Tight gas is the general term applied to low permeability, low deliverability, and low porosity gas-producing formations. Future potential for gas production lies among others in tight gas reservoirs. Gas wells in these reservoirs are economically marginal and they cannot be developed using conventional technologies. These reservoirs must be hydraulically fractured to produce because of the natural ineffective reservoir drainage, which is due to extremely low permeability.

In this paper, an integrated approach was applied to investigate the role of rock mechanical properties. Also, samples were selected for microstructural and mineralogical characterizations using advanced microscopy and spectroscopy analytical techniques. Additionally, ultrasonic compressional and shear velocities were measured on each sample and dynamic Young's modulus and Poisson's ratio were obtained. The acquired topographical images showed the presence of nanoscale pores and micro-cracks in most of the examined core samples. The energy dispersive X-ray spectroscopy (EDS) general area analyses revealed that the examined formations were composed of oxygen, silicon, aluminum and magnesium as the major elements with appreciable amounts of potassium, calcium, iron and carbon. EDS spot mode analyses revealed the presence of white particles that were found to be iron-rich compounds. The outcome of this study is to develop practical empirical correlations to assist in predicting rock mechanical properties. The ultimate objective is to establish formation dependent correlations that relate mechanical properties, such as rock strength, to a log measured physical property such as sonic velocity. The mechanical properties are critical input for many field problems, such as wellbore stability, sand production control, fracturing, casing design and perforation. The final outcome of this project will result in tremendous reduction of testing time and cost.

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