断层幕式活动期和间歇期流体运移与油气成藏特征

FEATURES OF FLUID MIGRATION AND HYDROCARBON ACCUMULATION IN THE ACTIVE AND INTERMITTENT STAGES OF FAULT EPISODIC ACTIVITIES

断层的周期性幕式活动导致沿断层带流体运移具有周期性幕式运动的特点。断层的一次周期性幕式活动分为活动期和间歇期两个阶段。断层幕式活动期,深部流体在超压作用或地震泵作用下以在断层带内的垂向运移和进入储层后的侧向运移为主,流体运移的相态为油、气、水的混合相态。断层幕式活动间歇期,当断层带尚未完全封闭、输导系统内压力尚未平衡时,流体在断层带及其两侧储层之间流动,直至达到压力平衡。断层完全封闭后,流体运移则不再发生。断层幕式活动期对油气的输导能力强,而断层幕式活动间歇期对油气的输导能力相对较弱。断层幕式活动期导致断层带附近形成同层混源或异层同源的多层系(或多构造层)含油气复式油气聚集带;而断层幕式活动间歇期使已经形成的油气藏发生再分配,导致断层带垂向上形成欠饱和油藏—高饱和油气藏—油气藏及纯气藏的完整序列。

Periodical episodic activities of faults lead to the periodical episodic movement of fluid migration along fault zones. One episodic activity of a fault consists of two stages: the active stage and the intermittent stage. During the active stage, fluid in deep formation migrates vertically along fault zones and then flows laterally in reservoirs under the power of superpressure or seismic pump, and the fluid migrates in the mixed phase states of oil, gas and water. In the intermittent stage, when fault zones are still open and pressure in leading systems has not got to balance, fluid flows adjustively in fault zones and bilateral reservoirs until the pressure is balanced. When faults close completely, fluid flow ceases. So the transport ability of fault zones is strong in the active stage but weak in the intermittent stage. In the episodic active stage, complex hydrocarbon-accumulating zones with multiple oil-bearing measures, which contain the same formation with different oil sources or different formations with the same oil source, will form adjacent to fault zones. In the episodic intermittent stage, the redistributed oil and gas pools in leading systems lead to the intact vertical series of undersaturated oil pools, high-saturated oil pools, oil and gas pools and pure gas pools around fault zones.