塔中东部上奥陶统礁滩体古岩溶特征及发育模式

Paleokarst Characteristics and Development Patterns of Upper Ordovician Reef Flat Complex in Eastern Tazhong Area, Tarim Basin

基于塔中东部地区上奥陶统良里塔格组沉积背景和构造特征研究,结合钻井、岩心、测井及地球化学等资料分析,认为良三段—良二段沉积期以高位体系域垂向持续加积作用为主,是礁(丘)、滩组合镶边沉积的主要发育期,受多期礁滩体营建和海平面升降的控制,礁滩体垂向上溶蚀、胶结作用分带性明显,孔隙发育带集中分布于大气渗流带及潜流带上部近潜水面处,胶结作用带发育于海底潜流带下部。大气淡水选择性溶蚀作用形成的大气成岩透镜体集中分布于礁型沉积地貌隆起区的各期礁滩沉积旋回的中上部,形成以粒内溶孔、铸模孔和粒间溶孔为主的有效储渗空间,区域上呈透镜状沿台地边缘高能相带断续分布。揭示了礁滩体同生期岩溶特征、控储机制及发育模式。

Based on study of sedimentary setting and structural feature of Lianglitage formation, integrated with analyses of drilling, core, well logging and geochemical data, the sedimentation of Lianglitage No.3 to No.2 members of the Upper Ordovician is dominated by contin- ually vertical accumulation during highstand system track, which is the main development period of reef-flat complex. The vertical zonality of denudation and cementation in the reef-flat complex is obvious under control of the multi-phase reef-flat complex constructions and eu- static secondary cycles, and the secondary pore spaces mainly develop in the atmospheric vadose zone and upper phreatie zone, while ce- mentation occurs in the bottom of phreatic zone. Atmospheric diagenetic lens formed by selective denudation are mainly distributed in the middle-upper parts of the individual phase of reef-flat sedimentary cycles, which becomes the effective storage and seepage spaces corn- / posed of intragranular solution pore, moldic pore, intergranular solution pore, and intermittently distributed along the high energy facies belts of the rimmed platform. The syngenetic paleokarst feature, the reservoir control mechanism and development model of reef-fiat com- plex in this area are revealed in this paper.