寻找新油气藏的理论和方法

石油深部起源理论认为,石油、天然气与金属矿床一样都是地球排气作用的产物。含油气盆地的演化与地球外核的排气及表面的升降变化相呼应,表明了含油气盆地的深部构造本质。石油及天然气形成于地球排气作用出现冷分支的新生代,明显表现为热液期后的特征。油气以垂直运移为主聚集在流体动力学构造圈闭以及与此有关的地层、岩性圈闭中,与新构造运动关系密切,这些理论为寻找新油气藏指明了方向。中国含油气盆地的特点是盆地基底深,沉积地层厚度大,故在已发现油气藏以下地层直至基底内部都有望发现新的油气藏。在新构造运动活跃、深部脆性岩石发育、具有良好盖层形成圈闭的地区,应首先采用深部地震对以构造裂隙油气藏为目标进行勘探。需要指出的是,传统的地震勘探方法对于查明深部断裂、高孔隙带和裂隙带是无能为力的,亟需开发非传统的地震勘探方法,此外,还可结合遥感、地球化学、张量分析、放射性、形态构造模拟等方法。

Theories and Methods for Exploration of New Oil/Gas Reservoirs

The theory of oil originated from deep of the earth considered that oil/gas,like the metal mineral deposits,is the product of degasification within the earth.The geological evolution history of an oil-bearing basin is in response to the earth surface uplift and subsiding and the degasification of the earth’s outer core,which reveals the deep structure property of oil-bearing basin.Oil/gas formed from degasification of the earth during the Cenozoic shows characteristics of post-hydrothermal process.Oil/gas dominated by vertical migration is normally accumulated at structural traps and related stratigraphic and lithologic traps,which had closed relationship with neotectonics.Such a theory can be applied to searching for new oil/gas reservoirs.China’s oil-bearing basins are characterized by deep burial basement and thick sedimentary strata,which indicate that new oil/gas reservoirs could be found from the strata under the discovered oil/gas pools to the basement.Structural fractured oil/gas reservoirs would be the main targets for exploration in areas with active neotectonics,deep brittle rocks and good cap rocks.The deep seismic survey should be the main method for exploration of them.However,the traditional seismic survey is helpless for detection of deep faults and rock bodies with high porosity and highly fractured belts.Such non-traditional seismic prospecting methods as telemetry,geochemistry,tensor analysis,radioassay and structural configuration modeling,etc.could also be used for it as necessary.