Determining the process of densification and tectonic evolution of tight sandstone can help to understand the distribution of reservoirs and find relatively high-permeability areas.Based on integrated approaches of th...Determining the process of densification and tectonic evolution of tight sandstone can help to understand the distribution of reservoirs and find relatively high-permeability areas.Based on integrated approaches of thin section,scanning electron microscopy(SEM),cathode luminescence(CL),nuclear magnetic resonance(NMR),X-ray diffraction(XRD),N2 porosity and permeability,micro-resistivity imaging log(MIL)and three-dimensional seismic data analysis,this work discussed the reservoir characteristics of the member 8 of the Permian Xiashihezi Formation(He 8 sandstones)in the Linxing area of eastern Ordos Basin,determined the factors affecting reservoir quality,and revealed the formation mechanism of relatively high-permeability areas.The results show that the He 8 sandstones in the Linxing area are mainly composed of feldspathic litharenites,and are typical tight sandstones(with porosity<10%and permeability<1 mD accounting for 80.3%of the total samples).Rapid burial is the main reason for reservoir densification,which resulted in 61%loss of the primary porosity.In this process,quartz protected the original porosity by resisting compaction.The cementation(including carbonate,clay mineral and siliceous cementation)further densified the sandstone reservoirs,reducing the primary porosity with an average value of 28%.The calcite formed in the eodiagenesis occupied intergranular pores and affected the formation of the secondary pores by preventing the later fluid intrusion,and the Fe-calcite formed in the mesodiagenetic stage densified the sandstones further by filling the residual intergranular pores.The clay minerals show negative effects on reservoir quality,however,the chlorite coatings protected the original porosity by preventing the overgrowth of quartz.The dissolution of feldspars provides extensive intergranular pores which constitute the main pore type,and improves the reservoir quality.The tectonic movements play an important role in improving the reservoir quality.The current tectonic traces of the study area are mainly controlled by the Himalayan movement,and the high-permeability reservoirs are mainly distributed in the anticline areas.Additionally,the improvement degree(by tectonic movements)of reservoir quality is partly controlled by the original composition of the sandstones.Thus,the selection of potential tight gas well locations in the study area should be focused on the anticline areas with relatively good original reservoir quality.And the phenomena can be referenced for other fluvial tight sandstone basins worldwide.展开更多
The Upper Shihezi sedimentary rocks in the Linxing region has been estimated with a significant volume of tight sandstone gas.However,lateral distribution of the present-day stress magnitude is poorly understood,which...The Upper Shihezi sedimentary rocks in the Linxing region has been estimated with a significant volume of tight sandstone gas.However,lateral distribution of the present-day stress magnitude is poorly understood,which limits further gas production.Hence,a one-dimensional mechanical earth model and a three-dimensional heterogeneous geomechanical model are built to address this issue.The results indicate that the strike-slip stress regime is dominant in the Upper Shihezi Formation.Relatively low stresses are mainly located around wells L-60,L-22,L-40,L-90,etc,and stress distributions exhibit the similarity in the Members H2 and H4.The differential stresses are relatively low in the Upper Shihezi Formation,suggesting that complex hydraulic fracture networks may be produced.Natural fractures in the Upper Shihezi Formation contribute little to the overall gas production in the Linxing region.In addition,the minimum principal stress gradient increases with Young's modulus,suggesting that the stiffer rocks commonly convey higher stress magnitudes.There is a strong interplay between stress distribution and heterogeneity in rock mechanics.Overall,the relative error between the predicted and measured results is less than 10%,implying that the predicted stress distribution is reliable and can be used for subsequent analysis in the Linxing region.展开更多
Tight sandstone gas reservoirs have poorer porosityepermeability relationships,so conventional reservoir classification schemes can hardly satisfy the classification and evaluation demand of this type of reservoirs.To...Tight sandstone gas reservoirs have poorer porosityepermeability relationships,so conventional reservoir classification schemes can hardly satisfy the classification and evaluation demand of this type of reservoirs.To solve this problem,this paper took the Permian tight sandstone gas reservoir in the Linxing Block along the eastern margin of the Ordos Basin as an example to describe the micro-structures of the tight sandstone reservoirs by means of high-pressure mercury injection,nuclear magnetic resonance(NMR),scanning electron mi-croscope(SEM)and so on.Then,the control effect of micro-structure parameters on the macrophysical properties was