川西龙门山前雷口坡组四段储层特征及形成机理

摘要

川西龙门山前中三叠统雷口坡组雷四上亚段发育厚达百余米的潮坪相白云岩溶蚀孔隙型储层,可分为上、下2个储层段.对钻井岩心、薄片和物性分析表明,以白云岩类为主的下储层段优质储层呈多层叠置分布,储集性能优于灰质含量较多的上储层段.根据不同类型岩石物性统计及储层储集空间特征分析,结合扫描电镜、包裹体分析等技术对储层成因进行研究,认为"白云岩化+准同生期溶蚀+埋藏溶蚀"叠加形成了该套优质储层,其中,区域分布的潮坪相白云岩为储层的稳定广泛分布奠定了重要岩性基础;准同生期溶蚀控制了优质储层多层叠置分布;埋藏溶蚀叠加改造有利于孔隙的保持及储层渗透率的改善,进一步提高了储层的品质.%Over one hundred meters of tidal-flat facies dolomite with dissolution-pores developed in the Middle Triassic Leikoupo Formation in the Longmen Mountain front in the western Sichuan Basin.It can be further divided into the upper and lower reservoirs.The analyses of well cores, debris, thin sections and physical properties show that the properties of the lower reservoir, dominated by superposed dolomites, are better than those in the upper reservoir, dominated by limestones.The reservoir formation mechanism was studied using SEM and inclusion homogenization temperature analyses based on rock physical property statistics and reservoir space characteristics.Dolomitization, dissolution in the penecontemporaneous period and dissolution during the burial period formed this good reservoir.Widely distributed dolomites, which developed in a tidal-flat facies, established an important foundation for a steady distribution of reservoirs, dissolution in the penecontemporaneous period determined the formation and distribution of good reservoirs, and dissolution in burial period was favorable for the retention of pores and the increase in permeability, further improving reservoir quality.