Academic and also Experimental Rock Physics
Seismic signatures of uneven saturation A major initiative of the division is concentrated on the research study of the effects of irregular saturation on seismic trademarks. The major purpose is to measure the effect of random spatial distribution of fluid patches. The method is based upon the basic theory of heterogeneous poro-elasticity developed by CRGC over the last decade. The goal of the current effort is to develop a general model for elastic homes of partly saturated rock with a given statistical distribution of cracks and also with arbitrary contrast in between the properties of both liquids (e.g., gas as well as liquid). The department is additionally doing a series of liquid injection try outs X-ray Computer Tomography and ultrasonic control to confirm the theoretical findings. The impact of capillary forces on the flexible residential or commercial properties of partly saturated rocks is additionally being checked out. On field scale, the outcomes of academic research have been applied to time-lapse logs obtained at the Nagaoka carbon dioxide storage space site. geophysics perth
Modelling of stress dependent attenuation and also diffusion due to squirt flow in clastic and carbonate rocks The department has actually established a new squirt flow design in which all specifications can be independently measured or approximated from measurements. The pore area of the rock is presumed to consist of rigid porosity and compliant (or soft) pores present at grain get in touches with. The result of isotropically dispersed soft pores is modelled by taking into consideration pressure leisure in a diskshaped space between nearby grains. This derivation provides the complex and frequency-dependent efficient mass and shear moduli of a rock, in which the soft pores are liquid-saturated and stiff pores are dry. The resulting squirt design is consistent with Gassmann's and also Mavko-Jizba formulas at low and also high regularities, specifically. As anticipated, the dispersion and depletion are the best at low reliable tension and much smaller sized at greater effective stress. The division will be screening and also refining this design making use of ultrasonic and low-frequency measurements on clastic and also carbonate rocks saturated with various fluids. The design is also being extended to partial saturation, anisotropy and viscoelastic fluids.
Modelling of buildings of rocks filled with heavy oil Due to the fact that its viscoelastic rheology makes Gassmann theory as well as all its expansions inapplicable in concept, Rock physics for heavy oil is various from rock physics for conventional fluids. The division has actually created an approximate methodology for fluid substitution in heavy-oil tanks. The methodology is based on one specific equivalent-medium approach referred to as systematic possible approximation (CPA). The method has actually been effectively evaluated on low frequency lab dimensions Presently, the division is establishing a different model for heavy oil rocks based upon the principle of quasi-static squirt circulation.
Low frequency acoustic measurements. Academic rock physics models require to be checked and adjusted utilizing laboratory measurements. To this end, the division is doing thorough speculative screening of these concepts making use of broadband dimensions of dynamic elastic properties of rock samples. Experiments are carried out using a mix of forced-oscillation ultrasensitive stress gauge measurements (10 Hz-- 2KHz), laser interferometry (100 Hz-- 200 kHz) and also ultrasonic screening (1001000 kHz). The results are being compared with academic predictions computed utilizing numerical simulations.
Modelling flexible buildings of broken tanks A significant effort of the department's rock physics team is guided in the direction of designing depletion, dispersion and also regularity dependent anisotropy of porous storage tanks penetrated by aligned fractures. Over the last years, this team has created an approach of liquid alternative in fractured storage tanks, which is based on the combination of anisotropic Gassmann equations and also Schoenberg's linear slip parameterisation of the effect of cracks on rock homes. Between 2003 and also 2006, the group developed a model for attenuation and also diffusion of P-waves propagating perpendicular to a routine system of identical planar cracks and also verified this design with numerical simulations using a poroelastic expansion of reflectivity method. These simulations assisted to prolong the attenuation/dispersion design to arbitrarily spaced cracks as well as to oblique incidence.