Using the fractal geometry method,the microscopic pore structures of tight sandstone reservoirs in Kalpintag Formation of Shuntuoguole area in Tarim Basin were conducted fractal characterization on the base of test an...Using the fractal geometry method,the microscopic pore structures of tight sandstone reservoirs in Kalpintag Formation of Shuntuoguole area in Tarim Basin were conducted fractal characterization on the base of test analysis data such as physical property,cast thin section,scanning electron microscope and mercury injection,and the genetic mechanism of pore structure heterogeneity was investigated.The storage spaces are dominated by intergranular dissolved pore,intragranular dissolved pore and residual intergranular pore,and the throat type consists of the necking throat,lamellar throat,curved lamellar throat and tube-shaped throat.The microscopic structure type includes Type Ⅰ(fractal dimension≤2.350),Type Ⅱ(2.350<fractal dimension<2.580),Type Ⅲ(fractal dimension>2.580)and fracture type.The most favorable reservoirs with Type-Ⅰ microscopic pore structure are mainly distributed in the Upper Member of Kalpintag Formation,while the reservoirs with Type-Ⅱ and Type-Ⅲ microscopic pore structures are mainly in the Lower Member of Kalpintag Formation.The sedimentation controls the heterogeneity of microscopic pore structure,and the differences on composition and particle size of sandstone lead to differentiation of microscopic pore structures.The Lower Member of the Kalpintag Formation experiences stronger compaction and cementation but weaker dissolution than the Upper Member of the Kalpingtag Formation,and thus the microscopic pore structure of Upper Member of the Kalpintag Formation is significantly worse that of the Lower Member o the Kalpingtag Formation.The Upper Member of the Kalpintag Formation with high content of brittle mineral develops microscopic fractures due to tectonic rupture,thus the permeability is improved and the heterogeneity of microscopic pore structures is enhanced;but the Lower Member of Kalpintag Formation is characterized by attrition crushing of particles and strong compaction.展开更多
The Chang 6 reservoir of Yanchang formation in Jingan oilfield has relatively poor quality:the porosity ranges mainly from 8 to 14%,and permeability ranges from 0.018 to 10.48 md,with a mean of 1.10 md,categorized as ...The Chang 6 reservoir of Yanchang formation in Jingan oilfield has relatively poor quality:the porosity ranges mainly from 8 to 14%,and permeability ranges from 0.018 to 10.48 md,with a mean of 1.10 md,categorized as low porosity and low permeability reservoir type with strong heterogeneity.Petrographic and geochemical analyses of various components in these sandstones have provided clues of diagenesis.The sandstones at the early stage of diagenesis are characterized by non-ferroan calcite cementation,grain-coating,pore-lining clay minerals,and initial dissolution of detrital grains.Authigenic quartz,porefilling and grain-replacive laumontites,albitized detrital plagioclase,authigenic K-feldspar,illite and late ferroan calcite cement dominate the late diagenesis.Reservoir quality is influenced by products of late diagenesis stage,the cement(calcite,albite,quartz,illite,and laumontite)occluded primary and secondary porosity.The organic acidic fluid derived from organic matter in the source rocks during the late diagenesis,which results in the dissolution of detrital plagioclase and laumontite cement and was the main reason for the enhancement of reservoir-quality.As a result of that,the residual primary pore and dissolution pore comprised the main accumulation space for oil and gas,and thus become important targets for hydrocarbon exploration.展开更多
基金supported by the National Science and Technology Major Project of China(No.2011ZX05002-003).
文摘Using the fractal geometry method,the microscopic pore structures of tight sandstone reservoirs in Kalpintag Formation of Shuntuoguole area in Tarim Basin were conducted fractal characterization on the base of test analysis data such as physical property,cast thin section,scanning electron microscope and mercury injection,and the genetic mechanism of pore structure heterogeneity was investigated.The storage spaces are dominated by intergranular dissolved pore,intragranular dissolved pore and residual intergranular pore,and the throat type consists of the necking throat,lamellar throat,curved lamellar throat and tube-shaped throat.The microscopic structure type includes Type Ⅰ(fractal dimension≤2.350),Type Ⅱ(2.350<fractal dimension<2.580),Type Ⅲ(fractal dimension>2.580)and fracture type.The most favorable reservoirs with Type-Ⅰ microscopic pore structure are mainly distributed in the Upper Member of Kalpintag Formation,while the reservoirs with Type-Ⅱ and Type-Ⅲ microscopic pore structures are mainly in the Lower Member of Kalpintag Formation.The sedimentation controls the heterogeneity of microscopic pore structure,and the differences on composition and particle size of sandstone lead to differentiation of microscopic pore structures.The Lower Member of the Kalpintag Formation experiences stronger compaction and cementation but weaker dissolution than the Upper Member of the Kalpingtag Formation,and thus the microscopic pore structure of Upper Member of the Kalpintag Formation is significantly worse that of the Lower Member o the Kalpingtag Formation.The Upper Member of the Kalpintag Formation with high content of brittle mineral develops microscopic fractures due to tectonic rupture,thus the permeability is improved and the heterogeneity of microscopic pore structures is enhanced;but the Lower Member of Kalpintag Formation is characterized by attrition crushing of particles and strong compaction.
基金The work was supported by China National Petroleum Company(2010D-5006-0103)funded by State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation(PLN201616)Key Laboratory of Tectonics and Petroleum Resources of Ministry of Education(TPR-2013-16).We are grateful to the Core analysis Unit at the Chengdu Institute of Sedimentology and Mineralogy.We thank the Stable Isotope Unit at the Central Laboratory of Changqing Oilfield.We thank Zhao Jingzhe,the director of exploration and development,Liu Lili andWei Liping,for assistance with collecting materials and valuable discussions,and Zheng Guanghui for assistance with our field work.The manuscript also benefited from suggestions by Wang Qi,a research scientist at Lanzhou Institute of Geology.
文摘The Chang 6 reservoir of Yanchang formation in Jingan oilfield has relatively poor quality:the porosity ranges mainly from 8 to 14%,and permeability ranges from 0.018 to 10.48 md,with a mean of 1.10 md,categorized as low porosity and low permeability reservoir type with strong heterogeneity.Petrographic and geochemical analyses of various components in these sandstones have provided clues of diagenesis.The sandstones at the early stage of diagenesis are characterized by non-ferroan calcite cementation,grain-coating,pore-lining clay minerals,and initial dissolution of detrital grains.Authigenic quartz,porefilling and grain-replacive laumontites,albitized detrital plagioclase,authigenic K-feldspar,illite and late ferroan calcite cement dominate the late diagenesis.Reservoir quality is influenced by products of late diagenesis stage,the cement(calcite,albite,quartz,illite,and laumontite)occluded primary and secondary porosity.The organic acidic fluid derived from organic matter in the source rocks during the late diagenesis,which results in the dissolution of detrital plagioclase and laumontite cement and was the main reason for the enhancement of reservoir-quality.As a result of that,the residual primary pore and dissolution pore comprised the main accumulation space for oil and gas,and thus become important targets for hydrocarbon exploration.
