This paper analyzed the water-retention mechanism of feldspathic sandstone （fine-（〈 1 mm diam.） and gravel-sized （2-3 cm diam.） in Mu Us Sandy Land, Northwest China. The objective of this study is to study the e...This paper analyzed the water-retention mechanism of feldspathic sandstone （fine-（〈 1 mm diam.） and gravel-sized （2-3 cm diam.） in Mu Us Sandy Land, Northwest China. The objective of this study is to study the effect of feldspathic sandstone amendment on water retention in sandy land. The results showed that as the proportion of fine feldspathic sandstone in the sandy land soil increased, the soil texture changed from sand to silt loam, the capillary po- rosity gradually increased from 26.3% to 44.9%, and the soil saturated hydraulic conductivity decreased from 7.10 ram/rain to 0.07 mm/min. Feldspathic sandstone gravel formed micro-reservoirs in the sandy land soil, playing the role of a ＇water absorbent＇ and ＇water retaining agent＇ in sandy land. Amendment with feldspathic sandstone can increase water retention in the arable layer of sandy land by 67%. This study provides a theoretical basis for the amelioration of sandy land on a large scale. It can be concluded that amendment with feldspathic sandstone can improve the physical properties of sandy land soil and increase soil water retention.展开更多
Petrographic analysis combined with various techniques, such as scanning electron microscopy and X-ray diffraction, was used to assess the timing of growth and original mineral cements, the controls on reservoir and r...Petrographic analysis combined with various techniques, such as scanning electron microscopy and X-ray diffraction, was used to assess the timing of growth and original mineral cements, the controls on reservoir and reservoir quality of the fourth member sandstones of Shahejie formation (Es4). The Es4 sandstones are mostly arkose and lithic arkose, rarely feldspathic litharenite, with an average mass fraction of quartz 51.6%, feldspar 33.8% and rock fragments 14.6% (Q51.6F33.8R14.6). They have an average framework composition (mass fraction) of quartz 57.10%, K-feldspar 5.76%, sodium-calcium feldspar 13.00%, calcite 5.77%, dolomite 5.63%, siderite 0.95%, pyrite 0.30%, anhydrite 0.04%, and clay mineral 11.46%. The diagenentic minerals typically include kaolinite, illite-smectite (I/S), illite, chlorite, authigenetic quartz and feldspar, and carbonate and pyrite. Es4 sandstone has undergone stages A and B of eodiagenesis, and now, it is experiencing stage A of mesodiagenesis. Reservoir quality is predominantly controlled by the mechanical compaction, for example, 45.65% of the original porosity loss is related to compaction. The original porosity loss related with cementation is only 26.00%. The reservoir quality is improved as a result of dissolution of feldspar, rock fragment and so forth. The porosity evolved from dissolution varies from 3% to 4%.展开更多
In order to understand the diagenesis and its influence on porosity and permeability of sandstones from Yingcheng Formation in Jinshan field,applying thin sections,casting and scanning electron microscope,the authors ...In order to understand the diagenesis and its influence on porosity and permeability of sandstones from Yingcheng Formation in Jinshan field,applying thin sections,casting and scanning electron microscope,the authors studied petrography,diagenesis,porosity and permeability of Yingcheng Formation sandstone reservoir. The results show that the reservoir of Yingcheng Formation is mainly composed of lithic arkoses. Sandstones experienced compaction,pressolution,cementation,metasomatism and dissolution. The primary pores of the sandstones are undeveloped; most of pores are the secondary pores,which are mainly intragranular dissolution pores in feldspar and debris. The compaction and cementation reduced the primary pores in sandstones,the porosity and permeability decreased; while the dissolution formed the secondary pores,resulting in the porosity and permeability increase. Due to compaction and cementation,the porosity and permeability are reduced with increasing of depth. There exists an abnormal enlargement of porosity and permeability within a depth range 2310--2450 m. In combination with analysis of petrology,the dissolution of feldspar and debris is most developed in the depth range. Therefore,compaction,cementation and dissolution are the important factors which affect the porosity and permeability of sandstones.展开更多
