Business context
A decision to drill an exploration well with the objective to find a new oil or gas field must be based on a sound assessment of the prospect risk and of the volumes: what is the chance that a well will find hydrocarbons, and how much could it be? Risk and volume assessments form the basis for decisions to drill a well or not, and as such form the link between subsurface evaluation and the business aspects of the petroleum industry. This course explains how risks and volumes can be assessed in a realistic manner, based on a sound understanding of the geological details of the prospect as well as of its regional geological setting and current play understanding.
Who should attend
This course is designed in the first place for geoscientists working in exploration, for prospect portfolio analysts and for their direct supervisors. It is also a very instructive course for staff from disciplines working closely with exploration staff, such as reservoir engineers, petrophysicists and geophysicists.
Course content
The course will demonstrate that realistic risk and volume assessment is not a "black box" operation, but needs geological understanding of the prospect, and the regional setting.
Specific topics that will be discussed include:
Learning, methods and tools
The VILT will be delivered online in5 sessions of 3 hours per day, with 2 breaks of 10 minutes per day. It is the intention to have at least 2 smaller exercises per day. Time will be reserved for recapitulation, questions and discussions.
VILT will be conducted either via Zoom or Microsoft Teams. Presenting materials can easily be done on this platform. When participants need to ask a question, they can raise their hand, write notes or interrupt the Instructor by using their microphone. The presenter can switch to a screen where he/she can see all participants (also when each participant is sitting in another location e.g. at home).
Each topic is introduced by a lecture, and learning is re-enforced by practical exercises and discussions. Hand-out material in paper and/or electronic format will be provided.
Day by day programme
DAY 1: Risks, Volumes and Uncertainty
Introduction participants and course instructor
Introduction
An outline of the programme and the objective of the course.
Introduction to Risk & Volume assessment: the main concepts and discussion of how the results of risk & volume assessments are used in the business
Risks, Volumes and Uncertainty
The difference between risk and uncertainty, basics of essential statistical concepts, the play elements and workflow to assess prospect risks, biases in estimating uncertainties, the results of probabilistic volume assessments and their representation in expectation curves and frequency plots, exercises to enhance understanding of introduced concepts
Prospects and Plays
Demonstration of how understanding of the regional geology, petroleum systems and hydrocarbon plays is an essential element in the assessment of risks & volumes for individual prospects; exercise on the use of play maps as aid in risk assessment
DAY 2: The Risk Elements: Traps and Reservoirs
Summary of Day 1
Re-cap of main learning points
Traps
Risks and uncertainties associated with hydrocarbon traps, the difference between spill and leak points, how to deal with sealing faults and overpressures, what are the risks of stratigraphic traps, how to estimate realistic uncertainty ranges for hydrocarbon column length, exercises
Reservoirs
Risks and uncertainties associated with reservoir rocks, how to deal with layered reservoirs, waste zones and irregularly shaped reservoirs, facies and depth trends in reservoir characteristics, exercises
DAY 3: The Risk Elements: Seals and Charge
Summary of Day 2
Re-cap of main learning points
Seals
Mechanisms of seal failure, how to deal with leaky seals and differential leakage of gas, overpressures and impact on seal risk and column length prediction, exercises to enhance understanding
Charge
Impact of source rock types and timing issues for charge assessment, how to deal with mixed columns (oil and gas), formation volume factors (gas expansion and oil shrinkage), hydrocarbon saturations and recovery factors, the impact of long transition zones in tight reservoir rocks
DAY 4: Risk and Volume assessment in practice
Summary of Day 3
Re-cap of main learning points
Risk assessment
Practical exercise in small break-out groups on prospect risk assessment, group discussion on the impact of positive and/or negative geological indications for the presence or absence of play elements
Exercise and discussion: Determining the Chance Factors for a prospect
Volume assessment
Practical back-of-the-envelope volume calculation exercise, how to quickly calculate low, medium and high volumes for a prospect, recapitulation of how to select appropriate distributions
DAY 5: Bringing it all together
Summary of Day 4
Re-cap of main learning points
Volumes and portfolios
The impact of dependencies between prospects in a portfolio, risking and volume assessment of prospects with stacked reservoir-seal pairs, adding probabilistic prospect volumes statistically correct
Exercise: determining dependency between prospects
Geophysical evidence
The impact on prospect POS (probability of success) of direct hydrocarbon indicators (DHIs) and/or positive (or negative) evidence form controlled source electromagnetics (CSEM) - consistent with Bayes' theorem
Exercise: Calculating an updated POS based on geophysical evidence
Look-back studies
The only way to improve prospect predictions is by comparing our past predictions with actual well results. It will be shown how we can we best do this, and common industry trends will be discussed.
Course Close-out