The Middle Permian Qixia Formation in the Shuangyushi area,northwestern Sichuan Basin,develops shoal-facies dolomite reservoirs.To pinpoint promising reservoirs in the Qixia Formation,deep thin shoal-facies dolomite r...The Middle Permian Qixia Formation in the Shuangyushi area,northwestern Sichuan Basin,develops shoal-facies dolomite reservoirs.To pinpoint promising reservoirs in the Qixia Formation,deep thin shoal-facies dolomite reservoirs were predicted using the techniques of pre-stack Kirchhoff-Q compensation for absorption,inverse Q filtering,low-to high-frequency compensation,forward modeling,and facies-controlled seismic meme inversion.The results are obtained in six aspects.First,the dolomite reservoirs mainly exist in the middle and lower parts of the second member of Qixia Formation(Qi2 Member),which coincide with the zones shoal cores are developed.Second,the forward modeling shows that the trough energy at the top and bottom of shoal core increases with increasing shoal-core thickness,and weak peak reflections are associated in the middle of shoal core.Third,five types of seismic waveform are identified through waveform analysis of seismic facies.Type-Ⅰ and Type-Ⅱ waveforms correspond to promising facies(shoal core microfacies).Fourth,vertically,two packages of thin dolomite reservoirs turn up in the sedimentary cycle of intraplatform shoal in the Qi2 Member,and the lower package is superior to the upper package in dolomite thickness,scale and lateral connectivity.Fifth,in plane,significantly controlled by sedimentary facies,dolomite reservoirs laterally distribute with consistent thickness in shoal cores at topographical highs and extend toward the break.Sixth,the promising prospects are the zones with thick dolomite reservoirs and superimposition of horstegraben structural traps.展开更多
Macroscopic and microscopic characteristics revealed that the Dengying Formation reservoir in the central Sichuan paleo-uplift belonged to the compound genetic reservoir of the mound-shoal facies and karst.Development...Macroscopic and microscopic characteristics revealed that the Dengying Formation reservoir in the central Sichuan paleo-uplift belonged to the compound genetic reservoir of the mound-shoal facies and karst.Development of the reservoir was controlled by the mound-shoal facies,and dissolution-enlarged or added pores(vugs)due to superimposed karstification modification were favorable reservoir spaces.The karst of the Dengying Formation in Tongwan stage was the stratabound-weathered crust karst of the early diagenesis stage,the extensive superimposition of mound-shoal facies and regional karstification in the central Sichuan paleo-uplift area was the key to develop the large-scale continuous Dengying Formation reservoirs.Due to differences in the development degree of mound-shoal facies and in the intensity of karst modification,the reservoir development degree varied in different zones in the paleouplift area.The NS-extending zone on the western side of the Gaoshiti-Moxi area was the sweet spot for reservoir development.Effective identification of mound-shoal facies and fine depiction of karst landform was the key for reservoir prediction of the Dengying Formation to discovery the superimposed area of the mound-shoal facies and the karst monadnock-karst steep slope which similar to Moxi-Gaoshiti area.展开更多
Based on seismic, drilling data and experimental analysis, the characteristics and main controlling factors of shoal dolomite gas reservoir in the third member of Ordovician Yingshan Formation of Gucheng area, Tarim b...Based on seismic, drilling data and experimental analysis, the characteristics and main controlling factors of shoal dolomite gas reservoir in the third member of Ordovician Yingshan Formation of Gucheng area, Tarim basin were examined.The study shows that the dolomite gas reservoir in Gucheng area is lithologic gas reservoir controlled by shoal and fault jointly,and its formation is mainly attributed to the following factors:(1) The continuously developing paleotectonic structure has been in the direction of gas migration and accumulation;(2) The large area of medium-high energy grain bank deposited in gentle slope environment is the material basis for the formation of dolomite reservoir;(3) Atmospheric water leaching and dolomitization and fluid dissolution in fault zone are the key factors for the formation of high-quality dolomite reservoir;(4)The natural gas comes from cracking of the ancient oil reservoir and hydrocarbon generation of dispersed organic matter in source rocks, and the NNE-trending strike-slip fault is the dominant channel for vertical migration of natural gas;(5) Limestone cap rocks in the first and second members of Yingshan Formation provide direct sealing for the formation of gas reservoir there. On the basis of comprehensive analysis, it is pointed out that the Gucheng area has three grain shoal zones in the third member of Yingshan Formation in nearly S-N direction, which together with seven strike-slip fault zones in NNE direction control the development of shoal dolomite gas reservoir.展开更多
