Investigation on the Secondary Generation of Natural Gas Hydrates in Horizontal Wellbore Caused by Pressure Jump during the Depressurization Development of Hydrate Bearing Layers

Table 2

Basic parameters.

Basic parameters	Value	Basic parameters	Value
Horizontal section length, m	500	Wellhead environment temperature, °C	25
Submarine environment temperature, °C	5	Submarine section length, m	800
Horizontal well burial depth, m	1,000	Deflecting section length, m	150
Sea temperature gradient, °C/100 m	-2.5	Formation temperature gradient, °C/100 m	3
Gas output index, kg/(MPa·m·s)	0.0001	Water output index, kg/(MPa·m·s)	0.001
Hydrate reservoir pressure, MPa	10	Thermal conductivity of formation, W/m/°C	3.92
Radius of tubing, m	0.05	Tubing thickness, m	0.01
Radius of casing, m	0.1	Casing thickness, m	0.01
Radius of cement sheath, m	0.15	Cement sheath thickness, m	0.05
Thermal conductivity of cement, W/m/°C	19.4	Thermal conductivity of casing and tubing, W/m/°C	45
Hydrate formation rate, mole/(MPa·s·m^2)		Hydrate dissociation rate, mole/(Pa·s·m^2)
Activation energy, J/mole	81084.2	Reaction enthalpy, J/mole	51858