Page 103 - Primer on Enhanced Oil Recovery

Ternary diagrams and miscible displacements 93

The above model is a simplification. Majority of real displacement drives with
carbon dioxide and enriched gas have both processes. Only processes during injection
of dry hydrocarbons, nitrogen and flue gases are proceed by vaporizing scenario.
One of the areas where ternary diagrams are used extensively is the description
(analysis) of reservoir oil behavior during various liquids and gasses injection into
the reservoir. It is complicated area in oil extraction with many variables and pro-
cesses. We will only introduce the topic here and then provide few more examples
later in the book.
The vaporizing mixing can be analyzed as presented on Fig. 9.6. Injected gas
(liquid) is going to mix with oil. At the initial mixing the mixture has the composi-
tion M1.This composition will separate on vapor (V) and liquid (L). The line con-
necting those states is named a tie or a connode. The vapor now contains more
intermediate hydrocarbons. The vapor spreads through the reservoir faster than the
liquid. Vapor again mixes with oil and created composition M2. The process with
separation is repeated again, the vapor will get the mixture M3 and eventually will
a to a critical point composition and will become a single phase miscible liquid.
We will discuss more specific examples in Chapter 10.