addressing uncertainty in oil and natural gas industry greenhouse

5.0 UNCERTAINTY CALCULATION EXAMPLES
5.1 Introduction
The section demonstrates the concepts provided in
Section 4.0 through examples taken directly from the
2009 API Compendium of Greenhouse Gas Emissions
Estimation Methodologies for the Oil and Gas Industry
(API Compendium, 2009). Each of the examples
represents a hypothetical situation rather than any
particular actual facility or operation. The facility
example is based on a GHG inventory from an “Onshore
Field with High CO 2 Content,” as described in Section
8.1.1 of the API Compendium. The uncertainties
associated with vented emissions from refinery catalytic
cracking units and hydrogen plants are based on
methodologies and examples presented in Sections 5.2.1
and 5.2.2 of the API Compendium, respectively. Details
on the source-by-source uncertainty calculations are
provided in Appendix F. Highlighted text in this section
is used to designate uncertainty calculations.
Section Focus
This section combines the guidelines,
procedures, and equations for calculating
uncertainty that were outlined in Section 4 and
applies them to a hypothetical facility to
calculate total uncertainty for the facility-level
GHG inventory. The statistical approaches are
also applied to two select refinery operations
to examine and compare uncertainty estimates
for different emission estimation
methodologies.
This section will not describe how the
inventory was generated or calculated. For
that background, the reader is referred to the
API Compendium (API, 2009). Much of the
emission calculation information is simply
reprinted directly from the API Compendium
without elaboration in this report.
This section will describe how uncertainties
are assigned to each value in the inventory and
then propagated to a single overall uncertainty
associated with the total summed inventory for
the facility.
5.2 Example 1: Onshore Oil Field with High CO 2 Content
5.2.1 Background
Tables 5-1 and 5-2 summarize the emission sources and uncertainty values associated with this facility.
This example field is described in detail in the API Compendium, but is summarized here for context. A
discussion of the uncertainty values associated with the example facility parameters follows.
Pilot Version, September 2009 5-1