Diagenesis of the Triassic Yanchang Formation Tight Sandstone Reservoir in the Xifeng–Ansai Area of Ordos Basin and its Porosity Evolution
Diagenesis of the Triassic Yanchang Formation Tight Sandstone Reservoir in the Xifeng–Ansai Area of Ordos Basin and its Porosity Evolution
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DOI：
10.1111/1755-6724.12737
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发表时间：
2016-06
期刊：
影响因子：
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通讯作者：
Liu Mingjie;Liu Zhen;Wang Peng;Pan Gao-feng
中科院分区：
文献类型：
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作者：
Liu Mingjie;Liu Zhen;Wang Peng;Pan Gao-feng
本研究旨在揭示鄂尔多斯盆地西丰—安塞地区三叠系延长组致密砂岩储层孔隙度演化规律。基于砂岩储层的破坏性成岩作用（压实作用和胶结作用）和建设性成岩作用（溶蚀作用），分析了本区致密砂岩储层的成岩作用特征，并结合砂岩储层现今孔隙度剖面特征，探讨了砂岩成岩作用与孔隙演化的关系。利用效应模拟原理对延长组致密砂岩储层孔隙度演化进行了数学推导和模拟。结果表明：在延长组致密砂岩储层中，压实作用始终存在，当埋深增加到一定值时，胶结作用一直存在；溶蚀只发生在演化的某一阶段，具有窗口特征。在相应的现今孔隙剖面中，成岩作用以分段为特征。由浅至深依次发生压实作用、压实作用、胶结作用和溶蚀作用、压实作用和胶结作用。因此，砂岩孔隙度演化可分为正常压实段、酸化增孔段和溶蚀后正常压实段。结果表明，砂岩孔隙度演化可分为孔隙度减小模型和孔隙度增大模型。两种模型在三阶段或同一地质时期同一深度的叠加可构成砂岩储层总孔隙度的演化模拟。通过模拟西峰地区8段和安塞地区6段砂岩储层孔隙度的演化，发现两者在演化过程和趋势上具有相似性。这种差异是由区域隆起或下沉和埋深造成的。
This work aims to reveal the evolution of the porosity in the Triassic Yanchang Formation tight sandstone reservoir of the Xifeng–Ansai area of Ordos Basin. Based on destructive diagenesis (compaction and cementation) and constructive diagenesis (dissolution) of sandstone reservoirs, this study analyzed the diagenesis characteristics of the tight sandstone reservoirs in this area, and discussed the relationship between sandstone diagenesis and porosity evolution in combination with present porosity profile characteristics of sandstone reservoir. The effect simulation principle was employed for the mathematical derivation and simulation of the evolution of porosity in the Yanchang Formation tight sandstone reservoirs. The result shows that compaction always occurs in tight sandstone reservoirs in the Yanchang Formation, and cementation occurs when the burial depth increases to a certain value and remains ever since. Dissolution occurs only at a certain stage of the evolution with window features. In the corresponding present porosity profile, diagenesis is characterized by segmentation. From the shallow to the deep, compaction, compaction, cementation and dissolution, compaction and cementation occur successively. Therefore, the evolution of sandstone porosity can be divided into normal compaction section, acidification and incremental porosity section, and normal compaction section after dissolution. The results show that the evolution of sandstone porosity can be decomposed into porosity reduction model and porosity increase model. The superposition of the two models at the same depth in the three stages or in the same geological time can constitute the evolution simulation of the total porosity in sandstone reservoirs. By simulating the evolution of sandstone reservoir porosity of the eighth member in Xifeng area and the sixth member in Ansai area, it shows that they are similar in the evolution process and trend. The difference is caused by the regional uplift or subsidence and burial depth.