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How Can Machine Learning Add Value to Making Inferences from Real Reservoir Data?. Vasily Demyanov Nathan Amaral , Julie Halotel , Tom Buckle, Rhona Hutton. Reservoir Challenges. Discover. Describe. Predict. Decide. Variability and heterogeneity in subsurface models.
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How Can Machine Learning Add Value to Making Inferences from Real Reservoir Data? Vasily Demyanov Nathan Amaral, Julie Halotel, Tom Buckle, Rhona Hutton
Reservoir Challenges Discover Describe Predict Decide Variability and heterogeneity in subsurface models On resource development with confidence under uncertainty Patterns in geological & reservoir data subject to uncertainty Outcomes of subsurface resources development Interpretable AI
Reservoir Challenges Discover Describe Predict Decide Variability and heterogeneity in subsurface models On resource development with confidence under uncertainty Patterns in geological & reservoir data subject to uncertainty Outcomes of subsurface resources development Interpretable AI
Discover Patterns in geological & reservoir data
Facies classification challenge Bias Uncertainty Petrophysiycal interpretation Sedimentological interpretation Halotel, McCarty, Gardiner, Demyanov, 2019, IAMG conference
Real field application – North Falkland Hybrid Event bed (HEB) Scenario B Flow partitioning Flow transformation Turbulent flow Mixed flow: debris flow and turbidity current Bipartite laminar/turbulent flow Turbidite Scenario A Halotel, McCarty, Gardiner, Demyanov, 2019, IAMG conference
Alternative depositional scenarios • Thick package of sandstones: • Good porosities • High NTG • No barrier to vertical flow Scenario B • Fine grain layers: • Greater range of porosity with low outliers • Lower NTG • Potential additional barrier/baffle to flow Scenario A Halotel, McCarty, Gardiner, Demyanov, 2019, IAMG conference
What are the right input features? INPUT: wireline logs + engineered features OUTPUTPredicted True GR SP NPHI GR Resdiff RHO Random Forest(RF) Classification Leo Breiman, 2001 Halotel, McCarty, Gardiner, Demyanov, 2019, IAMG conference
Feature importance • RF classifier gave more weight to the features commonly used by an expert • OWC becomes unimportant if data has no information about its impact► Leads to poor classification below OWC 1.0 0.8 0.6 0.4 0.2 0.0 1.0 0.8 0.6 0.4 0.2 0.0 No well with OWC in the training set well with OWC in the training set Relative importance Relative importance GR ResdiffPordiffSP RT NPHI RHO OWC RXO Resdiff GR PordiffRHO NPHI RXO RT OWC SP Feature Feature Halotel, McCarty, Gardiner, Demyanov, 2019, IAMG conference
Identify alternative scenarios Scenario A: prediction identical to true facies, similar to the ones by Dodd et al (2018) Scenario B: 4 combinations predict an alternative depositional scenario Halotel, McCarty, Gardiner, Demyanov, 2019, IAMG conference
How certain is the classifier? Entropya measure of diversity Sandstone with mudstone interbeds Hybrid Event Bed High 1.0 0.8 0.6 2460 0.4 0.2 Normalized entropy True facies Prediction scenario A Prediction scenario B 0.0 From Dodd et al (2018) From Dodd et al (2018) Low
Describe Variability and heterogeneity in subsurface models
The SOA Problem • Seismic imaging is limited by complex geological structures • State-of-the-art techniques are unable to produce a good image. ? Nathan Amaral, Heriot-Watt MSc thesis, 2019; Courtesy – Conoco Phillips
The Proposed Solution • PS images bring more information at SOAs. • PP images can be inferred from PS information with physics • Machine learning would be able to bypass physics limitations in the PP – PS problem Farfour and Yoon, 2016 Nathan Amaral, Heriot-Watt MSc thesis, 2019; Reidar
Generative Adversarial Networks (GANs) • Generator creates and discriminator classifies it • Adversarial training: similar to cop and counterfeiter https://skymind.ai/wiki/generative-adversarial-network-gan Goodfellow et al (2014)
A real mature field application • Seismic volume (length: 717, width: 1129) Nathan Amaral, Heriot-Watt MSc thesis, 2019; Courtesy ConocoPhillips
Flow Generator PS Boundary conditions Discriminator Encoder Bottleneck PP PS Decoder Classifies (real or fake) PP Backpropagate Real / Fake Nathan Amaral, Heriot-Watt MSc thesis, 2019
Optimization and training • Adversarial training: discriminator and generator loss fluctuates. Nathan Amaral, Heriot-Watt MSc thesis, 2019
