Fitting Final History, Forecasting
This leads us to the final step, forecasting. In this example, we’ve begun to see the effects of the boundaries, but only just.
We’ve got to make a judgement. In the example, there are two different forecasts: a homogeneous forecast (in red) with an Arps b of 0.5 and a heterogeneous forecast (dotted pink) to use if we know the geology, using an Arps b of 0.8. It’s a judgement call, but we need to be conscious of the fact that it will affect the final answer.
To ensure more accurate production forecasts, we need to:
- Identify flow regimes – this is the single most important step.
- Fit final regime (the most recent history). What’s happened earlier really doesn’t matter that much.
- While forecasting:
- In boundary dominated flow, select most appropriate final ‘b’ value, which will come with experienced judgement and analogy.
- In transient flow, choose end of flow regime, and use your best judgement as to what the final b value will be.
- Use analogs (preferred) or models to assist with choices.
These are extra steps that are necessary to ensure the most accurate forecast possible. To best achieve these elements, you want to make sure that your decline curve software can help you do these things quickly and accurately. If you don’t have the necessary tools to help you in this area, the benefits of accurate forecasting suggest that you should consider getting them.
About the author:
Dr. John Lee, PhD
A world-renowned expert in the field of petroleum reservoir engineering, John Lee, holds BS, MS and PhD degrees in Chemical Engineering from The Georgia Institute of Technology and has been a leader in our industry for over five decades. He is best known for his recent publications and presentations on oil and gas reserves regulations and estimation, and production forecasting in unconventional gas reservoirs. He served as an Academic Engineering Fellow with the U.S. Securities & Exchange Commission (SEC) and was a principal architect of the modernized SEC rules for reporting oil and gas reserves.
3esi-Enersight is the E&P industry’s leading provider of solutions for integrated strategy, planning and reserves, trusted by thousands of executives and technical decision makers in companies that include NOC’s, Super Majors, Emerging Operators, investors and consultants. From corporate strategy and planning to operations, capital management and corporate and technical reserves, 3esi-Enersight solutions are deployed in every region of the globe, helping customers make better investment decisions across conventional, unconventional, onshore and offshore assets.
With over 400 customers worldwide, no other solution provider is trusted by more oil and gas companies to deliver the reserves evaluations they rely on and the petroleum investment plans critical to shareholders’ success.
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