滇东威信地区龙潭组致密砂岩矿物组成特征及其油气地质意义  

Mineral composition characteristics and petroleum geological significance of tight sandstone of Longtan Formation in Weixin area,eastern Yunnan

作　　者：邢慧通 张晓丽[1,2] 何金先[1,2] 曹文杰[1,2] 杨甜甜 王健 师帅[1,2] XING Huitong;ZHANG Xiaoli;HE Jinxian;CAO Wenjie;YANG Tiantian;WANG Jian;SHI Shuai(Key Laboratory of Coalbed Methane Resources and Accumulation Process of Ministry of Education,China University of Mining and Technology,Xuzhou 221116,China;School of Resources and Geosciences,China University of Mining and Technology,Xuzhou 221116,China)

机构地区：[1]中国矿业大学煤层气资源与成藏过程教育部重点实验室,江苏徐州221116 [2]中国矿业大学资源与地球科学学院,江苏徐州221116

出　　处：《煤田地质与勘探》2022年第4期52-60,共9页Coal Geology & Exploration

基　　金：国家自然科学基金项目(41702170);中国博士后科学基金项目(2015M571841)。

摘　　要：致密气是发育于低孔、特低渗透砂岩中的一种非常规资源,具有丰富的潜在油气储量,但由于其致密低渗透性,压裂改造是致密气高效开发的必须手段,而砂岩储集特征及物质组成对初步评价致密砂岩储层的资源潜力和生产能力有重要意义。运用X射线衍射、显微镜及扫描电镜等技术手段,对滇东威信地区二叠系龙潭组10个致密砂岩露头样品进行定性和定量分析。结果表明,龙潭组致密砂岩矿物组分以黏土矿物和石英为主,平均质量分数分别为42.5%和30.1%;其次为长石,平均含量14.7%;另外,还含有少量的方解石和锐钛矿,虽然在部分样品中有检出,但其平均含量分别达到9.05%和14.4%。通过矿物组分法获得龙潭组致密砂岩的岩石脆性指数为0.575,脆性效果较好,有利于压裂。黏土矿物组合特征反映出龙潭组砂岩为深层低渗透砂岩储集层,物质来源与岩浆热液及玄武岩的风化产物有关。研究区龙潭组致密砂岩储层为高黏土矿物储层,尤其是绿泥石、高岭石的普遍存在,对孔隙发育有消极作用,影响煤系气的运移与储存,总体上属于深层低渗透高黏土矿物砂岩储层。但龙潭组上段高含量的碳酸盐类矿物,充填在孔裂隙中,对砂岩具有较强的抗压实作用,也是后期溶蚀作用的物质基础,易形成次生孔隙,对致密砂岩气藏的形成和开发有一定的促进作用,因此,龙潭组上段可作为下一步致密砂岩储层改造和致密气开发的首选层段。Tight gas is an unconventional resource developed in low-porosity and ultra-low permeability sandstone and has rich potential oil and gas reserves.However,due to its tight and low permeability,fracturing is a necessary means for efficient development of tight gas.The reservoir characteristics and material composition of sandstone are of great significance to the preliminary evaluation of resource potential and production capacity of the dense sandstone reservoirs.By using X-ray diffraction,microscopy,scanning electron microscopy and other technical means,ten outcroppings of tight sandstone from coal measures of Permian Longtan Formation in Weixin area of eastern Yunnan Province were qualitatively and quantitatively analyzed.The results show that the mineral components of tight sandstone in Longtan Formation are mainly clay minerals and quartz,with an average content of 42.5% and 30.1%respectively,followed by feldspar with an average content of 14.7%.In addition,a small amount of calcite and anatase are found in some samples,with an average content of 9.05% and 14.4% respectively.The brittleness index of Longtan Formation tight sandstone is 0.575 obtained by the mineral component method,which is favorable for hydraulic fracturing.The characteristics of clay mineral assemblage show that the Longtan Formation sandstone is a deep and low permeability sandstone reservoir,and the material source is related to the weathering products of magmatic hydrothermal and basalt.The tight sandstone reservoirs of Longtan Formation in the study area are high clay mineral reservoirs,and especially the widespread chlorite and kaolinite have a negative effect on pore development and affect the migration and storage of coal measure gas.Generally,it belongs to a deep low-permeability high clay mineral sandstone reservoir.However,the high content of carbonate minerals in the upper part of Longtan Formation,filled in pores and fissures,has strong anti-compaction effect on sandstone and is also the material basis of later dissolution.It is

关 键 词：致密砂岩 储层特征 矿物成分 X射线 龙潭组 滇东威信 

分 类 号：TE12[石油与天然气工程—油气勘探]