银—额盆地查干凹陷温压场特征及其油气地质意义

CHARACTERISTICS OF THE TEMPERATURE AND PRESSURE FIELDS IN CHAGAN SAG OF YINGEN-EJINA BANNER BASIN AND THEIR PETROLEUM GEOLOGICAL SIGNIFICANCE

查干凹陷构造演化历史复杂 ,后期改造强烈 ,具有独特的温压场特征 ,并具有重要的油气地质意义。研究表明 ,查干凹陷中心的地温梯度高于凹陷边缘 ,大地构造性质及所处构造部位、岩性与地下水活动的差异是影响凹陷地温场分布特征的主要因素 ;泥岩压实存在正常压实、欠压实和过压实三种类型 ,砂岩储层段压力类型可分为正常和负压两个系统 ,地层抬升剥蚀是导致储层负压系统形成的主导因素 ;凹陷独特的温压场特征对烃源岩成熟、油气生成。

The tectonic evolution history of Chagan sag is complicated with a strong reformation in its later stage and this sag is of distinctive temperature-pressure field characteristics, which has important petroleum geological significance. Through studying it is shown that in Chagan sag, the geothermal gradients in the center are higher than those around the sag margin and major factors influencing the characteristics of temperature field distribution are the property of geotectogenesis and the differences in tectonic portion, lithology and underground water behaviour; there are three types of mudstone compaction, i.e. normal compaction, undercompaction and overcompaction; there are two pressure systems in sandstone reservoirs, i.e. normal pressure and negative pressure systems and the strata's being uplifted and denuded is the key factor leading to the formation of the negative pressure system in reservoir; and the distinctive temperature-pressure field characteristics in the sag are possessed of important petroleum geological significance in hydrocarbon source maturity, hydrocarbon generation, widening on oil and gas exploration domain and selecting exploration targets, etc.