渝东南-黔北地区下寒武统牛蹄塘组页岩裂缝有效性研究  

Research on the fracture effectiveness of the Lower Cambrian Niutitang shale in the southeastern Chongqing and northern Guizhou areas

作　　者：曾维特[1] 丁文龙[2,3,4] 张金川[2,3,4] 李玉喜[5] 林拓[6] 王濡岳 付景龙 

机构地区：[1]海南省地质调查院,海南海口570206 [2]中国地质大学北京能源学院,北京100083 [3]中国地质大学北京页岩气勘查与评价国土资源部重点实验室,北京100083 [4]中国地质大学北京海相储层演化与油气富集机理教育部重点实验室,北京100083 [5]国土资源部矿产储量评审中心,北京100035 [6]中国地质调查局油气资源调查中心,北京100037 [7]中国石油华北油田公司勘探开发研究院,河北任丘062552

出　　处：《地学前缘》2016年第1期96-106,共11页Earth Science Frontiers

基　　金：国家自然科学基金面上项目(41372139,41072098,41272167,41002072);国家油气重大专项专题(2011ZX05018-001-002,2016ZX05046-003)

摘　　要：基于对研究区下寒武统牛蹄塘组页岩岩心裂缝观察描述,利用测井、区域地质资料定量研究裂缝有效性,对其主控因素进行定性分析,结合页岩岩心现场解吸实验,探讨页岩含气量与裂缝有效性关系。结果表明:牛蹄塘组页岩岩心裂缝发育,当裂缝开度大、角度陡倾、延伸较远时,深、浅侧向电阻率值差异明显,裂缝有效性高;若裂缝角度平缓、纵向上延伸较浅、开度小,深、浅侧向电阻率值无明显差异,裂缝有效性差,且多为矿物所封堵。页岩裂缝有效性主要受充填程度、溶蚀作用、异常流体高压、构造活动等因素控制。其中矿物封堵对裂缝有效性造成破坏较大;溶蚀作用和页岩中的异常流体高压对改善页岩孔渗、提高裂缝有效性有积极效果,区域构造活动对不同构造部位裂缝的有效性产生不同影响。有效裂缝有助于吸附态页岩气的解吸,增加游离气含量,成为天然气运移、开采的通道,特别对改善页岩储层渗透率作用更大。然而过大规模尺寸的裂缝会破坏页岩密封性和超压,使天然气散失,不利于页岩气保存。Based on the observation and description of Niutitang shale core fractures in southeast Chongqing and north Guizhou,the effectiveness of fractures was analyzed quantitatively by using logging and regional geological data, meanwhile,the controlling factors of natural fractures effectiveness were researched qualitatively.The relationship between shale gas content and fractures effectiveness was discussed based on the desorption experiments of shale core.The results show that fractures are abundant in Niutitang shale core.The significant difference between deep laterolog resistivity values and shallow laterolog resistivity values revealed the high effectiveness of natural fractures with wild aperture,steep angle and far extending in longitudinal.On the contrary,the low effectiveness of natural fractures due to low angle,narrow aperture,mineral sealing and closely extending in longitudinal,caused the unconspicuous difference between deep laterolog resistivity values and shallow laterolog resistivity values.The effectiveness of fractures is mainly controlled by mineral sealing,denudation,abnormal fluid pressure and tectonic movement.Among them,mineral sealing in fractures caused major damage to the effectiveness,denudation and high abnormal fluidpressure improved the porosity and permeability of shale,thereby improved the effectiveness.The regional tectonic activity produced different effects to the fractures which are in different parts of tectonic position.The effective fractures contributed to the desorption of shale gas,hence the free gas content increased.Moreover,the effective fractures could be the channels for gas migration and exploitation, which improved the permeability of shale reservoir.However,natural fractures with large scale would destroy the sealing property and overpressure of shale reservoir,which will result in the loss of natural gas,therefore,it is not conducive to the preservation of shale gas.

关 键 词：渝东南 黔北 牛蹄塘组 页岩 裂缝 有效性 

分 类 号：P618.130.21[天文地球—矿床学]