塔里木盆地塔中地区上奥陶统礁滩体基质次生孔隙成因——以塔中62井区为例

应用多种镜下微观分析方法，探讨塔中地区塔中一号带上奥陶统良里塔格组礁滩体基质次生孔隙的形成机理，并依据成岩演化序列进行了追踪分析。研究认为，该区良里塔格组储集层基质次生孔隙主要形成于中一深埋藏环境下的中成岩阶段：塔中一号断裂带沟通了中寒武统膏岩层和中下寒武统烃源岩层，在高温下发生硫酸盐热化学还原反应（TSR），产生的高温、高H2S含量的溶液沿断层和破裂带进入储集层进行溶蚀（被溶蚀组分以含藻或藻粘结的泥晶灰岩砂屑和渗流粉砂为主），形成了以粒内溶孔、铸模孔和粒间溶孔为主的基质次生孔隙。台地边缘的粒屑滩亚相是易溶组分的富集带，即形成基质次生孔隙的有利相带，因此该亚相内裂隙体系发育带是优质储集层有利分布区。图9参13

Genesis of reef flat body matrix secondary pores in Upper Ordovician in central area of Tarim Basin: A case from Well 62 field of Central Tarim

Through several microanalysis methods under microscope, the genetic mechanism of reef flat matrix secondary pores in the Ordovician Lianglitage Formation in No.1 structural belt of Central Tarim Basin was traced and analyzed according to diagenetic evolutionary series. The matrix secondary pores are generated in the middle diagenetic stage under the middle-deep buried condition, which is associated with high-temperature and high H2S content solution caused by TSR from the deep section. The solution enters along faults and fracture zones and corrodes reservoirs, and the corroded components are algal grains (or algal cement) bearing micritic limestone arene and filtrational silts. As a result, the matrix secondary pores are generated in types of intragranular dissolved pore, foundry pore and intergranular dissolved pore. Grain beaches in platform margins, reef flanks and hillocks are abundance zones for soluble components and favorable belts for generating matrix secondary pores. The development zones of fissure systems in these areas are potential for high-quality reservoirs.