板桥凹陷沙三段油气生成、运移和聚集数值模拟

Numerical Simulation of Petroleum Generation, Migration and Accumulation of the Es_3 Formation in Banqiao Depression

板桥凹陷主要烃源岩为沙三段地层暗色泥岩,而沙三段砂岩为板桥凹陷主要储层之一.在恢复板桥凹陷埋藏史、热史和成熟史的基础上,定量模拟沙三段油气生成、运移和聚集特征,模拟结果利用实测镜质体反射率(Ro)、地层温度和63口井钻探结果验证.模拟结果表明:(1)板桥凹陷现今的热流值在59.8～61.7mW/m2之间,古热流演化经历了早期(65～50.4Ma)持续升高和晚期(50.4～0Ma)逐渐降低两个阶段,在距今50.4Ma达到最高;(2)东营组沉积末期,板桥凹陷沙三段烃源岩成熟度(Ro)大约在0.5%～1.25%之间,现今成熟度(Ro)范围大约在0.5%～1.8%之间,在距今大约35Ma开始生烃,距今30Ma开始达到生烃高峰;(3)沙三段烃源岩在距今大约31Ma开始排烃,距今31～26Ma为主要排烃阶段,距今26～0Ma为少量排烃阶段;(4)板桥凹陷油气主要运移路径主要受控于古构造面,凹陷区以发散流为主,北部陡坡带以平行流为主,汇聚流主要存在板桥凹陷南部缓坡带.在板桥凹陷沙三段存在6个有利油气聚集区,其中以聚集区Ⅰ和Ⅱ最有利,主要是因为近源、油气运移动力强和运移距离短.

The mudstones of the Es3 formation in Banqiao depression are the dominant source rocks for the major hydrocarbon accumulations and the sandstones of Es3 formation are major reservoir rocks. Petroleum generation, migration and accumulation history of the Es3 formation in Banqiao depression are modelled based on reconstruction of the burial, thermal and maturity history in this paper. The Modelling results are calibrated with measured vitrinite reflectance （Ro）, borehole temperatures and drilling results of 63 wells. The modelling results indicate that： （1） the present-day heat flow in Banqiao depression varies from 59.8 to 61.7 mW/me and that the paleoheat flow increased from 65 to 50. 4 Ma, reaching peak heat flow values at 50. 4 Ma then decreased with from 50. 4 to 0 Ma; （2） the source rocks maturity of Es3 formation ranges from 0. 75% to 1.8% R, at present day and from 0. 5% to 1.25% Ro at the end of the Ed formation deposition （26 Ma）. Oil generation （0. 5% R,,） in Es： formation began from around 35 Ma and peak hydrocarbon generation （1.0% Ro） occured from 30 Ma; （3） the timing of hydrocarbon expulsion from Ess formation source rocks began from 31 Ma, the predominant phase of hydrocarbon expulsion is from 31 to 26 .Via and the phase of less hydrocarbon expulsion is from 26 to 0 Ma; （4） secondary petroleum migration pathways of Es3, formation of Banqiao depression at present and 26 Ma are controlled by the paleo-stmcture surface and the spreading flowing, confluence flowing and the planar flowing occur in depression zone, the gentle slope zone and the sleep slopc zone respectively. Six favorable zones of oil accumulations in the Es3 formation of Banqiao depression arc identified , especially the oil accumulations zone Ⅰ and Ⅱ, due to their location being close to the generative kitchens, short oil migration distance and powerful drive force.