文摘The Middle Permian Qixia Formation in the Shuangyushi area,northwestern Sichuan Basin,develops shoal-facies dolomite reservoirs.To pinpoint promising reservoirs in the Qixia Formation,deep thin shoal-facies dolomite reservoirs were predicted using the techniques of pre-stack Kirchhoff-Q compensation for absorption,inverse Q filtering,low-to high-frequency compensation,forward modeling,and facies-controlled seismic meme inversion.The results are obtained in six aspects.First,the dolomite reservoirs mainly exist in the middle and lower parts of the second member of Qixia Formation(Qi2 Member),which coincide with the zones shoal cores are developed.Second,the forward modeling shows that the trough energy at the top and bottom of shoal core increases with increasing shoal-core thickness,and weak peak reflections are associated in the middle of shoal core.Third,five types of seismic waveform are identified through waveform analysis of seismic facies.Type-Ⅰ and Type-Ⅱ waveforms correspond to promising facies(shoal core microfacies).Fourth,vertically,two packages of thin dolomite reservoirs turn up in the sedimentary cycle of intraplatform shoal in the Qi2 Member,and the lower package is superior to the upper package in dolomite thickness,scale and lateral connectivity.Fifth,in plane,significantly controlled by sedimentary facies,dolomite reservoirs laterally distribute with consistent thickness in shoal cores at topographical highs and extend toward the break.Sixth,the promising prospects are the zones with thick dolomite reservoirs and superimposition of horstegraben structural traps.
基金This work was funded by National Science and Technology Major Project of China(No.2011ZX05004-005)PetroChina Major Exploration Project(No.2012ZD01).
文摘Macroscopic and microscopic characteristics revealed that the Dengying Formation reservoir in the central Sichuan paleo-uplift belonged to the compound genetic reservoir of the mound-shoal facies and karst.Development of the reservoir was controlled by the mound-shoal facies,and dissolution-enlarged or added pores(vugs)due to superimposed karstification modification were favorable reservoir spaces.The karst of the Dengying Formation in Tongwan stage was the stratabound-weathered crust karst of the early diagenesis stage,the extensive superimposition of mound-shoal facies and regional karstification in the central Sichuan paleo-uplift area was the key to develop the large-scale continuous Dengying Formation reservoirs.Due to differences in the development degree of mound-shoal facies and in the intensity of karst modification,the reservoir development degree varied in different zones in the paleouplift area.The NS-extending zone on the western side of the Gaoshiti-Moxi area was the sweet spot for reservoir development.Effective identification of mound-shoal facies and fine depiction of karst landform was the key for reservoir prediction of the Dengying Formation to discovery the superimposed area of the mound-shoal facies and the karst monadnock-karst steep slope which similar to Moxi-Gaoshiti area.
基金Supported by the National Natural Science Foundation of China(Grant No.U20A201009 and 41972157)PetroChina Science and Technology Major Project(Grant No.2016E-0204)。
文摘Based on seismic, drilling data and experimental analysis, the characteristics and main controlling factors of shoal dolomite gas reservoir in the third member of Ordovician Yingshan Formation of Gucheng area, Tarim basin were examined.The study shows that the dolomite gas reservoir in Gucheng area is lithologic gas reservoir controlled by shoal and fault jointly,and its formation is mainly attributed to the following factors:(1) The continuously developing paleotectonic structure has been in the direction of gas migration and accumulation;(2) The large area of medium-high energy grain bank deposited in gentle slope environment is the material basis for the formation of dolomite reservoir;(3) Atmospheric water leaching and dolomitization and fluid dissolution in fault zone are the key factors for the formation of high-quality dolomite reservoir;(4)The natural gas comes from cracking of the ancient oil reservoir and hydrocarbon generation of dispersed organic matter in source rocks, and the NNE-trending strike-slip fault is the dominant channel for vertical migration of natural gas;(5) Limestone cap rocks in the first and second members of Yingshan Formation provide direct sealing for the formation of gas reservoir there. On the basis of comprehensive analysis, it is pointed out that the Gucheng area has three grain shoal zones in the third member of Yingshan Formation in nearly S-N direction, which together with seven strike-slip fault zones in NNE direction control the development of shoal dolomite gas reservoir.
