【摘要】 松辽盆地古龙向斜葡萄花油层发育大面积连片的滞留油藏,利用测井、岩心、地震和室内分析化验等资料对其进行解剖研究,提出了古龙向斜葡萄花油层油气滞留成藏模式:嫩江组末期油气初始成藏期,青山口组源岩生成少量油沿着高孔渗砂体向凹陷周边放射状运移;明水组末期油气关键成藏期,青山口组源岩生成大量油受储层部分致密影响少部分滞留在向斜区成藏;依安组末期油气最终成藏期,青山口组源岩生成少量油气在储层完全致密和充足源储压差作用下在向斜区滞留成藏,认为滞留油藏具有埋藏深、岩性细、物性差、储层异常高压、油水空间倒置、连片式分布和甜点式富集的岩性油藏特征.研究结果表明:其形成的4种成因机制为:1)三角洲前缘亚相物源交汇区搬运距离远、粒度小(0.06<Md<0.16)、泥质含量高(泥地比>80%)、孔喉比大(>50)和储层非均质性强;2)同沉积构造抬升形成的地层厚度陡变带控制沉积中心造成颗粒分异差、压实强、岩屑-杂基塑性变形堵塞原始孔隙,同时继承性沉降中心和构造改造弱;3)成岩作用强(中成岩A2亚期)、溶蚀原生粒间孔隙为主(>70%)、石英含量低(21.66%)且次生加大、方解石充填、油层顶底泥岩排酸弱;4)油气成藏早期储层未致密成藏中期储层同步致密成藏晚期储层已经致密的3期成藏与储层物性演化史时空耦合关系有利于油气滞留.更多还原

【Abstract】 Large area of contiguous retention reservoirs are found in Putaohua reservoir of Gulong syncline,Songliao basin.Based on the logging data,core data,seismic data and laboratory analysis,hydrocarbon retention accumulation model of Putaohua reservoir in Gulong syncline was proposed here.At the end of Nenjiang formation,which is the initial hydrocarbon accumulation period,source rock of Qingshankou formation expelled a small amount of oil,which radially migrated to the regions surrounding the depression along the sand body with high porosity and permeability.At the end of Ming-shui formation,which is the key hydrocarbon accumulation period,source rock of Qingshankou formation expelled a large amount of oil,a small amount of which was stuck in syncline due to the effect of partially densified reservoir.At the end of Yi’an Formation,the final accumulation period,source rock of Qingshankou Formation expelled a small amount of oil and gas,which was stuck in syncline,and then,under the condition of fully densified reservoir and the action of sufficient pressure difference between source rocks and reservoir,the hydrocarbon retention reservoirs in syncline occurred.It is presented that the retention reservoirs possess the characteristics of lithologic reservoirs,such as deep burial depth,fine lithology,poor physical property,reservoir abnormal high pressure,oil-water inversion,contiguous distribution and "dessert" enrichment.Based on the above study,four main formation mechanisms of retention reservoirs are summarized here:1)the intersection regions of deltafront facies provenance charactered with long transportation distance,small particle size(0.06<Md<0.16),high mudstone content(the ratio of mudstone thickness to formation thickness exceeds 80%),high pore-throat ratio(exceeding 50)and strong reservoir heterogeneity;2)the abrupt change belt of stratigraphic thickness caused by codeposition tectonic uplifting controls the depocenter,which causes poor particle differentiation,strong compaction,and original porosity blocking due to plasticity deformation of detritus-matrix.Besides,the abrupt change belt inherits the subsidence center and weak tectonic reformation;3)the formation mechanism with the strong diagenesis(A2subfacies of middle diagenetic),mainly dissolved primary intergranular pores(accounting for over 70%),low quartz content(21.66%)with secondary enlargement,calcite filling,and mudstone located at the top and bottom of reservoir with poor acid discharge;4)the coupling relationships among the above three hydrocarbon accumulation periods(including early non-densified reservoir,middle synchronously densified reservoir and advanced fully densified)and reservoir physical property evolution are favorable for hydrocarbon retention.更多还原