There are few reports about the penecontemporaneous karst of the lacustrine carbonate of Da'anzhai Member which developed on the top of Lower Jurassic Ziliujing Formation,eastern Sichuan Basin.Based on the analysi...There are few reports about the penecontemporaneous karst of the lacustrine carbonate of Da'anzhai Member which developed on the top of Lower Jurassic Ziliujing Formation,eastern Sichuan Basin.Based on the analysis of the macroscopic and microscopic characteristics of Heping Reservoir section in Beibei area,It is discovered that the penecontemporaneous karst in the lacustrine carbonate,Da'anzhai Member,and its characters as follows:(1)The dissolved fractures and karrens are common,which have been filled with vadose silts,bioclasts,terrigenous quartzes,crystal and intergrown calcites;(2)The penecontemporaneous karstification mainly occurs in the micrites and shell limestones of the middle and upper part of the shallowing-upward sequence,and the desiccation cracks occur in some shallowing-upward sequences;(3)Three meteoric-water diagenetic lenses are identified in this section.By further study we also find the factures,stylolite and burial dissolution pores occur along the karst system(tubes,conduits and caves of the karst).And the asphalt not only fills the stylolites and fractures,but also is mixed with the vadose silt in the karst system,although the pore space formed by penecontemporaneous karstification is filled with vadose material and cements.Therefore it is concluded that the development and modification of the tight lacustrine carbonate reservoir of Da'anzhai Member,to some extent,are relevant with the penecontemporaneous karstification,and the penecontemporaneous karst reservoir may develop in the buried Da'anzhai carbonate of the basin.展开更多
This paper focuses on the Longwangmiao gas reservoir in Moxi-Gaoshiti area,Sichuan Basin.Starting from the tectonic evolution perspective,though comparing biological marker compound and analyzing fluid inclusions,the ...This paper focuses on the Longwangmiao gas reservoir in Moxi-Gaoshiti area,Sichuan Basin.Starting from the tectonic evolution perspective,though comparing biological marker compound and analyzing fluid inclusions,the oil&gas origin and accumulation evolution of Longwangmiao Formation are systematic studied with reference to the burial-thermal evolution of single well geological history in the study area.It is suggested that the oil&gas reservoir is generally characterized by early accumulation,multi-stage filling,late cracking and later adjustment.The oil and gas were mainly sourced from lower Cambrian Qiongzhusi Formation,partly from the Permian source rock.During the geological period,3 major oil&gas fillings occurred in the Longwangmiao Formation,namely Caledonian-Hercynian filling that was small in scale and produced the first phase of paleo-oil reservoir that soon destroyed by Caledonian movement uplift,large-scale Permian filling that gave rise to the second-phase of paleo-oil reservoir and the Triassic-Jurassic filling that enriched the second phase of paleo-oil reservoir.Finally,the paleo-oil reservoir experienced an in-situ cracking during the cretaceous period that gave rise to a natural gas reservoir and left behind carbonaceous bitumen and oily bitumen in the holes of the Longwangmiao Formation.展开更多
基金This study was supported by Unconventional Oil&Gas,Scientific Research Innovation Team Building Project,Universities Affiliated to Sichuan Province(Provincial Teaching Designed 127 Education Office of Sichuan Province).
文摘There are few reports about the penecontemporaneous karst of the lacustrine carbonate of Da'anzhai Member which developed on the top of Lower Jurassic Ziliujing Formation,eastern Sichuan Basin.Based on the analysis of the macroscopic and microscopic characteristics of Heping Reservoir section in Beibei area,It is discovered that the penecontemporaneous karst in the lacustrine carbonate,Da'anzhai Member,and its characters as follows:(1)The dissolved fractures and karrens are common,which have been filled with vadose silts,bioclasts,terrigenous quartzes,crystal and intergrown calcites;(2)The penecontemporaneous karstification mainly occurs in the micrites and shell limestones of the middle and upper part of the shallowing-upward sequence,and the desiccation cracks occur in some shallowing-upward sequences;(3)Three meteoric-water diagenetic lenses are identified in this section.By further study we also find the factures,stylolite and burial dissolution pores occur along the karst system(tubes,conduits and caves of the karst).And the asphalt not only fills the stylolites and fractures,but also is mixed with the vadose silt in the karst system,although the pore space formed by penecontemporaneous karstification is filled with vadose material and cements.Therefore it is concluded that the development and modification of the tight lacustrine carbonate reservoir of Da'anzhai Member,to some extent,are relevant with the penecontemporaneous karstification,and the penecontemporaneous karst reservoir may develop in the buried Da'anzhai carbonate of the basin.
基金Supported by the National Science and Technology Major Project of China(2011ZX05004-005-03).
文摘This paper focuses on the Longwangmiao gas reservoir in Moxi-Gaoshiti area,Sichuan Basin.Starting from the tectonic evolution perspective,though comparing biological marker compound and analyzing fluid inclusions,the oil&gas origin and accumulation evolution of Longwangmiao Formation are systematic studied with reference to the burial-thermal evolution of single well geological history in the study area.It is suggested that the oil&gas reservoir is generally characterized by early accumulation,multi-stage filling,late cracking and later adjustment.The oil and gas were mainly sourced from lower Cambrian Qiongzhusi Formation,partly from the Permian source rock.During the geological period,3 major oil&gas fillings occurred in the Longwangmiao Formation,namely Caledonian-Hercynian filling that was small in scale and produced the first phase of paleo-oil reservoir that soon destroyed by Caledonian movement uplift,large-scale Permian filling that gave rise to the second-phase of paleo-oil reservoir and the Triassic-Jurassic filling that enriched the second phase of paleo-oil reservoir.Finally,the paleo-oil reservoir experienced an in-situ cracking during the cretaceous period that gave rise to a natural gas reservoir and left behind carbonaceous bitumen and oily bitumen in the holes of the Longwangmiao Formation.
