| Title | The Boundary Element Method and the natural state of geothermal submarine systems |
|---|---|
| Authors | Mario César Suárez-Arriaga |
| Year | 2006 |
| Conference | Mexican Geothermal Congress |
| Keywords | Boundary Element Method, submarine systems, mathematical simulation |
| Abstract | In this work is presented a new method to estimate the initial state of geothermal submarine reservoirs and an evaluation of the amount of energy contained in these important natural systems. To evaluate the natural state of these reservoirs we use the classical Boundary Element Method (BEM) and suggest a simple way to couple this technique to the simulator TOUGH2 of the Lawrence Berkeley National Laboratory through the INPUT file. Submarine geothermal reservoirs contain essentially an infinite amount of energy. The deep submarine heat is related to the existence of hydrothermal vents emerging in many places along the oceanic spreading centers between tectonic plates. These systems have a total length of about 65,000 km in the Earth’s oceanic crust. The deep resources are located at certain places along the rifts between tectonic plates of the oceanic crust at more than 2000 m below sea level. Shallow resources are found near to continental platforms between 1 m and 50 m depth and are related to faults and fractures close to the coasts. Both types of resources exist in the Gulf of California, Mexico. To model these systems the initial mathematical problem is expressed in terms of boundary integral equations, fundamental solutions and boundary conditions of mixed type. The main field functions are pressure and temperature. The versatility and power of the BEM allows the efficient treatment of very complex or unknown reservoir geometry, without requiring discretization of the whole domain occupied by the system. This capability allows efficient testing of different boundary conditions to estimate several thermodynamic initial states at any desired interior point of the domain occupied by the reservoir under specific conditions. Unfortunately, the classical BEM is limited to single-phase flow in homogeneous media and cannot be fully applied to flow problems in heterogeneous systems. In this last case there is no fundamental solution. To overcome this difficulty after an initial state is estimated, TOUGH2 can be used to improve the initial simulation. The few available data on hydrothermal vents are very useful to estimate the amount of energy flowing from the ocean floor. In this way, it is possible to estimate initial conditions knowing only heat fluxes and temperatures at fissures and chimneys using this hybrid technique. |