藏北羌塘盆地中上侏罗统碎屑岩储层成岩演化特征

运用分析化验、储层测试等多种资料 ,对羌塘盆地中上侏罗统碎屑岩储层的成岩演化特征进行了研究。将中上侏罗统地层划分为晚成岩期A亚期、B亚期和C亚期 3个成岩阶段 ,识别出压实作用、压溶作用、胶结作用、交代作用、次生溶蚀作用、重结晶作用、沥青充填作用和破裂作用等 7种成岩作用 ,以及机械压实成岩相、碳酸盐胶结成岩相、强压实压溶成岩相、不稳定组分溶解溶蚀成岩相和沥青充填成岩相等 5种成岩相类型。探讨了各种成岩相的岩性、物性等微观特征及其与沉积相类型之间的关系 ,总结出 3种成岩演化序列。分析结果表明 ,不同成岩作用类型对储层物性的影响不同 ,次生溶蚀作用、破裂作用使物性变好 ;压实作用、压溶作用和沥青充填作用使物性变差 ;胶结作用具有双重影响

DIAGENETIC EVOLUTION OF CLASTIC RESERVOIRS IN THE UPPER AND MIDDLE JURASSIC IN QIANGTANG BASIN OF NORTHERN XIZANG AREA

Characteristics of Diagenetic evolution of clastic reservoir in the upper and middle Jurassic in Qiangtang basin are studied using data from chemical examination and reservoir measurement. Three diagenetic stages in the upper and middle Jurassic are divided as A subphase of late diagenesis, B subphase of late diagenesis and C subphase of early diagenesis. Seven types of diageneses are recognized, including compaction, pressure solution, cementation, metasomasis, secondary corrosion, recrystallization, asphaltic packing and cracking. Five types of diagenetic facies are recognized, including mechanical compaction, carbonate cementation, strong compation and pressure solution, solution of unstable component and asphaltic packing. The relations among microstructures of each diagenetic facies, mainly including lithology, porosity and permeability, and the types of sedimentary facies are studied. Three types of successions of diagenetic evolution are summed.