scholarly journals Experimental Investigation on Organic Matter Orientation Characteristics of Terrestrial and Marine Shale in China

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-21
Author(s):  
Dunqing Liu ◽  
Hongkui Ge ◽  
Yinhao Shen ◽  
Kui Zhang
Keyword(s):  
Organic Matter ◽  
Isotropic Medium ◽  
Clay Content ◽  
Longmaxi Formation ◽  
Orientation Degree ◽  
Clay Particles ◽  
Marine Shale ◽  
Directional Alignment ◽  
Layered Clay ◽  
Electron Microscope Image

As an essential component in shale, OM (organic matter) grains and their arrangements may play essential roles in affecting the anisotropy of the reservoir. However, OM grains are commonly treated as an evenly distributed isotropic medium in current studies, and few works have been done to investigate their detailed arrangement characteristics. In this study, terrestrial and marine shale samples were collected from three different shale plays in China, and the arrangement characteristics of OM grains in each sample were investigated by SEM (scanning electron microscope) image analysis. The results indicate that OM grains in shale are not evenly distributed in isotropic medium, and their directional alignment is pervasive in both marine and terrestrial shale. OM grains in shale tend to subparallel to the bedding section, and their orientation degree and controlling factors differ among different shales. OM grains in samples from terrestrial C-7(Chang-7 Formation) exhibit the strongest directionality in their arrangement, and OM grains in samples from marine LMX (Longmaxi Formation) shale in the Fuling area also exhibit strong directional alignment. While in samples from marine LMX shale in the Baojing area, their directional alignment is much weaker. Shales with high clay content, high TOC (total organic carbon), low thermal maturity, and flat reservoir structure get more OM grains parallel to the bedding section. The biogenetic texture of graptolite in marine LMX shale is the dominating factor leading to the strong directional alignment of the OM grains. However, syncline structure may disorganize the preformed directional alignment and weaken the directionality of the OM grains, which results in the OM arrangement difference between LMX samples from Fuling and Baojing. While the compaction of the layered clay particles is the dominating mechanism leading to the strong directional alignment of the OM grains in terrestrial shale samples from C-7.

CLAY ILLUVIATION IN SOME ORTHIC PODZOLS OF EASTERN CANADA

1965 ◽  
Vol 45 (2) ◽  
pp. 127-138 ◽  
Author(s):  
J. E. Brydon
Keyword(s):  
Organic Matter ◽  
New Brunswick ◽  
Iron Oxides ◽  
Clay Content ◽  
Granular Structure ◽  
Charge Component ◽  
Eastern Canada ◽  
Free Iron ◽  
Fine Clay ◽  
Ph Dependent

The Arago, Barney, and Holmesville soils, Podzols from Quebec, Nova Scotia, and New Brunswick, respectively, each had friable Bfh horizons with moderate granular structure, and with organic matter and free Fe2O3 contents greater than the Ae and C horizons. The Arago and Holmesville had thin Bhft horizons containing over 10% organic matter and 5% free iron oxides. The C horizons of these two soils had some features characteristic of fragipans.The B horizons of the three soils had a high "pH-dependent charge component" in the C.E.C. values. The "permanent charge component" was similar throughout the Arago profile except for the Bhft horizon where clay accumulation had occurred.Translocation of clay from the Ae to the upper B horizons was indicated by the twofold increase in clay content and the relative enrichment of fine clay in the B horizons. Removal of free iron affected the clay contents differently in the different: horizons but the maximum clay content in the upper B horizons remained. The definitions of Orthic Podzols, Textural Podzols, and t horizons should be re-examined.

scholarly journals Soil fertility status of some of the intensive crop growing areas under major agroecological zones of Bangladesh

2016 ◽  
Vol 41 (4) ◽  
pp. 735-757 ◽  
Author(s):  
NC Shil ◽  
MA Saleque ◽  
MR Islam ◽  
M Jahiruddin
Keyword(s):  
Organic Matter ◽  
Soil Fertility ◽  
Calcareous Soils ◽  
Clay Content ◽  
Soil Samples ◽  
Exchangeable K ◽  
Low Level ◽  
Fertility Status ◽  
Agroecological Zones ◽  
High Level

Laboratory studies on soil fertility evaluation was carried out across major agroecological zones (AEZs) of Bangladesh to know the nutrient status of soils and to relate those with soil properties like pH, organic matter, CEC, and clay content. Thirty five composite soil samples were collected from intensive crop growing sites, which covered 17 AEZs of Bangladesh. After proper processing, the samples were analyzed for texture, pH, organic carbon, CEC, exchangeable cations (K, Ca, Mg and Na), total N, available P and S following standard methods. The textural class of the soils collected from AEZ 12 and 13 appeared to be mostly clay. Clay loam soil was found in AEZ 4, 8, 9, 11, 25 and 28. Loamy soil was seen in AEZ 1 while AEZ 22, 23 and 29 were mostly sandy textured. The results revealed that 65.7% of the tested soil was acidic while 25.7% was alkaline in nature. All the tested soils showed lower pHKCl compared to pHH2O thus possessed negative charge. About 68.6% of the collected soils contained low (1.10-1.70%) level of organic matter, 25.7% soils retained it at medium level (1.71-2.40) and 5.7% soils at very low level (<1.0%). All the tested soils appeared to be deficient (< 0.12%) in nitrogen content. 68.6% soil samples had the low level of available P while only 8.6% retained it an optimum amount. About 80% of the tested soils contained low level of available S (7.9- 14.7 mg kg -1) although coastal regions soils hold higher amount of available S. High CEC (20-38 cmol kg-1) was found in clay rich soils of AEZ 10, 11, 12, and 13. Study revealed that 40% of the collected soils were very low, 31.4% were low, 8.6% each of medium and optimum, and 11.4% contained high level of exchangeable K. The calcareous soils (AEZ 10, 11, 12 and 13) contained very high level of Ca. Non calcareous soils also showed fairly good level of Ca content except AEZ 1, 3, 23 and 29. Sandy textured soils of greater Dinajpur, Rangpur, Moulvibazar showed lower level of exchangeable Mg. About 86% of the tested soils had the lower (< 2%) potassium saturation percentage (KSP), which needs K application for sustainable crop production. Estimate showed that 44% variability for CEC may be attributed by clay content and the relationship was significant (p = 0.05). Again, 50.4 and 65.6% variability in exchangeable K and Mg, respectively may be governed by clay content of the soils, while such relationship for Ca was non-significant. CEC may contribute 62.2, 92.3 and 83.9% variability for exchangeable K, Ca and Mg content in soils, respectively. The fertility status of most of the studied soils (except AEZ 10, 12, 13 and to some extent 11) appeared to be low to very low, which demand judicious management in order to achieve food security and to conserve the soil fertility.Bangladesh J. Agril. Res. 41(4): 735-757, December 2016

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