塔中地区奥陶系碳酸盐岩埋藏溶蚀特征及初步预测

摘要

塔中地区奥陶系碳酸盐岩发育多种形式岩溶作用,其中埋藏溶蚀是形成有利储层的重要机制之一.录井岩心分析化验资料及宏观地质背景分析表明,塔中地区奥陶系碳酸盐岩主要发育4期埋藏溶蚀,其中Ⅰ、Ⅱ期溶蚀孔洞基本已被充填,Ⅲ期残留部分孔隙和Ⅳ期溶蚀孔洞为现今储层有效储集空间.上奥陶统良里塔格组现今未被充填的粒内溶孔及铸模孔可能主要形成于埋藏溶蚀,并非准同生溶蚀.埋藏溶蚀发生的流体介质主要为有机质演化过程中形成的有机酸和CO2,在更深部或经历更高热史经历的区域,H2S对储层的形成可能会有较大贡献,热水-热液溶蚀对储集空间贡献有限.初步分析表明,卡塔克隆起西北部埋藏溶蚀孔隙较发育,塔中南部台地边缘带可能是埋藏溶蚀另一相对较发育地区.%Various types of karstification effects have developed in the Ordovician carbonatere servoirs of the central Tarim Basin.The deep burial and hydrothermal Karstification effects play important roles in favorable reservoir formation. Analyses of well cores.logging data and geol ogical background have indicated that,there are mainly 4 stages of burial Karstification effects in the area.The pores in stages I and 11 have been filled.The residual pores in stage HI and the corrosion pores in stage IV work as effective reservoir space for present reservoirs.The main flud medium include organic acid and CO2 generated during organic evolution.H2S may contribute to late reservoir formation.Hydrothermal Karstification is effective to Ordovician reservoir transformation.The influence and evaluation still require further research.Preliminary analysis shows burial karstification pores is development in northwest of central Tarim Basin.the next oen is plateform margin in south of central Tarim Basin.