珠江口盆地珠一坳陷地温-地压系统特征及其对油气分布的影响

盆地地温和地压对油气成藏有重要的控制作用。针对珠江口盆地珠一坳陷的地温—地压系统特征研究薄弱的问题，以实测数据为基础，应用地温—地压系统概念，分析珠一坳陷3个典型凹陷的地温、地压及地温—地压系统特征，探讨其成因并分析其与油气分布的关系。认为珠一坳陷地温梯度表现为浅层低而深层高的特征；地压场表现为恩平组发育弱超压，文昌组发育中幅超压；珠一坳陷发育高压型复式地温—地压系统，即浅层为静压型地温—地压系统，深层为高压型地温—地压系统。迄今为止，珠一坳陷已发现的油气藏集中在浅部层系，以断层油气藏为主，而根据高压型复式地温—地压系统的基本特征，预测深部层系中极有可能发育与断裂活动无关的超压型岩性油气藏。显然查明地温—地压系统分布特征对珠一坳陷油气藏分布预测及勘探部署具有十分重要的指导意义。

Characteristics of Geotemperature Pressure System and Their Influence on Hydrocarbon Distribution in Zhuyi Depression,Pearl River Mouth Basin

Geotemperature and pressure have a great controlling function on hydrocarbon generation, migration and accumulation. The characteristics of geotemperature pressure system in Zhuyi Depression, Pearl River Mouth Basin are under researched. By theory of geotemperature pressure system, the geotemperature, formation pressure and geotemperature pressure system in three typical sags are characterized and their relationship with hydrocarbon distribution is explored based on measured data. Research shows that Zhuyi Depression is characterized by rising geothermal gradient from top to bottom and rising overpressure extent with Enping Formation developing slight overpressure and Wenchang Formation developing moderate overpressure. Overpressure composite geotemperature pressure system develops in Zhuyi Depression, namely normal geotemperature pressure system of shallow layers and overpressure system of deep layers. So far the reservoirs discovered in Zhuyi Depression are mainly fault reservoirs distributed in shallow and middle layers. However, it is highly possible that overpressure lithological reservoirs are developed in deep layers, which is predicted according to the basic characteristics of overpressure composite geotemperature pressure system. Finding out the characteristics of geotemperature pressure system is quite instructive in predicting hydrocarbon distribution and making exploration deployment in Zhuyi Depression.