新疆吐-哈盆地三叠系和侏罗系含油砂体的形成条件

吐-哈盆地是位于天山造山带内的具复杂演化历史的中新生代叠合盆地,是典型的煤成烃陆相含油气盆地。盆地南带的前侏罗系 (三叠系 )油气藏其含油砂体的形成明显受沉积相、高地温和印支运动的影响,分布于盆地南部的扇三角洲砂体裙在印支运动中由于地层抬升而处于与盆地北部生烃中心接触良好的位置,并且具备了产生次生孔隙的动力学基础,从而及时接受了由于岩浆体热和印支构造热事件提供的热所形成的早成熟油,形成了该盆地第一套优质储油砂体。盆地北带的侏罗系油气藏其含油砂体以南物源辫状河三角洲相为主,次为北物源扇三角洲相,具有砂体层数多、上下叠置性强、原始物性好、与多层煤系烃源岩互层、烃类向南运移距离短的特点,形成以中侏罗统西山窑组、三间房组和七克台组为基础的第二、三、四套优质储油砂体。

Formation Conditions of the Oil-Bearing Sandbodies of Triassic and Jurassic in Turpan-Hami Basin,Xinjiang

Turpan Hami basin is a Mesozoic Cenozoic compound basin with a complex evolutionary history in the Tianshan orogenic belt.It is a typical continental oil and gas bearing basin of coal derived hydrocarbon.Forming oil bearing sandbodies of pre Jurassic(Triassic) oil and gas accumulation in the southern belt of basin is obviously controlled by sedimentary facies,high geothermal gradient and Indo China movement.The pluvial delta sandbodies distributed in the southern basin are the first set of good oil bearing sandbodies because they lie on a suitable place near oil generation center due to strata uplifting in Indo China movement,and had a dynamic foundation of producing secondary porosity as well as trapping early mature oil which heated by magma bodies and Indo China structural heat event.The second,third, fourth set of oil bearing sandbodies of Jurassic in this area are the braided deltas with south terrigenous sediments and pluvial deltas with north terrigenous sedinents,and they have the characteristics of multiple layers of sandbodies,strongly repeated in the upper and lower part ,with fairly good original physical quality.They depend on coal measure source rocks and hydrocarbon migrated southwards in short distance.