studied.Finally,classification and evaluation of tight sandstone reservoirs were carried out on this basis.And the following research results were obtained.First,NMR can identify the distribution of pores of different sizes,and high-pressure mercury injection can reflect the poreethroat configuration and percolation capacity of a reservoir.Second,both methods are better coincident in the description results.With an in-crease of the right peak of T2 spectra,the mercury intrusion curve presents a concave shape and the pore throat radius increases while the pore type gradually changes from intragranular dissolution pores and intercrystalline pores to intergranular pores and intergranular disso-lution pores and the reservoir quality gets better.Third,micro-pore structure controls reservoir physical properties andfluid mobility.And the porosity of large pores is best correlated with the effective porosity,so it can be used to evaluate the reservoir capacity of tight sandstone.Fourth,the throat radius R15 obtained by high pressure mercury injection is in the best correlation with porosity and permeability,so it can be used to evaluate the percolation capacity of tight sandstone.Fifth,by combining the porosity of large pores with the R15,the tight sandstone reservoirs in the Linxing Block are classified into 4 categories,and the classification results are in a good agreement with the on-site well test data.It is concluded that the combination of high-pressure mercury injection and NMR can effectively identify the key parameters which reflect the reservoir capacity and percolation capacity of tight sandstone,and improve the reliability and integrity of reservoir classification.And by selecting the key parameters that reflect reservoir capacity and percolation capacity,it can provide guidance for the classification and evaluation of tight sandstone reservoirs.展开更多
A network structure of coalmine integrated automation system based on NetLinx was proposed. The features of three-layer-network structure were discussed in detail. The mechanism of time determination of the network wa...A network structure of coalmine integrated automation system based on NetLinx was proposed. The features of three-layer-network structure were discussed in detail. The mechanism of time determination of the network was analyzed. A design example of the integrated automation system for a real coalmine was presented.展开更多
基金financially supported by the National Science and Technology Major Project of China (grant No. 2016ZX05066001–002)the National Science Foundation for Young Scientists of China (grant No. 41702171)the Program for Excellent Talents in Beijing (grant No. 2017000020124G107)
文摘Determining the process of densification and tectonic evolution of tight sandstone can help to understand the distribution of reservoirs and find relatively high-permeability areas.Based on integrated approaches of thin section,scanning electron microscopy(SEM),cathode luminescence(CL),nuclear magnetic resonance(NMR),X-ray diffraction(XRD),N2 porosity and permeability,micro-resistivity imaging log(MIL)and three-dimensional seismic data analysis,this work discussed the reservoir characteristics of the member 8 of the Permian Xiashihezi Formation(He 8 sandstones)in the Linxing area of eastern Ordos Basin,determined the factors affecting reservoir quality,and revealed the formation mechanism of relatively high-permeability areas.The results show that the He 8 sandstones in the Linxing area are mainly composed of feldspathic litharenites,and are typical tight sandstones(with porosity<10%and permeability<1 mD accounting for 80.3%of the total samples).Rapid burial is the main reason for reservoir densification,which resulted in 61%loss of the primary porosity.In this process,quartz protected the original porosity by resisting compaction.The cementation(including carbonate,clay mineral and siliceous cementation)further densified the sandstone reservoirs,reducing the primary porosity with an average value of 28%.The calcite formed in the eodiagenesis occupied intergranular pores and affected the formation of the secondary pores by preventing the later fluid intrusion,and the Fe-calcite formed in the mesodiagenetic stage densified the sandstones further by filling the residual intergranular pores.The clay minerals show negative effects on reservoir quality,however,the chlorite coatings protected the original porosity by preventing the overgrowth of quartz.The dissolution of feldspars provides extensive intergranular pores which constitute the main pore type,and improves the reservoir quality.The tectonic movements play an important role in improving the reservoir quality.The current tectonic traces of the study area are mainly controlled by the Himalayan movement,and the high-permeability reservoirs are mainly distributed in the anticline areas.Additionally,the improvement degree(by tectonic movements)of reservoir quality is partly controlled by the original composition of the sandstones.Thus,the selection of potential tight gas well locations in the study area should be focused on the anticline areas with relatively good original reservoir quality.And the phenomena can be referenced for other fluvial tight sandstone basins worldwide.
