Ning Zhengfu

Experimental and modeling study of kinetics for methane hydrate formation with tetrahydrofuran as promoter

The kinetics behavior of methane hydrate formation in the presence of tetrahydrofuran (THF) as promoter was studied. A set of experimental equipment was designed and constructed. A series of kinetics data for the formation of methane hydrate in the presence of THF were measured with the isochoric method. The influences of temperature, pressure and liquid flow rate on the methane consumption rate were studied respectively. Based on the Chen-Guo hydrate formation mechanism, a kinetics model for the formation of methane hydrate in the presence of THF by using the dimensionless Gibbs free energy difference of quasi-chemical reaction of basic hydrate formation, — δG/RT as the driving force was proposed. The model was used to calculate the rate of methane consumption and it was shown that the calculated results were in good agreement with the experimental results.

Steam flooding after steam soak in heavy oil reservoirs through extended-reach horizontal wells

This paper presents a new development scheme of simultaneous injection and production in a single horizontal well drilled for developing small block reservoirs or offshore reservoirs. It is possible to set special packers within the long completion horizontal interval to establish an injection zone and a production zone. This method can also be used in steam flooding after steam soak through a horizontal well. Simulation results showed that it was desirable to start steam flooding after six steam soaking cycles and at this time the oil/steam ratio was 0.25 and oil recovery efficiency was 23.48%. Steam flooding performance was affected by separation interval and steam injection rate. Reservoir numerical simulation indicated that maximum oil recovery would be achieved at a separation section of 40–50 m at steam injection rate of 100–180 t/d; and the larger the steam injection rate, the greater the water cut and pressure difference between injection zone and production zone. A steam injection rate of 120 t/d was suitable for steam flooding under practical injection-production conditions. All the results could be useful for the guidance of steam flooding projects.