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Some Geomechanical and Petrophysical Linkages Within Paleo-Sedimentary Beds of Ghana

M. Affam, D. Abdulai, C. Nyarko

Abstract


Instability issues have been a major challenge in the Sekondian Series of South-Western Ghana. This is particularly affecting civil works and environmental mitigation efforts across the formation as extensive weathered profile impedes structural integrity. Uniaxial Compressive Strength (UCS) of lithological units which is a critical stability measure in most engineering projects requires quality sample of appropriate dimension for its determination. Samples for this important design parameter cannot be easily obtained from the Sekondian sedimentary strata, except at deeper depth, requiring extensive drilling. However, the parameter could be inferred from other properties of the rockmass.This research examines some geomechanical and petrophysical properties of the EfiaNkwanta beds by correlation and regression analysis to obtain models for stability inference. The models were established with the t-test and F-test using Minitab programming. The analysis was performed on disaggregated samples from the beds. The test methods employed were UCS, porosity, saturation and particle density. Correlation interpretation was based on Correlation Coefficients and P-value whereas regression analysis was based on R-square, the P-value and Residual standard deviation. The results indicated that linear association existed between the UCS and Porosity within the sandstone of well sorted grains and connected pores. Thus, the compressive strength of the sandstone was found to be dependent on the degree of pore connectivity. The EfiaNkwanta sandstone gave the best linear correlation with the rest showing appreciable dependence.

 

Keywords:Sekondian Series,petrophysical, geomechanical, correlation analysis, uniaxial compressive strength, porosity

Cite this Article: M. Affam, D. Abdulai, C. Nyarko. Some Geomechanical and Petrophysical Linkages Within Paleo-Sedimentary Beds of Ghana. International Journal ofGeological and Geotechnical Engineering. 2020; 6(1): 31–42p.


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DOI: https://doi.org/10.37628/jgget.v6i1.613

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