Earth, Atmospheric, and Planetary Sciences - Master's degree
http://hdl.handle.net/1721.1/7656
Thu, 25 May 2017 17:34:01 GMT2017-05-25T17:34:01ZOn the relationship between compressional wave velocity of saturated porous rocks and density : theory and application
http://hdl.handle.net/1721.1/108912
On the relationship between compressional wave velocity of saturated porous rocks and density : theory and application
AL Ismail, Marwah I
Understanding the velocity of the compressional waves travelling through rocks is essential for the purposes of applied geophysics in such areas as groundwater and hydrocarbon exploration. The wave velocity is defined theoretically by the Newton-Laplace equation, which relates the wave velocity, V, to the square root of the ratio of the rock's elastic modulus, M, and its density, [rho] (Bourvie et al., 1987). Therefore, the equation indicates that the velocity is inversely proportional to density. However, the in-situ field measurements and laboratory experiments of compressional wave velocity through different rocks show otherwise. In other words, the velocity is directly proportional to approximately the 4th power of density as stated by Gardner (Gardner et al., 1974). This thesis investigates the inconsistency between theory and observations regarding the relationship between velocity and density of saturated porous rocks. The inconsistency is clarified by deriving a new expression for the elastic modulus, M, using Wyllie's time average equation and the Newton-Laplace equation. The new derived expression of the elastic modulus, M, provides dependence of M on density to approximately the 9th power. In addition, Gardner's equation is modified to accurately obtain the velocity over the entire range of densities (from 1.00 g/cm³ to around 3.00 g/cm³) and porosity (from 0% to 100%). The end of this thesis is an application of the previous outcomes with real data sets, where the results validate the derived expression of the elastic modulus as well as the generalized form of Gardner's equation.
Thesis: S.M., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2017.; Cataloged from PDF version of thesis.; Includes bibliographical references (pages 97-98).
Sun, 01 Jan 2017 00:00:00 GMThttp://hdl.handle.net/1721.1/1089122017-01-01T00:00:00ZCryogenic deformation of two comet and asteroid analogs under varying conditions of saturation
http://hdl.handle.net/1721.1/107110
Cryogenic deformation of two comet and asteroid analogs under varying conditions of saturation
Atkinson, Jared William Graham
Sample retrieval from extraterrestrial bodies and in situ resource utilization (ISRU) activities have been identified as some of the most important scientific endeavors of the coming decade. With the failure of Rosetta's Philae lander to penetrate the surface of comet 67P and obtain a sample due to the high compressive strength of the surface, it is becoming obvious that knowledge of the mechanical properties of materials that might be encountered in such environments and under such conditions is critical to future mission success. Two comet/asteroid analogs (Indiana limestone and Bishop tuff), selected based on their contrasting mechanical properties and porosities, were tested under constant displacement to failure (in most cases) at extraterrestrial conditions of cryogenic temperatures (295 K down to 77 K) and light confining pressures (1 to 5 MPa). The compressive strength of both materials was determined under varied conditions of saturation, from oven-dried (~0% water content) to fully saturated, and both brittle and ductile behavior was observed. The saturated limestone increased in strength from -30 MPa (at 295 K) to >200 MPa (at 77 K), while the Bishop tuff increased in strength from 13 MPa at 295 K to 165 MPa at 150 K. Additional experiments demonstrated that thermal cycling reduces the compressive strength of limestone, while an increase in confining pressure from 5 MPa to 30 MPa at 200 K significantly increases the strength (from 62 MPa to 85 MPa respectively) of saturated tuff. The results of this study will be useful to future sample retrieval missions or ISRU maneuvers. The large increase in compressive strength of these saturated materials at cryogenic temperatures means that future missions will need to prepare technology that has the energetic and mechanical capability to penetrate very hard substrates as they are likely to encounter.
Thesis: S.M. in Planetary Sciences, Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2016.; Cataloged from PDF version of thesis.; Includes bibliographical references (pages 65-70).
Fri, 01 Jan 2016 00:00:00 GMThttp://hdl.handle.net/1721.1/1071102016-01-01T00:00:00ZA comparison of electric and hydraulic approaches to fluid flow simulation and hydraulic parameters inversion
http://hdl.handle.net/1721.1/107108
A comparison of electric and hydraulic approaches to fluid flow simulation and hydraulic parameters inversion
Al Nasser, Saleh Mohammed
History matching and prediction of future performance of hydrocarbon reservoirs and groundwater aquifers are considered some of the biggest challenges facing hydrologists and petroleum engineers. The complexity of the simulation method, in addition to the huge amount of input data, makes evaluating the reservoir performance expensive. The conventional reservoir history matching procedure usually requires a trial and error process of altering various reservoir parameters and simulating the pressure distribution and field production, or what is known as 'Forward Modeling'. In this study, I propose the use of regular electrical arrays to simulate aquifer drawdowns. By representing reservoir hydraulic conductivities as electric resistors and storativities as capacitors, simulating the potential response gives results similar to that of solving the hydraulic flow equations. Scaling the electrical parameters results in an equivalent approximation of voltage and hydraulic head. A set of synthetic aquifer models with increasing structure complexity were simulated under the Dupuit-Fochheimer assumption of negligible vertical flow. Under the finite difference scheme, aquifers subjected to a constant pumping rate were modeled under different boundary conditions. The transient drawdown data curves from either a single well or multiple wells were obtained, and the reservoir data were inverted for the hydraulic parameters. Because both electrical and hydraulic approaches result in similar response, parameters inversion can be performed on either system. Consequently, the hydraulic equations were used in the inversion. Inversion was performed according to the method of damped least-square where the Jacobian matrix is decomposed by Singular Value Decomposition (SVD). Furthermore, hydraulic aquifers are attempted to be modeled with a binary conductivity structure, which is an effective medium of two hydraulic conductivities.
Thesis: S.M., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2016.; Cataloged from PDF version of thesis.; Includes bibliographical references (pages 96-99).
Fri, 01 Jan 2016 00:00:00 GMThttp://hdl.handle.net/1721.1/1071082016-01-01T00:00:00ZA preliminary study of industrial meteorology
http://hdl.handle.net/1721.1/107036
A preliminary study of industrial meteorology
Hogan, Marion G
Thesis (M.S.) Massachusetts Institute of Technology. Dept. of Meteorology, 1946.; Bibliography: leaf 30.
Tue, 01 Jan 1946 00:00:00 GMThttp://hdl.handle.net/1721.1/1070361946-01-01T00:00:00Z