Fluid mapping in deeply buried Ordovician Paleokarst reservoirs in the Tarim Basin, Western China
Fluid mapping in deeply buried Ordovician Paleokarst reservoirs in the Tarim Basin, Western China
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DOI：
10.1111/gfl.12160
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发表时间：
2016-08
期刊：
影响因子：
1.7
通讯作者：
Y. Zhang;Zhixue Sun;Han Jianfa;Wang Haoxuan;C. Fan
中科院分区：
文献类型：
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作者：
Y. Zhang;Zhixue Sun;Han Jianfa;Wang Haoxuan;C. Fan
塔里木盆地深层奥陶系古岩溶储层的储集空间以次生储集空间为主，具有较强的非均质性和一定的各向异性。充填这些储层空间的流体类型对油气勘探和开发具有重要意义。然而，在该地区，从地震数据中识别流体常常是有争议的，因为该特定储层的地震速度可能受到许多因素的显著影响，包括孔隙形状、孔隙度、流体类型和矿物含量。本研究采用微分有效介质-Gassmann岩石物理模型，利用测井资料对塔里木盆地常规岩溶型碳酸盐岩储层充注不同流体（油、气、水）的特征进行了解释和探讨，客观地建立了相应的流体识别标准。随后，利用典型测井资料进行振幅随炮检距（AVO）正演分析，对这些准则进行了评价，并根据叠前反演结果，进一步应用这些准则确定了塔里木盆地两个不同地区的储层流体类型。对于常规碳酸盐岩储层，可以将气体与重油和水区分开，但是重油和水在地震数据上大致相似。对于凝析碳酸盐岩储层，水可以与轻质油（即，凝析油）和天然气，但轻质油和天然气在地震响应方面表现出实质性的相似性。流体预测结果与钻井和试油结果吻合较好。特别是，对塔里木盆地碳酸盐岩地层中地震可分辨储层的建模表明，如果常规碳酸盐岩储层的孔隙度大于5%，凝析碳酸盐岩储层的孔隙度大于7%，则可以适当地评估流体性质，这些储层具有针状和球形储集空间（孔隙纵横比> 0.3），粘土含量低于5%。
The storage spaces within deeply buried Ordovician paleokarst reservoirs in the Tarim Basin are mostly secondary and characterized by strong heterogeneity and some degree of anisotropy. The types of fluids that fill the spaces within these reservoirs are of great importance for hydrocarbon exploration and exploitation. However, fluid identification from seismic data is often controversial in this area because the seismic velocity for this particular reservoir could be significantly influenced by many factors, including pore shapes, porosity, fluid types, and mineral contents. In this study, we employ the differential effective medium‐Gassmann rock physics model to interpret and discuss the characteristics of conventional karstic carbonate reservoirs in the Tarim Basin that are filled with different fluids (oil, gas, and water) using logging data and thus objectively build corresponding fluid identification criteria. These criteria are subsequently evaluated by amplitude versus offset (AVO) forward analysis based on typical logging data and further applied to ascertain the reservoir fluid types in two different areas in the Tarim Basin based on prestack inversion results. For conventional carbonate reservoirs, gas can be distinguished from heavy oil and water, but heavy oil and water are broadly similar on seismic data. For condensate carbonate reservoirs, water can be differentiated from light oil (i.e., condensates) and gas, but light oil and gas demonstrate substantial similarities in terms of their seismic responses. The predicted fluid results are in good agreement with the results of drilling and oil testing. In particular, modeling the seismically resolvable reservoirs in the carbonate strata in the Tarim Basin, which have needle‐ and sphere‐shaped storage spaces (pore aspect ratio > 0.3) and clay content that is lower than 5%, indicates that fluid properties could be properly evaluated if the porosity is larger than 5% for conventional carbonate reservoirs and >7% for condensate carbonate reservoirs.