Expressing reduction of uncertainty

The most informative method of expressing uncertainty in HCIIP or ultimate recovery (UR) is by use of the expectation curve, as introduced in Section 6.2. The high (H) medium (M) and low (L) values can be read from the expectation curve. A mathematical representation of the uncertainty n a parameter (e.g. STOMP) can be defined as 

The stated objective of appraisal activity is to reduce uncertainty. The impact of appraisal on uncertainty can be shown on an expectation curve, if an outcome is assumed from the appraisal. The following illustrates this process. 

Suppose that four wells have been drilled in a field, and the geologist has identified three possible top sands maps based on the data available. These maps, along with the ranges of data for the other input parameters (N/G, S, cj), B ) have been used to generate an expectation curve for STOMP. 

If well A is oil bearing, then the low case must increase, though the high case may not be affected. If well A is water bearing (dry), then the medium and high cases must reduce, though the low case may remain the same. For both outcomes, the post-appraisal expectation curve becomes steeper, and the range of uncertainty is reduced. 

Note that it is not the objective of the appraisal well to find more oil, but to reduce the range of uncertainty in the estimate of STOMP. Well A being dry does not imply that it is an unsuccessful appraisal well. 

---