基金The authors would like to thank the financial support from the National Natural Science Foundation of China(41702130,41872171 and 41672146)National Science and Technology Major Project(2016ZX05066)Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘The Upper Shihezi sedimentary rocks in the Linxing region has been estimated with a significant volume of tight sandstone gas.However,lateral distribution of the present-day stress magnitude is poorly understood,which limits further gas production.Hence,a one-dimensional mechanical earth model and a three-dimensional heterogeneous geomechanical model are built to address this issue.The results indicate that the strike-slip stress regime is dominant in the Upper Shihezi Formation.Relatively low stresses are mainly located around wells L-60,L-22,L-40,L-90,etc,and stress distributions exhibit the similarity in the Members H2 and H4.The differential stresses are relatively low in the Upper Shihezi Formation,suggesting that complex hydraulic fracture networks may be produced.Natural fractures in the Upper Shihezi Formation contribute little to the overall gas production in the Linxing region.In addition,the minimum principal stress gradient increases with Young's modulus,suggesting that the stiffer rocks commonly convey higher stress magnitudes.There is a strong interplay between stress distribution and heterogeneity in rock mechanics.Overall,the relative error between the predicted and measured results is less than 10%,implying that the predicted stress distribution is reliable and can be used for subsequent analysis in the Linxing region.
基金supported by the National Natural Science Foundation of China"Full-borchole pore throat characterization and modeling of tight sandstone based on the combination of image method and fluid method"(No.41602141)"Mechanism and effects of imbibition and retention of fracturing fluid in in-situ shale gas reservoirs"(No.41972139)the Independent Innovation Foundation of Universities(No.18CX02069A).
文摘Tight sandstone gas reservoirs have poorer porosityepermeability relationships,so conventional reservoir classification schemes can hardly satisfy the classification and evaluation demand of this type of reservoirs.To solve this problem,this paper took the Permian tight sandstone gas reservoir in the Linxing Block along the eastern margin of the Ordos Basin as an example to describe the micro-structures of the tight sandstone reservoirs by means of high-pressure mercury injection,nuclear magnetic resonance(NMR),scanning electron mi-croscope(SEM)and so on.Then,the control effect of micro-structure parameters on the macrophysical properties was studied.Finally,classification and evaluation of tight sandstone reservoirs were carried out on this basis.And the following research results were obtained.First,NMR can identify the distribution of pores of different sizes,and high-pressure mercury injection can reflect the poreethroat configuration and percolation capacity of a reservoir.Second,both methods are better coincident in the description results.With an in-crease of the right peak of T2 spectra,the mercury intrusion curve presents a concave shape and the pore throat radius increases while the pore type gradually changes from intragranular dissolution pores and intercrystalline pores to intergranular pores and intergranular disso-lution pores and the reservoir quality gets better.Third,micro-pore structure controls reservoir physical properties andfluid mobility.And the porosity of large pores is best correlated with the effective porosity,so it can be used to evaluate the reservoir capacity of tight sandstone.Fourth,the throat radius R15 obtained by high pressure mercury injection is in the best correlation with porosity and permeability,so it can be used to evaluate the percolation capacity of tight sandstone.Fifth,by combining the porosity of large pores with the R15,the tight sandstone reservoirs in the Linxing Block are classified into 4 categories,and the classification results are in a good agreement with the on-site well test data.It is concluded that the combination of high-pressure mercury injection and NMR can effectively identify the key parameters which reflect the reservoir capacity and percolation capacity of tight sandstone,and improve the reliability and integrity of reservoir classification.And by selecting the key parameters that reflect reservoir capacity and percolation capacity,it can provide guidance for the classification and evaluation of tight sandstone reservoirs.
文摘A network structure of coalmine integrated automation system based on NetLinx was proposed. The features of three-layer-network structure were discussed in detail. The mechanism of time determination of the network was analyzed. A design example of the integrated automation system for a real coalmine was presented.
