Study Of Petroleum Systems And Controlling Factors In Beier Depression

Based on the comprehensive utilization of electricity, lithologic and logging data, paleontological data and seismic reflection characteristics, based on stratigraphic framework dentified 10 main sectors in the middle of Hai ta basin. Divided out 3 types of basin in vertical, from bottom to up are follows:residual basin among mountains from sector 1-sector3;passive rift basin from sector 3 to sector5;active rift basin uper of sector5. Active rift basin which can be further divided into 3 major tectonic layer, that is, from sector5 to sector 7 constitute the rift structure layer; from sector7 to reflectionT04 constitute rift to depression structure layer; from T04 to shallow formed depression structuer Layer.by analyzing the fracture orientation, size, nature, space combination of style, primary, and secondary relationship between faults, studied faults combination model of Beier depression.By use of structural features of sequence boundaries, fracture growth index, and structural balance activity rate,analysis the deformation period of main boundary fault, with fault geometry characteristics, structural styles fault systemto were divided,analyze the deformation period of faults and the controlisim of hydrocarbon accumulationBasis of sedimentary filling characteristics and structure evolution of different periods in Beier depression, system analyzes the coupling between structure and sedimentary, that structural and sedimentary "Coupling"control the formation of different combination of reservoir. Passive rift faults weak active screen form a "pan-pot", with tilting deformation or low uplift, high-quality"source rock "climbing on the "high quality reservoir", forming a uper born lower reservoir combination mode; in active rift eatly period, faults active strongly form a "wedge-shaped sedimentary body", high-quality reservoir "tongue" in depth "source rocks", forming a self born self reservoir combination mode. Straun rapid suvsidence during rift to depression period, later rebersal faults adjustment hydrocarbon formed lower born upper reservoir combination mode.By study of critical moment of oil and gas accumulation,three sets of petroleum systerms were divided in Beier depression, they are:passive rift primary petroleum system; active rift primary petroleum systemand rift to depression secondary petroleum system.Through the typical oil reservoir distribution and reservoir anatomical results indicate that most of oil concentrated in passive rift petroleum system,,developing reverse fault seal reservoir and unconformity -fault block of the buried hill reservoir. Active rift petroleum systerm developed structure and fault-lithologic reservoir; secondary petroleum systerm mainlu developed fault-lithologic reservoir rock;secondary petroleum and native petroleum "complementary" distribution. Through the study of oil and gas distribution, indicate that (1) special lithologic sourcerock control oil and gas distribution of lower systems; T5 reflector buried hill indicates oil and gas distribution of lower systems; reverse faults back of low rift control oil and gas distribution of lower systems.(2) Nan yi sourcerock control oil and gas distribution of middle systems;T22 reflector Paleouplift inherited, Tilteduplift indicates oil and gas distribution of middle systems;reverse fault-fan in convert part of depression control oil and gas accumulation of middle sustems. (3) "faults-cover" combined feature control the oil and gas distribution of upper systems;T04 reflector inversion structure indicate oil and gas distribution of upper system; reverse fault-part control oil and gas distribution of upper system.By comprehensive study of source conditions, combination of reservoir, migration approach, and petroleum accumulation period and structer evolution, that petroleum short lateral migration within source "orientation" accumulation, specific performance are:(1) buried hill same faults transporting revers faults block side born side reservoir accumulation mode; (2) fault segment unconformity on rift area in depression accumulation mode;(3) reverse fault back against low uplift hydrocarbon accumulation mode;(4)fan body on conversion area hydrocarbon accumulation mode;(5)reverse faults control secondary oil and gas accumulation mode.