PanMesh™ Software Technology Overview
PanMesh software is an add-on to PanSystem®,Weatherford’s market leading well test analysis software. PanMesh software uses finite element numerical modeling to simulate well tests involving typical modern "real world" complexity. In particular, we have designed it so it can handle a wide range of well testing questions facing the petroleum engineer:
- Is my geological model correct?
- What impact is the well completion having on the well test and on well performance, and how do I assess it?
3D Visualization Model in PanMesh software
PanMesh software allows these questions to be answered by permitting a very fast and simple construction of a representative reservoir model, based if desired on a geological map. Fast and very accurate simulation of the well test is one benefit, but of equal usefulness is the way the product allows a multi-disciplinary team to appreciate what is happening in the reservoir during a test using 3D Visualization
The combination of PanSystem with PanMesh software allows well data to be transformed into information and then into real knowledge about the reservoir. The value obtained from a well test is magnified as a result.
PanMesh software is a Windows program developed to run with PanSystem software to address the need to extend the capabilities of traditional analytical well testing techniques. Based on finite element technology the program can be used to calculate the pressure response for reservoirs and wells in a wide variety of cases not covered by analytical models. The objective of the program is to accurately model the more complex well testing cases analytical techniques fail to address while at the same time retaining the efficiency of the traditional approach. The software uses automatic mesh generation, exports its results as type curves back to PanSystem software.
Work Flow
- Describe the Geological Model
- Describe Well Completion
- Enter Fluid Data
- View Model
- Simulate
- View Results
- Overlay in Pan
The user sets up the well, reservoir and fluid description in PanSystem software before starting PanMesh software. The description can start with one of the templates provided or the user can import a scanned map image.
PanMesh software then takes this description and automatically generates a finite element mesh from the well to the outer boundary. The default settings in the programs have been defined to ensure an adequate degree of fineness in the mesh for the purposes of calculating a pressure response. The user can select from four settings including a finer mesh if desired though the execution time will be higher. The mesh is displayed in three dimensions and can be viewed from any angle and distance to quality control the model.
The pressure response is then calculated – a matter of seconds or a few minutes for most geometries and the resulting draw down equivalent response generated on- screen as the simulation proceeds. While the simulation is proceeding the pressure distribution in the reservoir is displayed as a moving color map – this can be stored for subsequent replay.
A point within the reservoir may be chosen in addition to the wellbore at which the pressure response is output allowing interference effects to be analyzed.
The dimensionless pressure response is then transferred to PanSystem software where it is convolved with the wellbore storage and rate history to generate the real pressure versus time response. The resulting pressure curve can then be compared with measured data, saved as a specialized type curve, exported or processed in the same way as any other pressure data in PanSystem software.
Finite Element Technology
Finite element modeling is a widely accepted technique for engineering design and modeling For well testing the approach offers some specific benefits. The method deals naturally with layered, non-homogeneous geological strata and the twenty – noded iso parametric brick used to generate the mesh conforms accurately to all external boundaries and internal interfaces. The solver technology used in PanMesh software is very fast and the simple set up procedure makes the complete process very efficient.
Geometry
Modern drilling and completion techniques can produce wells with a wide range of geometries. On setting up the data model in PanSystem software different layers and an altered zone around the well can be defined to model skin factors and the deviation of the well can be set to any value. The well can be completed partially to model those reservoirs not fully perforated. Regions can be defined throughout the reservoir with varying properties such as permeability. A number of templates are provided which assists users in building a model to match their reservoir from a starting approximation.
Visualization
The data transferred from PanSystem software are used to define, rapidly and automatically, the finite element mesh from the wellbore to the outer boundary. This mesh can be viewed in PanMesh software as a solid model or as a wire frame and can be rotated and viewed in section or plan. The mesh can be set as Coarse, Medium, Fine or Superfine so if the pressure response shows some noise or instability on the coarse setting, the meshing algorithm can be run again on a finer setting. When the user is satisfied with the mesh, the simulation is started and as it proceeds the log-log plot of the draw down equivalent response is created while the pressure distribution in the reservoir is displayed in color contouring in a separate window. The initial color transition is set to occur at a Pd=.1 following the conventional definition of depth of investigation. At the end of the simulation the user can run through the simulation from start to finish viewing the pressure transient as it moves through the reservoir. This can be done in plan or section and the final display of the end-point represents the semi steady state pressure and flow distribution around the well. The pressure transient response display can be stored for playback later allowing useful comparison between different model characteristics.
The data generated is then transferred to PanSystem software for completion of the analysis.
Accuracy
The accuracy of PanMesh software has been validated by detailed comparison of the simulation results with a wide range of analytical reservoir and boundary models. The default settings for the mesh, the simulation time and other parameters have been selected to ensure the user needs make only minimal changes to achieve satisfactory results.
Development
The release of the second major upgrade to PanMesh software provides a new platform for the delivery of well test analysis technology. User experience is already proving that the application is capable of addressing a wide range of the industry’s requirements. As with all Weatherford software, continued investment will ensure that the software continues to evolve to meet users needs.
Conclusion
PanMesh software delivers the benefits of accurate numerical well test analysis while retaining the ease of use and flexibility of traditional well testing packages. Its wide applicability means that there are few oil and gas field developments that would not benefit from its use.
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