潜江凹陷蚌湖—周矶向斜带温压系统特征及油气分布

Characteristics of Geothermal-Geopressure System and Its Relationship with Oil and Gas Distribution in Banghu-Zhouji Syncline Belt in Qianjiang Sag

蚌湖—周矶向斜带是潜江凹陷最好的生烃向斜带,具有丰富的油气资源。利用90余口探井的实测温压数据,对蚌湖—周矶向斜带的地温场、地压场、温压系统纵横向分布特征进行了剖析,并探讨了它们与油气分布的关系。研究表明,蚌湖—周矶向斜带具有较高的地温梯度,有利于烃源岩成熟与油气生成;深部发育的弱超压可为油气运移提供重要的驱动力;纵向上具有高压型复式温压系统特征,但油气的垂向运移能力较差,以较短距离的侧向运移为主;平面上各含油层系的油藏主要分布于流体能量相对低能区,且环绕或紧邻相对高能区发育。

Banghu-Zhouji syncline belt is the best source belt in Qianjiang sag with abundant hydrocarbon resources.Based on the theory of geothermal-geopressure system and observed temperature-pressure data from more than 90 wells,this paper analyzes the plane and section characteristics of the geothermal field,geopressure field and geothermal-geopressure system in Banghu-Zhouji syncline belt as well as the relationship between these characteristics and hydrocarbon distribution.The research shows that the high geothermal gradient in Banghu-Zhouji syncline belt is propitious to the maturity of source rocks and generation of hydrocarbons;the deep low overpressure could be as the important motivating force for petroleum migration;vertically,it has the characteristic of overpressure complex geothermal-geopressure system,but the vertical migration capacity of hydrocarbons is weaker,being dominated by short-range lateral migration;laterally,various oil-bearing reservoirs are mainly distributed in the areas with relatively low fluid energy,which is surrounding or adjacent to the areas with relatively high fluid energy.