Geological Risks & Uncertainty
. . . We can help  in early stages of exploration especially in Frontier basins

DEFINITIONS

Need to understand some key terms in managing risk and uncertainties in exploration.

 

UNCERTAINTY

It is a spectrum, or a range of outcomes. Uncertainty includes successful and unsuccessful outcomes (risk is included as special subclass).

RISK

Risk is chance of discrete outcome; a failure or unsuccessful event.

LEVEL OF KNOWLEDGE

Capturing Range of Uncertainty - Level of Knowledge (LOK)

  1. What we know

  2. What we know we don't know

  3. What we don't know we don't know

Our LOK will impact our ability to quantify risk and uncertainties. We need to differentiate between 'known risk' and 'remaining uncertainty.' This also distinguishes between 'reducible' and 'irreducible' risk.

MODEL VS PARAMETER UNCERTAINTY

In early stages of exploration (especially 'frontier' basins) there is a lack of data and knowledge, therefore there is a considerable uncertainty in possible geological models and geological/petrophysical parameter associated with it. Therefore a clear distinction must be made in between 'model uncertainty' and 'parameter uncertainty.'

 

Generally, large Integrated multinational oil companies have their own softwares to mange model uncertainties, on the other hand parameter uncertainty can be handled using Monte-Carlo situation method using commercial software (example: CrystalBall)

  1. Model Uncertainty

    • Oil prone vs gas prone

    • Reservoir facies type (Clastic vs carbonate)

    • Fault Capacity (Sealing vs leaking)

  2. Parameter uncertainty

  • Expected range in porosity , NtG and saturation

  • Spill-point depth

  • Oil density

This is especially relevant in risking and volumetric; each 'model' should be run separately with its own set of 'parameter' uncertainty and not be mixed with parameters of a different model.

GENERAL GUIDANCE FOR QUANTIFICATION OF GEOLOGICAL RISKS & UNCERTAINTIES

The 'Adequacy Matrix,' is one way that used to quantify risk and uncertainty. 9see figure below). It is based on two parameters:

  1. Degree of Confidence

    • Degree of confidence depends on LOK, i.e. quantity AND quality of available data

    • It may range from High (good quality conclusive data) to Moderate to Low (for quality non-conclusive data) mostly relying on analogues.

  2. Risk Severity

    • Risk severity is controlled by whether we see "positive' or 'negative' indications.

    • Severity also ranges from High -> Moderate -> Low 

Maps (see Fig) are generated per play element (chance factors)and overall play risk may also displayed.  

 

The 'Degree of Confidence' and ' Severity of risk,' must be included for following elements:

  1. Structure

  2. Seal 

  3. Reservoir

  4. Charge

  5. Hydrocarbon Properties

  6. Fluid type

Contact us, we can help you with Degree of Confidence and Risk Severity in each play element and mapping

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