Article

Petroleum Geology & Experiment

, 37:8

First online:

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Characteristics, origin and quantitative evaluation of overpressure in strike-slip and compression-shear booster zone of Tan-Lu Fault:

  • Ajuan WeiAffiliated withExploration and Development Research Institute of CNOOCTianjin Branch

Abstract

In the JZ27-A well block of the strike-slip and compression-shear booster zone in the JZ27 section of the Liaodong Bay in the Bohai Sea area of the Tan-Lu Fault, overpressure developed in the third member of the Shahejie Formation, and the pressure coefficient reached an average of 1.5. Thick mudstones sealed the overpressure on the top. Particle fragmentation was obvious in the overpressure zone. The area and thickness of the overpressure were controlled by the range of the pressure booster zone and the intense development of strike-slip and compression-shear zone, mainly restricted to the third member of the Shahejie Formation in the JZ27-A well block. The origin for overpressure was interpreted to be as follows. From the end of the third member of the Dongying Formation to the early stage of the second member of the Dongying Formation, influenced by the intense dextral strike-slip of the Tan-Lu Fault, stress concentrated in the JZ27-A well block of the strike-slip and compression-shear booster zone. Thereby, horizontal structural compression stress formed. At the same time, because of overlying thick-bedded mudstones, stress could not be released effectively. As a result, overpressure occurred. According to the balance of reservoir pressure, the contribution of strike-slip stress to overpressure was quantitatively evaluated. The contribution of strike - slip stress to overpressure was 30% - 35% and occurred earlier than the period with large amounts of hydrocarbon generation and expulsion. The overpressure impeded the charging of oil tremendously.

Key words:

quantitative evaluation; origin of overpressure; strike-slip and compression-shear booster zone; Tan-Lu Fault; Liaodong Bay

郯庐断裂增压带超压特征、成因及其定量评价