Flow Assurance Technical Section

Hello, I am working in Oil India Limited as a Flow Assurance Scientist. I have designed an OLGA wax deposition model for a 8 inch 37 km pipeline. While running my model I am observing that the Temperature drop predicted by the model is differing with the real time temperature drop as observed physically at different locations. So, i wanted to know that can we control the temperature drop of an OLGA model manually if it not matching with my real-time conditions. Moreover, I also want to know if it is possible for me to input different inlet temperature values in a model say for e.g. of 6 days my inlet temperature values varies for each day so can I input different inlet temperature values for each of the six days in one model or would i need to create different models for each day.

Would really like to have some help.!

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Mr. Yatish Khulbe
SRS - R&D Department
Oil India Limited
e-mail - yatish.khulbe@oilindia.in
Mob. - 9971593118
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Yes, you can manually "control" the temperature drop by tuning heat transfer parameters and inputting time-varying inlet temperatures in a single model. 

If the OLGA model's predicted temperature drop doesn't match field data, you can calibrate it by adjusting these specific inputs: 

• Overall Heat Transfer Coefficient (U-value): The simplest way to match real-time data is to manually override the calculated U-value. You can specify a fixed value or adjust the insulation thickness and thermal conductivity of the pipe wall layers in the geometry section.
• Ambient Conditions: Adjust the Ambient Temperature (T_ambient) and the Ambient Heat Transfer Coefficient (H_ambient). For buried pipelines, ensure you are using the correct burial depth and soil thermal conductivity.
• Minimum Inner Wall Heat Transfer: You can set a H_{min innerwall} to prevent the software from under calculating the internal cooling rate. 

You do not need to create six different models. OLGA is designed for transient simulations. 

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In addition to what Mr. Mehta mentioned, also have a look at how you are comparing the temperature measurements in terms of probe location in the field vs. in the model. Sometimes, they are not the same and can be a reason for the difference (after trying the previous options).

In OLGA it is possible to change the inlet temperature of the fluid with time and so no need for 6 different models at all. 

One more comment - not specific to this case, but modelling in general. OLGA is pretty powerful and complicated piece of software and one can make a lot of changes to match the observations. However, before getting into those, please review the objectives of the modelling exercise and establish what level of history match is good enough for achieving a prediction that can be used to make business decisions. 

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Regards,
Parthasarathi Bandyopadhyay
Energy Consultant
Bangkok Noi, Thailand
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Original Message:
Sent: 01-28-2026 12:57 AM
From: Dharmesh Mehta
Subject: OLGA Wax Modelling

Yes, you can manually "control" the temperature drop by tuning heat transfer parameters and inputting time-varying inlet temperatures in a single model. 

If the OLGA model's predicted temperature drop doesn't match field data, you can calibrate it by adjusting these specific inputs: 

• Overall Heat Transfer Coefficient (U-value): The simplest way to match real-time data is to manually override the calculated U-value. You can specify a fixed value or adjust the insulation thickness and thermal conductivity of the pipe wall layers in the geometry section.
• Ambient Conditions: Adjust the Ambient Temperature (T_ambient) and the Ambient Heat Transfer Coefficient (H_ambient). For buried pipelines, ensure you are using the correct burial depth and soil thermal conductivity.
• Minimum Inner Wall Heat Transfer: You can set a H_{min innerwall} to prevent the software from under calculating the internal cooling rate. 

You do not need to create six different models. OLGA is designed for transient simulations. 

Respected Sir,

Thank you very much for your valuable insight. I will try the suggested modifications in my model.

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Original Message:
Sent: 01-28-2026 12:57 AM
From: Dharmesh Mehta
Subject: OLGA Wax Modelling

Yes, you can manually "control" the temperature drop by tuning heat transfer parameters and inputting time-varying inlet temperatures in a single model. 

If the OLGA model's predicted temperature drop doesn't match field data, you can calibrate it by adjusting these specific inputs: 

• Overall Heat Transfer Coefficient (U-value): The simplest way to match real-time data is to manually override the calculated U-value. You can specify a fixed value or adjust the insulation thickness and thermal conductivity of the pipe wall layers in the geometry section.
• Ambient Conditions: Adjust the Ambient Temperature (T_ambient) and the Ambient Heat Transfer Coefficient (H_ambient). For buried pipelines, ensure you are using the correct burial depth and soil thermal conductivity.
• Minimum Inner Wall Heat Transfer: You can set a H_{min innerwall} to prevent the software from under calculating the internal cooling rate. 

You do not need to create six different models. OLGA is designed for transient simulations. 

Hi Yatish,

I hope you have at least generated a wax table with at least the wax appearance temperature (WAT) calibrated based on experimental data, but for this type of application I would extremely recommend to have also tuned the wax weight versus temperature, of course if you have experimental data with this.. 

Regarding your question related to the simulated temperature is not representing the field temperature, it is important to have in mind that the wax deposition creates an insulated layers, and if the wax table is not representing the experimental data, this could be one reason for the discrepancy between OLGA and field data. However, if we suppose that the table is representative, you have different options to adjust the heat transfer. I think the easiest way is to tune the HEATFLUX via FA-MODELS/TUNNING and selecting the pipes to use a different tunning factor.

In terms of your second question related to the possibility to change inlet temperature by time, all the boundary conditions objects (e.g. reservoir contact, pressure driven source, massflow source) and type of nodes (e.g. pressure, mass) have the capability to set the variables (e.g. temperature) by time (via TIME in property view window of the selected object). For example, below I put the increment of 10 oC of every day (in ramps of 0.01 d) starting with 40 oC and maintaining all the other boundary conditions constant. 

TIME: 0, 1, 1.01, 2, 2.01 [d]

TEMPERATURE: 2:40, 2:50, 60 [oC]

MASSFLOW: 5:1000 [kg/h]

GASFRACTION: 5:-1

TOTALWATERFRACTION: 5:0

We have other ways as mentioned by the other professionals in this post, but in my opinion the easiest one is via TUNNING.

Also remember one thing, OLGA just considers one energy equation, TM variable in the average fluid temperature in the cell, and consequently does not provide the cross section radial temperature. If your cell is bigger, or if the sensor is taking the temperature near the inner wall temperature, TM might not be representative. However, OLGA has the possibility to generate the inner wall surface temperature via TWS variable.

If you want more help, I would recommend to see tutorials in YouTube, or contact SLB support.

Regards,

Carlos Nascimento