地学前缘 ›› 2016, Vol. 23 ›› Issue (1): 206-217.DOI: 10.13745/j.esf.2016.01.019

• 页岩储层特征与评价 • 上一篇    下一篇

黔西北地区龙马溪组页岩气储层孔隙特征及其储气意义

史淼，于炳松，薛志鹏   

  1. 中国地质大学(北京) 地球科学与资源学院， 北京 100083
  • 收稿日期:2015-09-11 修回日期:2015-11-10 出版日期:2016-01-15 发布日期:2016-01-15
  • 作者简介:史淼(1987—)，女，博士研究生，矿物学、岩石学、矿床学专业，主要从事沉积学及非常规油气储层地质学研究。E-mail:miaoer727@126.com
  • 基金资助:

    高等学校博士学科点专项科研基金项目(20120022130001)；全国页岩气资源战略调查项目 (2009GYXQ15 - 03)；国家自然科学基金面上项目(41572134)

Pore characteristics and significance of the Longmaxi Formation gas shale reservoirs in northwestern Guizhou, China.

  • Received:2015-09-11 Revised:2015-11-10 Online:2016-01-15 Published:2016-01-15

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摘要：

中国南方下志留统龙马溪组海相页岩有机质含量高且热成熟度高，是重要的页岩气储集层位。本文以黔西北地区习页1井与桐页1井的岩心样品为研究对象，研究龙马溪组页岩的孔隙特征及孔隙发育的影响因素，并对其储气性能进行综合的分析与评价。通过扫描电镜的大量观察可知，该区龙马溪组页岩内发育的孔隙多为纳米(nm)量级，包含矿物基质孔(可分为粒间孔和粒内孔)、有机质孔以及微裂缝等多种类型的孔隙，其中有机质孔最为发育。通过测试可知，该区页岩的总有机碳(TOC)含量平均为3.80％，热成熟度(Ro)平均为2.73％，有效孔隙度平均为1.56％；主要组成矿物为黏土矿物与碎屑矿物(石英、长石等)，黏土矿物含量平均为32.42％，碎屑矿物含量平均为43.97％；BET比表面积平均为16.98 m2/g，BJH总孔体积平均为0.013 7 mL/g，孔隙的平均孔径为33.75 nm。通过分析可知，TOC含量为孔隙发育的主要影响因素，样品的有效孔隙度与TOC、碎屑矿物含量呈线性正相关关系，与黏土矿物含量呈线性负相关关系。另测得样品对甲烷气体的饱和吸附量平均为2.42 m3/t，饱和吸附量与TOC含量呈强烈的正相关性，TOC含量为吸附性能的主控因素；饱和吸附量与有效孔隙度、碎屑矿物含量、BET比表面积以及BJH总孔体积均呈明显的正相关性，而与黏土矿物含量的相关性不显著。

关键词: 黔西北, 龙马溪组, 孔隙类型, 影响因素, 储气

Abstract:

The Lower Silurian Longmaxi Formation marine shales, with high organic matter abundance and high thermal maturity, have been known as the main shale gas reservoirs in southern China. Pore characteristics and the influencing factors for pore development were investigated by samples collected from the Well Xiye1 and Well Tongye1 in northwestern Guizhou, China. FESEM implied that nearly all pores are nanometerscaled. Pores could be divided into mineral matrix pores (including interparticle pores and intraparticle pores), organic matter (OM) pores and microfracture pores. OM pores are the most prevalent ones within these shale samples. Results of other experiments show that the TOC content averages 3.80%; the Ro value averages 2.73%; and the total porosity averages 1.56%. The shales are rich in clay and detrital minerals (quartz and feldspar), with average contents of 32.42% and 43.97%, respectively. The average BET specific surface area is 16.98 m2/g; the BJH total pore volume is 0.0137 mL/g; and the pore diameter is 33.75 nm. Regression analyses suggest that the TOC content is the key influencing factor for pores development. The total porosity is positively correlated with TOC and detrital mineral content, but is negatively correlated with clay mineral content. Besides, saturated adsorption amount averages 2.42 m3/t and there is a strong positive linear correlation between saturated adsorption amount and the TOC content, which infers that OM pores may provide a main space for gas storage. Saturated adsorption amount also shows strong positive linear correlation to total porosity, detrital minerals content, the BET surface area, and the BJH total pore volume.

Key words: Northwestern Guizhou, Longmaxi Formation, pore types, influencing factors, gas storage

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