深入研究,结果表明:川南扬子地区下古生界的龙马溪组低阻气层的主控因素有3个:黏土矿物的附加导电性、过成熟有机质完全石墨化和有机质纹层分布形式。实际应用结果表明:研究区低阻气层的成因为发育的有机质纹层和有机质部分石墨化,即页岩气储层表现为低阻往往都是多种因素相互叠加、相互影响造成的,在分析时需要根据不同地区、不同层段分析相应地质、测井和岩心资料,并且需要利用上下层段对比和邻井对比等方法判断储层低阻的主控因素。
The Longmaxi Formation is one of the major exploration horizons of shale in China at present.The gas-bearing sediments in the Lower Paleozoic Longmaxi Formation in the Yangtze area,South Sichuan are characterized by low resistivity.Therefore,it is difficult to distinguish the gas-bearing sediments from aquifers only using logging response.Given this,this study investigated the genetic mechanisms of low-resistivity gas-bearing sediments in the study area in depth using existing data of conventional logging,core drilling,and production-related dynamic conditions,as well as a large number of core analyses and experiments,including casting thin sections,QEMSCAN,and X whole-rock diffraction.According to the study results,three major controlling factors in the low-resistivity gas-bearing sediments of the Lower Paleozoic Longmaxi Formation in the Yangtze region,South Sichuan include the additional conductivity of clay minerals,the complete graphitization of over-mature organic matter,and the distribution pattern of organic matter laminae.The practical application results indicate that the low-resistivity gas-bearing sediments in the study area were formed due to the organic matter laminae developing and the partial graphitization of organic matter.That is,the low resistivity of the shale gas reservoirs tends to be caused by the mutual superimposition and effects of multiple factors.Therefore,it is necessary to analyze the geological,logging,and core data according to various zones and horizons and employ the correlation between upper and lower horizons and between adjacent wells to determine the major controlling factors of the low resistivity of the shale gas reservoirs.
作者
崔瑞康
孙建孟
刘行军
文晓峰
CUI Rui-Kang;SUN Jian-Meng;LIU Xing-Jun;WEN Xiao-Feng(China University of Petroleum(East China),Qingdao 266580,China;Changqing Branch,China National Logging Corporation,Xi'an 710065,China)
出处
《物探与化探》
CAS
北大核心
2022年第1期150-159,共10页
Geophysical and Geochemical Exploration
基金
国家科技重大专项(2017ZX05036-005-003)
国家自然科学基金项目(41874138)。
关键词
页岩气
低阻岩层
测井评价
影响因素
shale gas
low-resistivity formation
logging evaluation
influencing factors
