Page 186 - Fundamentals of Enhanced Oil and Gas Recovery

174 Forough Ameli et al.

Figure 5.12 Advancement of the heated zone in the reservoir.

Overall heat loss from wellbore:
_
Q lwb 5 2πr to U to T s 2 T h ÞL
ð
5 2π 0:146Þ 3:14Þ 600 2 364Þð3000Þ
ð
ð
ð
5 2040; 000 Btu=h
5.2.11 Reservoir Heating by Steam Injection Using
Marx Langenheim Model
By heating the reservoir, a considerable amount of energy is lost to the formation. The
modeling procedure for reservoir was introduced by Marx Langenheim [70] in which
the rock and fluid properties are considered constant. The distribution of steam is verti-
cal in the selected region which leads to constant temperature in vertical direction. No
segregation of condensate and steam occurs. The advancement of the heated zone in
the reservoir is characterized by step function, as depicted in Fig. 5.12A and B.
• This process which carries a part of oil, gas, or water through the reservoir also carries heat.
• The mechanisms of heat transfer include conduction and convection. This is the
case also for the displaced fluids
• For nonmoving fluids, the mechanism of heat transfer is conduction. This leads to
equality of fluid and solid temperature.
• Determinative parameter to reach the equilibrium is heat transfer coefficients.
• As heat conduction occurs in surrounding sands, the heated sand area considering
o/u is greater than that of invaded area by steam.
• The speed of heat front is less than the transferred heat by any injection
mechanism.

5.2.11.1 The Assumptions of Marx Langenheim Model
1. The temperature through the reservoir has a constant value of T s .
2. The reservoir thickness is uniform.