Heterogeneity in mudstone/shale layers has significant effects on seal layer integrity. The presence of intralayer sandstone channels in a seal layer may allow the buoyant CO2 to escape from the reservoir, even if the globally averaged permeability of the seal layer seems low enough. On the other hand, multi-layered structures are known to work often as baffles for the upward migration of CO2 in formations. In this paper, we investigate the storage capacity of multilayer formations with discontinuous seals. Numerical simulations are carried out to study the effects of seal layer discontinuity on the long-term behaviour of CO2 injected into deep saline aquifers. To represent a seal layer composed of low permeability rocks intersected by sandstone channels, ‘MINC' doubleporosity model is adopted. Also conducted is sensitivity analysis to investigate the effects of key parameters such as capillary pressure, relative permeability, temperature, and the thickness of the formations. The results show that CO2 injection into a sufficiently deep multi-layered reservoir enables CO2 to be stored and trapped in and around the reservoir without reaching to a shallow aquifer, even though seal layers have discontinuities. The upward movement of CO2 is greatly affected by capillary pressure of sandstone channels in seal layers. The relative permeability and the temperature-dependent CO2 properties have a significant effect on the final plume spread and the amount of CO2 dissolved or fixed by residual gas trapping.
The objective of this study is to clarify the zinc removal mechanism and construct a quantitative model for column experiments using a natural component of organic soils, namely leaf mold. We performed column experiments using actual acid mine drainage (AMD) at several conditions. After column experiments, the residues in the column were analyzed by x-ray absorption fine structure (XAFS) analysis. These experimental results highlighted that when leaf mold, limestone, and iron powder were filled in the column, the zinc removal mechanism was not only surface complexation for leaf mold but also the formation of zinc sulfide. Whereas, when only leaf mold was filled in the column, that was only surface complexation for leaf mold. Based on the above results, we constructed a quantitative model incorporating surface complexation by leaf mold, sulfate reduction reaction by sulfate-reducing bacteria, Fe2+ dissolved reaction from leaf mold, and one-dimensional transport against the height of the column. The experimental results of pH and the concentration of each element were successfully represented by the quantitative model.
Since multi-national oil development companies (herein after referred to as “companies”) employ significant CSR in the Federal Republic of Nigeria (herein after referred to as “Nigeria”), CSR in Nigeria is examined in this study. CSR has changed from only pursuing a “corporate objective”, which aims to achieve companies' stable operations, to emphasizing a “development objective” through which the “corporate objective” could still be achieved. However, it has been suggested that the “development objective” oriented CSR has not always been effective because companies had a tendency to emphasize the “corporate objective”, and the “development objective” was often incompatible with the “corporate objective”. Also, it has been suggested that government failure in its community development increased the people's expectation of companies to provide community development and that community development by CSR might ease the pressure on the government to undertake a developmental role. This study examines these points and the results are as follows. Since some CSR cases were found to have achieved both the “development objective” and the “corporate objective” simultaneously, it is possible that these objectives can be achieved in concert. Many of the people who expected community development by companies responded that companies had a responsibility to pay compensation for oil extraction from the Niger Delta/Nigeria, some responded that companies had social responsibility, and a few responded that companies may have been able to provide effective community development for their CSR. Furthermore, it has been inferred that companies were expected to pay compensation even though they payed taxes to the government, because the government provided only limited community development using these tax receipts. Thus, it appears that, expectation of compensation for oil extraction by companies and their social responsibility, as well as limited community development by the government, are the major factors that could increase the people's expectation of companies to provide community development and ease the pressure on the government.