This paper was prepared in response to a request by a respondent to the attendee questionnaire at the PSIG 2005 Annual Meeting in San Antonio, Texas. The request correctly implied that authors always talk about the great things provided by pipeline simulation, but never discuss the problems. The author has been involved with many pipeline simulation projects over 30 years, and has had many things go wrong in the course of developing, using, or implementing pipeline simulators. This paper discusses many of the problems encountered by the author, following the format:
Problem - Definition of the problem
Cause - The reason for the problem
Solution - What was done to solve the problem
Notes - Rather subjective comments by the author with in the hope of aiding a general understanding of what is involved in successful pipeline simulation projects.
Ultimately, all problems are managementproblems! However, the following factors areoften not dealt with by management in time toprevent problems with the simulators:
Model Deficiencies - Model deficiencies are less common than they were a few years ago. There are many simulators available now that are essentially complete and correct. Problems still arise in setting proper time and distant steps, and in setting correct operating parameters. There are also still a few things about pipelines, such as the transition between laminar and turbulent flow, which are not completely understood.
Bad Data - There will always be bad data, in the sense of instrumental or encoding errors. The issue is one of finding and correcting the errors, and designing the simulator so that it does not become hopelessly disabled in the meanwhile. There is also inaccurate information or assumptions about such things as ground thermal properties or pipeline roughness. The best real-time simulators can determine better values of these quantities by automatic tuning.
Configuration Errors - There will also always be configuration errors. Finding and correcting such errors is a major part of any simulator implementation. It is essential that the user be able to readily create and change configurations.
Unrealistic (Impossible?) Expectations - Both users and vendors are responsible for understanding and making clear the true capabilities of a simulator and applications based on it. Overselling will only work if there are customers wanting more than they can understand or are willing to pay for.
Computer Problems - Computers are amazingly reliable. Most computer problems are caused by conflicting uses.
Inadequate Instrumentation - This type of problem applies primarily to real-time simulations. If there are not enough measurements to provide boundary conditions, no unique solution can be found. If measurements are spaced too far apart, accuracy and response time will suffer. Generally, real-time models need additional measurements for tuning of unknown parameters, such as ground thermal properties. There are special situations, e.g. If the temperature of the fluid reaches equilibrium before the fluid reaches the end of the pipe, intermediate temperature measurements are needed.
