Oil and Gas

Participants will learn to:

1. Form a fluid-sensitive conceptual model for a heterogeneous reservoir, built from a selection of elements and placed in a realistic architectural framework: ‘the sketch’.
2. Evaluate which rock modelling algorithms to select in order to digitally realise the desired architectural concept.
3. Explore an intuitively-guided use of geostatistical tools, balancing deterministic and probabilistic components and with awareness of the limits of the tools.
4. Select appropriate methods for property modelling, including the handling of ‘net’ (cut-offs vs. total property modelling) and the handling of porosity and saturation.
5. Understand the issues surrounding permeability modelling and why this differs from the handling of other properties.
6. Understand standard options for upscaling of properties, both for single phase and multi-phase systems.
7. Explore options for multi-scale modelling and determine the need for multi-scale approaches based on a hierarchical understanding of (REV) Representative Elementary Volumes.
8. Review options for model-based uncertainty-handling (base-case led, multi-deterministic, multi-stochastic), and how to select an appropriate workflow which minimises the impact of behavioural heuristics and biases.
9. Complete a reservoir model design for a synthetic field case, fit-for-purpose and ready for input to a dynamic reservoir engineering simulation.

The central theme of the event is Reservoir Model Design, on the premise that it is design rather than software knowledge that typically distinguishes ‘good models’ from ‘bad models’. This is organised around the following five themes, issues within which are often the cause of a poor model outcome:

1. Model purpose – why are we logged on in the first place and what is the question we are specifically trying to address? The size and scaling of the model and the statistical handling of raw data differ depending on the ultimate model purpose.
   
2. Elements and architecture – how much detail should be incorporated in the models? From the rich spectrum of potential lithofacies, electrofacies, biostratigraphic and analogue data inputs, how do we select the ‘right’ number of components (elements) to take forward into the modelling process? Once selected, how do these elements combine into a realistic description of length scales and reservoir architecture? Indeed, is there a clear, fluid-sensitive reservoir concept at all; can it be sketched?
   
3. Probability and determinism – is the balance of probabilistic and deterministic components appropriate given the model purpose? Should heterogeneities be handled implicitly or explicitly in the static and dynamic models? What are our expectations of geostatistics and how do we control the algorithms intuitively to replicate a reservoir concept?
   
4. Multi-scale modelling – what scale should we be modelling and simulating at given the fluid type and model purpose? Can everything be modelled at one scale, or are static/dynamic multi-scale models required? We address the full spectrum of heterogeneity using the concept of Representative Elementary Volumes and conclude that traditional static-dynamic upscaling is only part of the story, and not always the main part.
   
5. Model-based uncertainty-handling – how to really go wrong. What are the tools we can use to identify natural bias in the modelling process and select workflows which capture useful ranges in a practical way, minimising bias in the process. We summarise the current range of stochastically- and deterministically-led options, and discuss which is appropriate to use, and when.

Location and Itinerary:

The course is based in Saundersfoot, an excellent venue well-situated for easy access to a wide range of analogue reservoir outcrops. Field locations include Amroth, Manorbier, Freshwater, and Saundersfoot itself. At least one location will be visited each day, with each day starting and finishing in the classroom. Exact timings will depend on tide times and weather. The itinerary and content can also be flexible to meet the interest areas of the group.

Day 0: Pick up from Heathrow and road transfer to Wales (typically 4 hours)

Day 1: Model purpose, elements and architecture

Day 2: Rock modelling, probability and determinism, practical geostatistics

Day 3: Property modelling, handling permeability and fractures

Day 4: Dealing with scale: upscaling, multi-scale modelling and the REV

Day 5: Model-based uncertainty handling; completing the Pembroke model design and debriefing with reservoir and simulation models.

Day 6: Return to Heathrow and departure

Geoscientists with some knowledge of reservoir modelling; Petrophysicists who provide input to static reservoir models; Reservoir engineers involved in simulation work who deal with the static-dynamic interface and upscaling on a regular basis. Multidisciplinary asset teams would benefit from attendance as a group. The course is also of benefit to team leaders who wish to have a deeper understanding of the principles behind modelling, and any subsurface staff involved in the QC of models made by others.