Study on the Separation Technology of HGS and Its Effect
141
and c. s. Kabir [9] basically contained important factors that needed to be considered,
so the adaptation situation of this model was relatively broad, however, its disadvantage
was that it relied on more parameter conditions, which made the calculation more complicated. Based on the first law of thermodynamics and the modified Raymond, Yang M
et al. [10] developed a more concise wellbore temperature calculation model, the results
shown that the heat transfer at the connection of the drill string or the casing shoe had
a great influence on wellbore temperature. Ramey [11] calculated wellbore temperature under transient and steady-state conditions under the assumption that drilling fluid
was single-phase flow. The operating condition of the wellbore temperature calculation
model established by Holmes Swift’s [12] was that only with a relatively long circulation
time could certain accuracy be guaranteed. The wellbore temperature calculation model
established by Garcia and Chen YH [13, 14] did not take into account the heat generated
by flow friction during the circulation process of drilling fluid flow, and ignored the constant variation of the thermal and physical properties of drilling fluid with temperature
and pressure, which obviously did not conform to the actual drilling situation, resulting
in a large error in the calculation. In order to simplified the calculation process without
affecting the calculation accuracy, Marshall Bentsen [15] finally established a mathematical model for calculating wellbore temperature by using the integrated convective heat
transfer coefficient. Based on two-phase flow model, Li MB et al. [16, 17] established
the transient heat transfer equation under the condition of considering the influence of
eccentric rotation of drill string on wellbore temperature, and made sensitivity analysis
on the key factors affecting temperature and pressure as well as wellbore temperature
calculation of the HTHP well. Garcia et al. [13] established the variation of wellbore
temperature under complex conditions, such as wellbore overflow or leakage, and the
shut-in condition, and made a detailed analysis of temperature distribution under different conditions. Espinosa et al. [18] established the wellbore temperature distribution
during the process of drilling circulation and the condition of suspending drilling, and
studied the variation relationship between operating parameters and temperature profile
in the two situations, which provided an important reference for the construction operations during the process of drilling circulation and stopping. Yang M et al. [19, 20] made
a comprehensive comparison and analysis of the distribution of wellbore temperature
in the axial and radial direction, and concluded that the axial heat conduction could be
neglected in the calculation of wellbore temperature. In addition, a new transient heat
transfer calculation model is established based on the composition of drill string and the
structure of well depth. Zhang Z et al. [21–23] took into account the distribution characteristics of wellbore temperature profile when leakage occurs in bottom-hole, and located
the leakage position through the characteristics of the annulus temperature distribution.
What’s more, the key factors affecting wellbore temperature in horizontal Wells are
studied, and the annulus temperature profile after shut-in is analyzed. Yang HW et al.
[24, 25] established the transient heat transfer model for controlled gradient drilling.
Although the model analyzes the effect of injecting HGS on wellbore temperature, the
calculation model does not verify the separation efficiency, but only assumes that it is a
constant value. Moreover, the effects of separation efficiency and injection rate on mass
and heat transfer were not considered, which obviously did not accord with the actual
situation in double-gradient drilling. At the same time, the transient heat transfer model
141
and c. s. Kabir [9] basically contained important factors that needed to be considered,
so the adaptation situation of this model was relatively broad, however, its disadvantage
was that it relied on more parameter conditions, which made the calculation more complicated. Based on the first law of thermodynamics and the modified Raymond, Yang M
et al. [10] developed a more concise wellbore temperature calculation model, the results
shown that the heat transfer at the connection of the drill string or the casing shoe had
a great influence on wellbore temperature. Ramey [11] calculated wellbore temperature under transient and steady-state conditions under the assumption that drilling fluid
was single-phase flow. The operating condition of the wellbore temperature calculation
model established by Holmes Swift’s [12] was that only with a relatively long circulation
time could certain accuracy be guaranteed. The wellbore temperature calculation model
established by Garcia and Chen YH [13, 14] did not take into account the heat generated
by flow friction during the circulation process of drilling fluid flow, and ignored the constant variation of the thermal and physical properties of drilling fluid with temperature
and pressure, which obviously did not conform to the actual drilling situation, resulting
in a large error in the calculation. In order to simplified the calculation process without
affecting the calculation accuracy, Marshall Bentsen [15] finally established a mathematical model for calculating wellbore temperature by using the integrated convective heat
transfer coefficient. Based on two-phase flow model, Li MB et al. [16, 17] established
the transient heat transfer equation under the condition of considering the influence of
eccentric rotation of drill string on wellbore temperature, and made sensitivity analysis
on the key factors affecting temperature and pressure as well as wellbore temperature
calculation of the HTHP well. Garcia et al. [13] established the variation of wellbore
temperature under complex conditions, such as wellbore overflow or leakage, and the
shut-in condition, and made a detailed analysis of temperature distribution under different conditions. Espinosa et al. [18] established the wellbore temperature distribution
during the process of drilling circulation and the condition of suspending drilling, and
studied the variation relationship between operating parameters and temperature profile
in the two situations, which provided an important reference for the construction operations during the process of drilling circulation and stopping. Yang M et al. [19, 20] made
a comprehensive comparison and analysis of the distribution of wellbore temperature
in the axial and radial direction, and concluded that the axial heat conduction could be
neglected in the calculation of wellbore temperature. In addition, a new transient heat
transfer calculation model is established based on the composition of drill string and the
structure of well depth. Zhang Z et al. [21–23] took into account the distribution characteristics of wellbore temperature profile when leakage occurs in bottom-hole, and located
the leakage position through the characteristics of the annulus temperature distribution.
What’s more, the key factors affecting wellbore temperature in horizontal Wells are
studied, and the annulus temperature profile after shut-in is analyzed. Yang HW et al.
[24, 25] established the transient heat transfer model for controlled gradient drilling.
Although the model analyzes the effect of injecting HGS on wellbore temperature, the
calculation model does not verify the separation efficiency, but only assumes that it is a
constant value. Moreover, the effects of separation efficiency and injection rate on mass
and heat transfer were not considered, which obviously did not accord with the actual
situation in double-gradient drilling. At the same time, the transient heat transfer model