Optimization and training • Competitive nature: the higher the discriminator loss, – the lower the generator loss (and vice-versa). Nathan Amaral, Heriot-Watt MSc thesis, 2019
Optimization and training • No network completely wins the competition, both get better at what they do (create or classify) Nathan Amaral, Heriot-Watt MSc thesis, 2019
Boundary conditions: results (test set) • Translates PS condition. • Respects boundaries. • Does not recover amplitudes. • Struggles with noise and complex geology (faults, strong dips, etc.). Nathan Amaral, Heriot-Watt MSc thesis, 2019
Blind test: SOA Nathan Amaral, Heriot-Watt MSc thesis, 2019
GAN PP SOA prediction Nathan Amaral, Heriot-Watt MSc thesis, 2019
What does GAN see? • Visualize layers to understand the process behind feature generation • Increases interpretability • May lead to an informed optimization of the network Nathan Amaral, Heriot-Watt MSc thesis, 2019
Outcomes Limitations • GAN is able to produce good quality PP images respecting the PS and boundary conditions on a real data • Main features and reflectors are preserved in the test samples, although an exact reproduction is not achieved • GAN model struggles in areas of more complex geology (faults, discontinuities, strong dips, etc.) • Unrealistic amplitudes as a result of upscaling • Blind test on SOAs had poor quality polluted with artifacts Nathan Amaral, Heriot-Watt MSc thesis, 2019
Predict Outcomes of subsurface resources development
Where are the remaining reserves? A real mature field challenge • 40 years of production with active aquifer support • Good reservoir quality • High heterogeneity • Densely drilled: hundreds of wells Relatively poorly understood geology • Poor quality data • Large geological uncertainty and heterogeneity Gas Oil Buckle, et al, ThPG06:, EAGE Petroleum Geostatistics, 2019Improving Local History Match Using Machine Learning Generated Regions from Production Response and Geological Parameter Correlations Water Buckle, et al, ThPG06:, EAGE Petroleum Geostatistics, 2019Improving Local History Match Using Machine Learning Generated Regions from Production Response and Geological Parameter Correlations
ML to guide the model update • Multiple models obtained from AI equipped history matching Large Remaining Reserves Small Buckle, et al, ThPG06:, EAGE Petroleum Geostatistics, 2019Improving Local History Match Using Machine Learning Generated Regions from Production Response and Geological Parameter Correlations
Correlation of causation? • Is the discovered zonation correlated with some meaningful geological feature? • What is possibly the cause? Buckle, et al, ThPG06:, EAGE Petroleum Geostatistics, 2019Improving Local History Match Using Machine Learning Generated Regions from Production Response and Geological Parameter Correlations
Correlation of causation? NTG in rock type 3 Depth to Carbonate Layer Buckle, et al, ThPG06:, EAGE Petroleum Geostatistics, 2019Improving Local History Match Using Machine Learning Generated Regions from Production Response and Geological Parameter Correlations
Predict remaining reserves with confidence Reserves confidence map Large Large oil accumulationgood match Large oil accumulationpoor match Remaining Reserves Small oil accumulationpoor match Small oil accumulationgood match Small Buckle, et al, ThPG06:, EAGE Petroleum Geostatistics, 2019Improving Local History Match Using Machine Learning Generated Regions from Production Response and Geological Parameter Correlations
Summary: added value from ML • Able to identify possible alternatives that impact reservoir decisions from the bulk of data • Tackle generative problem of obscure pattern reconstruction to improve interpretation • Help to introduce reservoir features that have been overlooked in the model to make better predictions
AI needs more explanatory power to become more interpretative to predict causation rather than correlation
Way Forward Current: Solution = ML expertise + data + computation Domain expert + Future: Solution = data + computation + auto search for best AI architecture after Jeff Dean, head of AI, Google
Vasily Demyanov v.demyanov@hw.ac.uk Thank you
A way to interpretable AI Introduce cognitive reasoning to AI DH Park, LA Hendricks, Z Akata, A Rohrbach, B Schiele, T Darrell, M Rohrbach, (2018) UC Berkley, U Amsterdam, Facebook AI
Acknowledgements North Falkland study Ekofisk study Vasily Demyanov (v.demyanov@hw.ac.uk)