Hydrocarbon retention mechanism and accumulation model of syncline area in depression:as Putaohua reservoir in Gulong syncline,Songliao basin
【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.
【Key words】 retention reservoir； formation mechanism； accumulation model； Putaohua reser-voir； Gulong syncline； Songliao basin；
- 【文献出处】 中国矿业大学学报 ,Journal of China University of Mining & Technology , 编辑部邮箱 ,2015年01期
- 【网络出版时间】2014-09-18 08:53