Integration of diagenesis, porosity evolution, and oil emplacement in lacustrine tight sandstone reservoirs: A review with illustrative cases from the major oil-bearing basins in China
ABSTRACT
Tight sandstone oil is currently one of the most important unconventionalhydrocarbon resources in China. The coupling relationshipbetween porosity evolution and oil emplacement determinesthe reservoir effectiveness and oil exploration potential in tightsandstones. Complex diagenetic alterations, however, makeresearch on porosity evolution much more difficult than that onconventional sandstone reservoirs. This study examines the typicallacustrine tight sandstones from western to eastern China. Thereservoir lithologies, characteristics, and paragenetic sequences ofthe diagenesis are reviewed, and an integrated analysis of diagenesis,porosity evolution, and oil emplacement is proposed.
Results demonstrate that diagenesis is influenced by rockcomposition and lithological associations. For example, calcitecementation is primarily controlled by the distance to thesandstone–mudstone interface, whereas zeolite cements arerelated to volcanic rock fragments. Furthermore, we established aporosity evolution recovery method with respect to the paleoburialdepth (or time) of major diagenetic events, including the evaluationof the relationship between the thin section and heliumporosity and oil emplacement. We clarified the formation time and the underlying mechanisms. Three typical examples from themajor oil-bearing basins in China were chosen to analyze the integrationprocess of diagenesis, the porosity evolution of tight sandstones,as well as the coupling relationship between porosityevolution and oil emplacement. Tight sandstones characterizedby different diagenetic alterations exhibit different coupling relationshipsbetween porosity evolution and oil emplacement. Ourstudy can provide important guidance for reservoir quality predictionand oil exploration potential evaluation.
ABSTRACT
Tight sandstone oil is currently one of the most important unconventionalhydrocarbon resources in China. The coupling relationshipbetween porosity evolution and oil emplacement determinesthe reservoir effectiveness and oil exploration potential in tightsandstones. Complex diagenetic alterations, however, makeresearch on porosity evolution much more difficult than that onconventional sandstone reservoirs. This study examines the typicallacustrine tight sandstones from western to eastern China. Thereservoir lithologies, characteristics, and paragenetic sequences ofthe diagenesis are reviewed, and an integrated analysis of diagenesis,porosity evolution, and oil emplacement is proposed.
Results demonstrate that diagenesis is influenced by rockcomposition and lithological associations. For example, calcitecementation is primarily controlled by the distance to thesandstone–mudstone interface, whereas zeolite cements arerelated to volcanic rock fragments. Furthermore, we established aporosity evolution recovery method with respect to the paleoburialdepth (or time) of major diagenetic events, including the evaluationof the relationship between the thin section and heliumporosity and oil emplacement. We clarified the formation time and the underlying mechanisms. Three typical examples from themajor oil-bearing basins in China were chosen to analyze the integrationprocess of diagenesis, the porosity evolution of tight sandstones,as well as the coupling relationship between porosityevolution and oil emplacement. Tight sandstones characterizedby different diagenetic alterations exhibit different coupling relationshipsbetween porosity evolution and oil emplacement. Ourstudy can provide important guidance for reservoir quality predictionand oil exploration potential evaluation.
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