Summary
The Jones (1981) steamflood model incorporates oil displacement by steam as
described by Myhill and Stegemeier (1978), and a three-component capture factor
based on empirical correlations. The main drawback of the model, however, is
the unsatisfactory prediction of the oil production peak: It is usually
significantly lower than the observed value. Our study focuses on improving
this aspect of the Jones model.
In our study, we simulated the production performance of a
five-spot-steamflood-pattern unit and compared the results against those based
on the Jones model (1981). To obtain a satisfactory match between simulation
and Jones-analytical-model results, at the start and height of the production
peak, the following refinements to the Jones model were necessary. First, the
dimensionless steam-zone size AcD was modified to account for the decrease in
oil viscosity during steamflood and its dependence on the steam injection rate.
Second, the dimensionless volume of displaced oil produced VoD was modified
from its square-root format to an exponential form. The modified model gave
very satisfactory results for production performance for up to 20 years of
simulated steamflood, compared to the original Jones model. Engineers will find
the modified model an improved and useful tool for the prediction of
steamflood-production performance.
Introduction
Steamflooding is a major enhanced-oil recovery (EOR) process applied to
heavy oil reservoirs. A steamflood typically proceeds through four development
phases: reservoir screening, pilot tests, fieldwide implementation, and
reservoir management (Hong 1994). Steamflood-performance prediction is
essential to provide information for the proper execution of each development
phase. Three mathematical models (statistical, numerical, and analytical
models) are often used to predict steamflood performance.
Statistical models are based on the historical data of steamflood
performance from other reservoirs which have similar oil and rock properties. A
statistical model, however, does not include all the flow parameters, and thus
may be inaccurate for a particular reservoir. Numerical models usually require
a large amount of data input with lengthy calculations using computers; and
they are usually CPU-, manpower- and time-consuming and also expensive. They
may be extremely comprehensive and better serve as tools for research or
advanced reservoir analysis. Meanwhile, analytical models are more economical,
but at the expense of accuracy and flexibility. They serve as tools for
engineering screening of possible reservoir candidates for field testing (Hong
1994).
For many years, attempts have been made to provide analytical models for
steamflood-production-performance prediction (Marx and Langenheim 1959; Boberg
1966; Mandl and Volek 1969; Neuman 1975; Myhill and Stegemeier 1978; Gomaa
1980; Jones 1981; van Lookeren 1977; Farouq Ali 1970; Miller and Leung 1985;
Rhee et al. 1978; Aydelotte et al. 1982). None of these analytical models gives
a comparison with simulation results. Miller and Leung (1985) presented
comparison between their analytical model and simulation results for cumulative
production vs time, but the comparison for production rate vs time is not
available.
© 2007. Society of Petroleum Engineers
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History
- Original manuscript received:
13 July 2005
- Meeting paper published:
1 November 2005
- Revised manuscript received:
2 April 2007
- Manuscript approved:
8 May 2007
- Version of record:
20 December 2007
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