高邮凹陷南断阶致密砂岩储层评价方法

Evaluation method for tight sandstone reservoir in south fault terrace of Gaoyou Sag

储层评价对致密砂岩油藏的有效开发至关重要。在总结前人致密砂岩储层评价方法的基础上,针对高邮凹陷南断阶致密砂岩储层特征,通过取心井与常规井结合,测井与地质结合,常规实验与特殊实验技术结合,从致密砂岩储层成因入手,分析储层的储集能力和渗流能力,由特殊向普遍推广延伸评价,探索相对优势储层。研究表明:南断阶致密砂岩储层成因主要为胶结作用,胶结物主要为碳酸盐类的方解石和白云石。不同渗透率级别的储层,渗透率越高,储层潜力越大;相同渗透率级别的储层,中等胶结类潜力优于强胶结类。自然电位幅度差≥20 mV,声波时差值≤235μs/m的储层属于致密砂岩储层;声波时差值为225~235μs/m的储层属于致密砂岩中的相对优势储层。

Effective tight sandstone reservoir development depends on reservoir evaluation.According to the characteristics of tight sandstone reservoirs in the southern fault stage of Gaoyou Sag,through a combination of coring wells and conventional wells,logging and geology,and conventional experiments and special experimental techniques,starting from the genetic analysis of tight sandstone reservoirs,the reservoir capacity and seepage capacity of the reservoirs are analyzed based on a summary of previous evaluation methods of tight sandstone reservoirs.The special to the general evaluation is expanded,and the relatively favorable reservoirs are investigated.According to the findings,cementation is primarily responsible for forming the tight sandstone reservoirs in the south step-fault,and the cement is made primarily of calcite and dolomite.The potential of a reservoir increases with increasing permeability for reservoirs with different levels of permeability.A medium cement reservoir has greater potential than a strong cement reservoir for reservoirs with the same level of permeability.The tight sandstone reservoir has an acoustic value of less than or equal to 235μs/m and a spontaneous potential differential larger than or equal to 20 mV.The reservoirs with the acoustic time difference of 225-235μs/m belong to the relatively dominant reservoirs in the tight sandstone.