Within fractured reservoirs, such as tight gas reservoir, coupled processes between matrix deformation and fluid flow are very important for predicting reservoir behavior, pore pressure evolution and fracture closure. To study the coupling between gas desorption and rock matrix/fracture deformation, a poroelastic constitutive relation is developed and used for deformation of gas shale. Local continuity equation of dry gas model is developed by considering the mass conservation of gas, including both free and absorbed phases. The absorbed gas content and the sorption-induced volumetric strain are described through a Langmiur-type equation. A general porosity model that differs from other empirical correlations in the literature is developed and utilized in a finite element model to coupled gas diffusion and rock mass deformation. The dual permeability method (DPM) is implemented into the Finite Element Model (FEM) to investigate fracture deformation and closure and its impact on gas flow in naturally fractured reservoir. Within the framework of DPM, the fractured reservoir is treated as dual continuum. Two independent but overlapping meshes (or elements) are used to represent these kinds of reservoirs: one is the matrix elements used for deformation and fluid flow within matrix domain; while the other is the fracture element simulating the fluid flow only through the fractures. Both matrix and fractures are assumed to be permeable and can accomodate fluid transported. A quasi steady-state function is used to quantify the flow that is transferred between rock mass and fractures. By implementing the idea of equivalent fracture permeability and shape-factor within the transfer function into DPM, the fracture geometry and orientation are numerically considered and the complexity of the problem is well reduced. Both the normal deformation and shear dilation of fractures are considered and the stress-dependent fracture aperture can be updated in time. Further, a non-linear numerical model is constructed by implementing a poroviscoelastic model into the dual permeability (DPM)-finite element model (FEM) to investigate the coupled time-dependent viscoelastic deformation, fracture network evolution and compressible fluid flow in gas shale reservoir. The viscoelastic effect is addressed in both deviatoric and symmetric effective stresses to emphasize the effect of shear strain localization on fracture shear dilation. The new mechanical model is first verified with an analytical solution in a simple wellbore creep problem and then compared with the poroelastic solution in both wellbore and field cases.

methane and other higher order hydrocarbons, through C4, with interest in further developing reactions important to methane- and ethane-related chemistry. With the increased demand for energy and the declining conventional hydrocarbons worldwide, energy companies, both majors and independents, are turning to unconventional resources to produce the hydrocarbons required to meet market demand. From coalbed methane to low permeability (tight) gas reservoirs and gas shales, energy companies are making substantial progress in developing the technologies required to bring these unconventional reserves to the market. A common misconception is that there are not enough domestic oil and gas reserves to fuel our economy. The United States imports most of the oil used for transportation fuel and several TCF of natural gas annually. However, there is a very large resource of natural gas in unconventional reservoirs, with over 2,200 TCF of gas in place in just the gas shale formations that have been identified in the energy arena (Navigant Study 2008). There are still major gas shale plays and basins that have not been explored and are waiting to be evaluated and developed. The natural gas in shales and other unconventional reservoirs can be used to generate electricity, or it can be turned into liquids and used by the transportation industry. It is also misconstrued that gas shales are relatively new in our industry and something of the future. The first commercially viable gas shale well was drilled in the early 1920s in Pennsylvania, before the famous oil well drilled by Colonel Drake. The objectives of this study are to (1) complete literature review to establish which geologic parameters affect completion techniques in five emerging gas shales: the Antrium, the Barnett, the Haynesville, the Marcellus, and the Woodford; (2) identify the different completion methods; (3) create an economic model for the completion techniques discussed; (4) develop a sensitivity analysis on various economic parameters to determine optimal completion strategy; and (5) create completion flowcharts. Based on the literature review I have done for several gas shale basins, I have identified seven pertinent geologic parameters that influence completion practices. These are depositional environment, total organic content (TOC), average gas content, shale mineralogy, shale thickness, and reservoir pressure. Next, I identified different completion and simulation trends in the industry for the different shale plays. The results from this study show that although there are some stark differences between depths (i.e. the Antrim Shale and the Haynesville Shale), shale plays are very similar in all other geologic properties. Interestingly, even with a large range for the different geological parameters, the completion methods did not drastically differ indicating that even if the properties do not fall within the range presented in this paper does not automatically rule them out for further evaluation in other plays. In addition to the evaluation of geologic properties, this study looked at drilling cost and the production profile for each play. Due to the volatility of the energy industry, economic sensitivity was completed on the price, capital, and operating cost to see what affect it would have on the play. From the analysis done, it is concluded that horizontal drilling in almost any economic environment is economic except for one scenario for the Woodford Shale. Therefore, gas shales plays should still be invested in even in lower price environments and companies should try to take advantage of the lower cost environments that occur during these times. With continual development of new drilling and completion techniques, these plays will become more competitive and can light the path for exploration of new shale plays worldwide.

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The Upper Cretaceous Alderson Member is a prolific gas (biogenic) producer in western Canada. In the Hatton Gas Pool area (southwest Saskatchewan), Alderson Member strata from ten drill-cores have been examined and classified based on sedimentological and ichnological character. Core analysis has determined that Alderson Member deposits comprise thick intervals of pervasively bioturbated strata. Using spot-minipermeametry and high-pressure mercury injection porosimetry methods, the influence of pervasively bioturbated intervals on the overall resource potential of Alderson Member strata is evaluated. Results from permeability and porosity testing demonstrate that pervasively bioturbated rock fabrics appear to locally enhance the overall storage and vertical transmission of gas from Alderson Member reservoirs.