南海北部深水区白云凹陷地温-地压系统特征及其石油地质意义

Characteristics of Geotemperature-Pressure Systems and Their Implications for Petroleum Geology at Baiyun Depression,Deep-Water Area of Northern South China Sea

南海北部深水区白云凹陷具有典型的高温高压特征.应用地温-地压系统概念,分析白云凹陷地层温度、地层压力及地温-地压系统在纵向上和平面上的分布特征,并探讨其与油气分布的关系.研究认为白云凹陷发育高压型复式地温-地压系统,即浅部为静压型地温-地压系统,深部为高压型地温-地压系统.同时将地层温度与地层压力进行平面耦合,在平面上将白云凹陷划分为6种地温-地压系统分区,白云凹陷北坡位于高温常压区和高温高压区,主洼带主体处在超高温高压区,主洼中心位于超高温超高压区,南坡位于高温高压区.已发现天然气藏主要分布在地温-地压系统的相对低能区.白云凹陷独特的高压型地温-地压系统可为油气运移提供超强动力,并控制油气藏分布.

Baiyun depression is characterized by high geotemperature and high pressure formation.By theory of geotemperature-pressure system,the geotemperature,formation pressure and geotemperature-pressure system at Baiyun depression and their relationships with hydrocarbon distribution are analyzed in vertical and lateral sections.Research shows that overpressure composite geotemperature-pressure system develops at Baiyun depression,namely normal geotemperature-pressure system of shallow zone and overpressure system of deep zone.Based on coupling characteristics of geotemperature and pressure,Baiyun depression is divided into six geotemperature-pressure system divisions.The northern slope belt is located in the area with high temperature and normal pressure,as well as high temperature and high pressure.The main sag is mainly located in the area with ultra high temperature and high pressure,and the center belt belongs to ultra high temperature and ultra high pressure region.The southern slope belt is located in the area with high temperature and high pressure.Natural gas pools are mainly distributed in relative low energy area.The special characteristics of geotemperature-pressure system at Baiyun depression provide strong power for hydrocarbon migration,and control the distribution of oil and gas reservoirs.