Evaluation Of Petrophysical Properties Of Gas Shale And Their Change Due To Interaction With Water

Download or read book Evaluation Of Petrophysical Properties Of Gas Shale And Their Change Due To Interaction With Water written by Levent Yildirim and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Gas shale is a fine grained clastic, fissile sedimentary rock of gray/black color formed by consolidation of clays and silts. Successful petrophysical evaluation and stimulation treatments with horizontal drilling and hydraulic fracturing enable economic shale gas production. Shale gas development has contributed about 35 % of natural gas supply in US in 2013.Detailed evaluation of gas shales before and after stimulation treatments is a prerequisite to optimize gas production. Complex pore network in gas shales may result in inaccurate evaluation of petrophysical properties with traditional petrophysical models. Therefore, in this research we proposed a new methodology comprising a new understanding of evaluation of porosity, maturity analysis, geomechanical properties and initial gas in place calculations of gas shale via well logs and core analysis based on a new petrophysical model. We applied the methodology in a case study to investigate a Marcellus shale well in evaluating maturity, porosity and geomechanical properties to calculate initial gas in place and reserves and optimize stimulation designs. In the second part of this study, we conducted acoustic travel time measurements of Green River shale samples parallel and perpendicular to bedding plane before and after interaction with water to observe how shale interacts with water at different interaction times and bedding planes by analyzing change in acoustic velocity and mechanical properties before and after treatment to optimize stimulation designs. X-Ray diffraction analysis, scanning electron microscope imaging and horizontal and vertical permeability measurements of Green River shale samples using helium are conducted to characterize the samples by observing mineralogy, pore network and how permeability changes at different in-situ conditions. Therefore, the first and second parts of this research relate with utilization of well logs and core analysis to evaluate petrophysical properties of different gas shale formations.Maturity analysis, porosity evaluation and initial gas in place results of field case study of Marcellus shale show that total organic carbon content directly relates with porosity and adsorbed gas in place occupied in organic matter. Comparison of young's modulus and minimum in-situ stress values between Marcellus shale zone and adjacent boundaries are used for determination of stimulation interval in Marcellus Formation. An effective hydraulic fracturing treatment can be applied within the upper Marcellus Formation because of relatively higher minimum in-situ stress contrast between Stafford Limestone and upper Marcellus Formation. Closer porosity results of Marcellus shale when compared to that in literature and sufficient reserves suggest that density/resistivity separation method is more reliable than sonic/resistivity separation method. X-Ray diffraction and SEM images suggest that Green River Formation samples are dominantly comprised of carbonate minerals. Permeability measurements indicate that Green River Formation samples having very low permeability at various confining stresses needs to be stimulated effectively. Acoustic travel time measurements of Green River shale before and after interaction with water show that compressional and shear velocities increase as confining stress increases. Shear, young's and bulk modulus of Green River shale increase resulting in more rigid samples having more fracture conductivity as confining stress increases. Compressional and shear velocities decrease as Green River shale is exposed to water since minerals are dissolved by water solution and salinity of the samples decrease so that shear, young's and bulk modulus of the samples slightly decrease resulting in less rigid samples having lower fracture conductivity.The new methodology of petrophysical evaluation of gas shale based on the new petrophysical model serves a new understanding of evaluation of maturity analysis, porosity and mechanical properties and initial gas in place calculations of gas shale by utilizing well logs in field and core analysis in laboratory.