Underground Storage and Geotechnology Systems. PCL a software for 3-D leaching simulation developed by UGS

Transcription

1 Underground Storage and Geotechnology Systems PCL a software for 3-D leaching simulation developed by UGS

2 PCL a software for 3-D leaching simulation developed by UGS Characteriz ation of the program PCL is an interactive software for the threedimensional (3-D) simulation of transient salt dissolution processes in salt caverns during - leaching operations, including SMUG solution mining under gas - liquid product storage operations (injection, withdrawal with water or under-saturated brine) - flooding of emptied caverns with fresh water or under-saturated brine with a cavern development around a vertical axis. The program is mainly intended to be used by experienced salt cavern design and operating engineers. It can take into account dipping salt layers with varying dissolution characteristic as well as anisotropic salt leaching behavior within these layers. The program is neither capable to simulate the development of fingers or pockets nor to consider such features of imported initial cavern shapes. The program allows for a gradual change of blanket level depth during an operating stage and therefore for the simulation of - leaching processes under gas (SMUG solution mining under gas) i. e. the leaching process continues while a large quantity of gas is injected to or withdrawn from the cavern); - product storage processes with fresh water or under-saturated brine for withdrawal. If required pressure loss calculations can be included on the operation stage level for both vertical and S-shape wells. The necessary thermo-physical properties are calculated by the program depending on the temperature. To define a start configuration the import of sonar survey data sets of different file formats is possible. The cavern shape development is instantly graphically displayed on the monitor screen while the calculation is still progressing. The import of leaching process data is possible (triple data set of date, freshwater flow rate, density of out-coming brine). The software can be run in - edit mode (design work, history match); - view mode (input data and result display without simulation capability); - admin mode (administration of default settings) PCL is characterized by high calculating speed. This allows for an inter-active adjustment of leaching parameters and immediate evaluation of the calculation results. German and English language versions are available. A user's guide and a dynamic help are an integrated part of the software. Picture 1 Cavern shape imported from sonar survey 2

3 The graphica l us er int erface Picture 2 The initially displayed windows can be changed in size, closed and again opened, minimized, detached and arranged in a different manner by drag-and-drop. The project structure window is always visible, it can neither be closed nor doubled. It exhibits the hierarchy of a project structure: - 1 st level represents the salt structure. A salt structure can encompass several caverns. - 2 nd level Represents a cavern project within the super-ordinated salt structure - 3 rd level Represents a calculation variant of the superordinated cavern project. Cavern variants are independent on each other. They can vary to a large extend. They can be copied and subsequently edited. - 4 th level Within a cavern variant salt layers with their dimensions, spatial orientation and specific leaching properties are to be specified. They can exhibit an anisotropic leaching behavior. operating stages with setting depths of the leaching strings, flow directions, flow rates, blanket position and the stage termination criterion are to be defined. A new operating stage inherits the properties of its predecessor and needs only an adjustment. Salt structure Cavern project 1 Cavern project 2 Cavern project 3 Cavern variant 3.1 Cavern variant 3.2 Cavern variant 3.3 Basic rock salt Salt layer 1 Salt layer 2 Operating stage 1 Operating stage 2 Operating stage 3 3

4 Graphical d isp lay of r e sults There are three different modes for the graphical display of the calculation results: 1. Cavern shape development during the calculation process The cavern shape is displayed in real-time during the calculation process. The blue shading reflects the mineralization distribution of the brine within the cavern (picture 3). While the computation process continues the cavern can be rotated. In this way dipping salt layers with different leaching properties can be visualized. When hovering with the mouse cursor over the graphic area spatial related data are displayed (picture 4). 2. Overlapping shapes Once the simulation process is finished the cavern shapes at the end of each leaching stage can be visualized in one picture by overlapping (picture 5). 3. Stage main characteristics The major technological parameters characterizing one or more leaching stages (setting depth of the leaching strings, flow direction, blanket level, sump level) are displayed in a single chart (picture 6). Picture 3 Cavern shape development during calculation Picture 4 Visualized dipping salt layers with anisotropic leaching behavior Picture 5 Overlapping cavern shapes Picture 6 4

5 Disp lay of numerica l r esults There are two different types of windows for displaying the numerical results: - Windows for the Overview mode The overview window displays the relevant data of each operating stage such as start and termination date, operating and standstill time, cavern volumes and volume increase, water consumption, brine volume produced and the termination criterion that finished this operating stage. - Windows for the time step mode The time step window displays the results of one or more time steps of the selected operating stage. Overview Gives an overview on chronological data characterizing the process schedule up to the selected time step. Process Gives an overview on the balance of the media involved up to the selected time step. Mineralization Mineralization distribution in the cavern versus depth at the selected time step. Geometry Gives a geometrical characteristic of the entire cavern (volumes, maximum diameter and cross section, partial volumes filled with blanket and brine and sump volume, etc.) up to the selected time step. Radii Displays the actual cavern shape in numerical form; azimuth values counted clockwise from north at the selected time step. Pressures Displays major pressure values at the selected time step if fluid dynamic calculation for the borehole is activated. Picture 7 Picture 8 Picture 9 Overview-window Overview-tab in the time-step-window Process-tab in the time-step-window Picture 10 Process-tab in the time-step-window for two time steps 5

6 Export of resu lt data The following PCL-data can be exported: - Leaching process data for further processing particularly with MS EXCEL or for the generation of diagrams. After the operating stages and the time steps are specified for which the data shall be further processed, the related parameters can be selected from a list. These data are then written into a text file which can be directly imported to MS EXCEL. - Cavern characteristics are depth depending data describing cavern properties like partial volume, cross section area, average diameter, mineralization, etc. for further processing particularly with MS EXCEL. - Cavern shape as input data for other IT-applications. In this way e. g. a 3-D-model of the cavern can be created by the SOCON software CavView which can be downloaded from the internet. Picture 11 Selection list for process data export Summary PCL is an effective, fast calculating software tool for the 3-D simulation of leaching processes. It is particularly suited for the planning of leaching operations. But furthermore it can be used for the simulation of liquid product storage operations, flooding processes and for history match based on data records from the leaching process. Experienced leaching engineers get easily acquainted with this tool due to its intuitive graphical user interface. Picture 12 Selection list for cavern characteristics data export 6