Abstract:
Due to the excess heat loss of steam assisted gravity drainage (SAGD) processes
and low oil production rate of solvent-based processes, the expanding solvent SAGD
(ES-SAGD) process has been considered as a promising technique for enhancing heavy
oil/bitumen recovery. The main ES-SAGD mechanisms include the heat transferred and
dissolution of solvents into the heavy oil/bitumen to swell it and reduce its viscosity,
which is closely related to the phase behaviour of solvents-heavy oil/bitumen-water
systems. Thus, it is of fundamental and practical importance to accurately quantify the
phase behaviour and physical properties of the aforementioned systems.
A pragmatic technique has been developed to optimize the reduced temperature for
acentric factor for the Peng-Robinson equation of state (PR-EOS) and Soave-Redlich-
Kwong equation of state (SRK-EOS) by minimizing the deviation between the measured
and calculated vapour pressures. The reduced temperature has its optimum value of 0.59
for the two EOSs, while 0.60 is recommended for practical use.
The mutual solubility for n-alkanes/n-alkylbenzenes-water pairs is correlated using
the PR-EOS together with the two newly modified alpha functions. The binary
interaction parameters (BIPs) for both aqueous phase and liquid hydrocarbon phase are
generalized as functions of reduced temperatures and carbon numbers of hydrocarbons,
reproducing the experimental measurements well. Then, the modified PR-EOS model is
successfully applied to predict the multi-phase compositions and three-phase upper
critical ending points (UCEPs) for n-alkane-CO2-water mixtures.
A new correlation has been developed to calculate the redefined acentric factor for
pseudocomponents (PCs), while new BIP correlations are proposed respectively for
ii
toluene-water pair and heavy oil/bitumen-water pairs. The BIP correlation for heavy
oil/bitumen-water pairs is validated by the measured water solubility in other oils. The
newly developed model is found to accurately predict the measured ALV/AL (A is the
aqueous phase, L represents the oleic phase, and V denotes the vapour phase) and LV/L
boundaries with an overall average absolute relative deviation (AARD) of 4.5% and
solvent solubility in the oleic phase with an overall AARD of 9.4%, respectively.
Two new methods have been proposed to predict the density/swelling factor for
solvents-heavy oil/bitumen/water mixtures, i.e., one is a new volume translation (VT)
strategy for PR-EOS, while the other is the ideal mixing rule with effective density (IME)
calculated using a newly developed tangent-line method. It is found that both of these
two methods are accurate enough, while the IM-E is better than the VT PR-EOS.
Experiments for C3H8/CO2-Lloydminster heavy oil/water systems have been
performed in a temperature range of 328.7-432.3 K. A dynamic volume analysis method
is proposed to simultaneously simulate the total volume and height of vapour/oleic phase
interface, while a new framework incorporated with the modified PR-EOS can be used to
accurately predict the solvent solubility, phase boundary, and phase density for the
aforementioned systems. Also, six widely used mixing rules have been respectively
evaluated, while water is incorporated using the ideal mixing rule. The order of the best
ones in their accuracy is the volume-based power law > the weight-based power law >
the weight-based Cragoe’s mixing rule. The effective density rather than real density of
dissolved gas should be used for all the volume-based mixing rules.
Description:
A Thesis Submitted to the Faculty of Graduate Studies and Research In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Petroleum Systems Engineering, University of Regina. xxxiii, 313 p.