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Production forecasting flowchart
A good forecast combines all six production forcasting building blocks in a numerical model. Two examples of flowcharts for deriving a production forecast are given in Fig 1 and Fig 2 Individual steps may be adjusted to local needs, but the overall workflow should always follow a similar pattern and adhere to the production forecasting minimal expectations.
INSERT Figure 1 Typical production forecasting flowchart (Pending permission approval)
Typical production forecasting flowchart steps
INSERT Figure 2 Typical production forecasting flowchart (Pending permission approval)
Fig 2 flowchart assumes that the forecast is made for a mature field with an IPSM (integrated production system model, but similar steps should to be considered for analog methods and DCA. If this is a green field model, similar steps should be carried out to calibrate the model with known analog performance.
Agree on objectives and forecasting strategy
Always start by agreeing on the objectives of the forecast and by deriving a forecasting strategy based on these objectives.
Once the objectives are clear, the appropriate input data must be gathered.
Calibrate the model
These steps of history matching and model calibration can be carried out in parallel and potentially by different discipline engineers. In this step, the model is conditioned for forecasting.
Match reservoir performance
Match long-term trends, such as pressure decline and water cut development, as well as 4D seismic.
Match well potential and surface constraints
Calibration of pressure drops in the wells, pipes and surface facilities.
Activity plans and up times
Planned and statistical activities with historical system availability (e,g., downtime).
Make the long-term forecast
Once the model is properly calibrated, the long-term forecast may be made by running the model to the agreed abandonment conditions.
Include operational forecast planning assumptions
After the long-term forecast has been derived and the reservoir decline is established, near-term activities should be included in the forecast.
Update Risk Register
Any uncertainty analysis should start with a risk register, which is kept evergreen for the field.
Develop uncertainty analysis low/best/high estimate
Uncertainty analysis is a key deliverable of any forecast.
Review and challenge
Forecasts should in general be peer reviewed by experienced peers or supervisors to get an independent view of the forecast quality. This may result in a feedback loop back to Step 4, to make the long-term forecast again with different assumptions as agreed during the review.
Apply adjustment factors
Even with the best geological model and tools, it may still be decided that the full reservoir heterogeneity is not captured in the model and further adjustments need to be applied to the forecast. Or actual project execution may be uncertain. In this case, a discount factor should be applied to the forecast.
Noteworthy papers in OnePetro
Production forecasts and reserves estimates in unconventional resources. Society of Petroleum Engineers. http://www.spe.org/training/courses/FPE.php
Production Forecasts and Reserves Estimates in Unconventional Resources. Society of Petroleum Engineers. http://www.spe.org/training/courses/FPE1.php