基金Under the auspices of Key Direction Program of Chinese Academy of Science(No.KZCX2-YW-Q06-03)MajorState Basic Research Development Program of China(No.2009CB421103)+1 种基金National Natural Science Foundation of China(No.41001050)Major Science and Technology Program for Water Pollution Control and Treatment(No.2012ZX07201004)
文摘This paper analyzed the water-retention mechanism of feldspathic sandstone （fine-（〈 1 mm diam.） and gravel-sized （2-3 cm diam.） in Mu Us Sandy Land, Northwest China. The objective of this study is to study the effect of feldspathic sandstone amendment on water retention in sandy land. The results showed that as the proportion of fine feldspathic sandstone in the sandy land soil increased, the soil texture changed from sand to silt loam, the capillary po- rosity gradually increased from 26.3% to 44.9%, and the soil saturated hydraulic conductivity decreased from 7.10 ram/rain to 0.07 mm/min. Feldspathic sandstone gravel formed micro-reservoirs in the sandy land soil, playing the role of a ＇water absorbent＇ and ＇water retaining agent＇ in sandy land. Amendment with feldspathic sandstone can increase water retention in the arable layer of sandy land by 67%. This study provides a theoretical basis for the amelioration of sandy land on a large scale. It can be concluded that amendment with feldspathic sandstone can improve the physical properties of sandy land soil and increase soil water retention.
基金Project(2006AA09Z336) supported by the National High-Tech Research and Development Program of China
文摘Petrographic analysis combined with various techniques, such as scanning electron microscopy and X-ray diffraction, was used to assess the timing of growth and original mineral cements, the controls on reservoir and reservoir quality of the fourth member sandstones of Shahejie formation (Es4). The Es4 sandstones are mostly arkose and lithic arkose, rarely feldspathic litharenite, with an average mass fraction of quartz 51.6%, feldspar 33.8% and rock fragments 14.6% (Q51.6F33.8R14.6). They have an average framework composition (mass fraction) of quartz 57.10%, K-feldspar 5.76%, sodium-calcium feldspar 13.00%, calcite 5.77%, dolomite 5.63%, siderite 0.95%, pyrite 0.30%, anhydrite 0.04%, and clay mineral 11.46%. The diagenentic minerals typically include kaolinite, illite-smectite (I/S), illite, chlorite, authigenetic quartz and feldspar, and carbonate and pyrite. Es4 sandstone has undergone stages A and B of eodiagenesis, and now, it is experiencing stage A of mesodiagenesis. Reservoir quality is predominantly controlled by the mechanical compaction, for example, 45.65% of the original porosity loss is related to compaction. The original porosity loss related with cementation is only 26.00%. The reservoir quality is improved as a result of dissolution of feldspar, rock fragment and so forth. The porosity evolved from dissolution varies from 3% to 4%.
文摘In order to understand the diagenesis and its influence on porosity and permeability of sandstones from Yingcheng Formation in Jinshan field,applying thin sections,casting and scanning electron microscope,the authors studied petrography,diagenesis,porosity and permeability of Yingcheng Formation sandstone reservoir. The results show that the reservoir of Yingcheng Formation is mainly composed of lithic arkoses. Sandstones experienced compaction,pressolution,cementation,metasomatism and dissolution. The primary pores of the sandstones are undeveloped; most of pores are the secondary pores,which are mainly intragranular dissolution pores in feldspar and debris. The compaction and cementation reduced the primary pores in sandstones,the porosity and permeability decreased; while the dissolution formed the secondary pores,resulting in the porosity and permeability increase. Due to compaction and cementation,the porosity and permeability are reduced with increasing of depth. There exists an abnormal enlargement of porosity and permeability within a depth range 2310--2450 m. In combination with analysis of petrology,the dissolution of feldspar and debris is most developed in the depth range. Therefore,compaction,cementation and dissolution are the important factors which affect the porosity and permeability of sandstones.
