Gas production from hydrate reservoir by the combination of warm water flooding and depressurization is proposed, which can overcome the deficiency of single production method. Based on the combination production method, the physical and mathematical models are developed to simulate the hydrate dissociation. The mathematical model can be used to analyze the effects of the flow of multiphase fluid, the kinetic process of hydrate dissociation, the endothermic process of hydrate dissociation, ice-water phase equilibrium, the convection and conduction on the hydrate dissociation and gas and water production. The mechanism of gas production by the combination of warm water flooding and depressurization is revealed by the numerical simulation. The evolutions of such physical variables as pressure, temperature, saturations and gas and water rates are analyzed. Numerical results show that under certain conditions the combination method has the advantage of longer stable period of high gas rate than the single producing method. natural gas hydrate reservoir, warm water flooding, depressurization, numerical simulation Citation:Bai Y H, Li Q P. Simulation of gas production from hydrate reservoir by the combination of warm water flooding and depressurization.

In oil and gas exploration and transportation, low dosage hydrate inhibitors (LDHIs) are more favorably utilized to inhibit the formation of hydrates than thermodynamic inhibitors (THs) as a trend. However, there are no industrial products of LDHIs available domestically, and the corresponding application experience is in urgent need. In this paper, a combined hydrate inhibitor (HY-1) was synthesized after a series of reaction condition optimization, and its performance on THF hydrate inhibition was investigated using kinetic hydrate inhibitor evaluation apparatus with 6 cells bathing in air. The results show that when the reaction temperature is 60°C, the reaction time is 6 h, and the monomer: solvent ratio is 1:2, the product has the best kinetic hydrate inhibitor performance on THF hydrate. On these bases, the scale-up production of this combined hydrate inhibitor was carried out. Although the scale-up product (HY-10) performs less effectively on the THF hydrate inhibition than HY-1, it functions better than a commercial product (Inhibex501) during in-house tests. HY-10 was successfully applied to the gas production process. Field trials in northern Shaanxi PetroChina Changqing Oilfield Company (PCOC) show that 2 wt% of HY-10 is effective on natural gas hydrate inhibition. It is found through economic analysis that the use of HY-10 has obvious economical advantage over methanol and Inhibex501. natural gas hydrate, combined hydrate inhibitor, kinetic hydrate inhibitors, natural gas production Citation:Hu J, Wang Y H, Lang X M, et al. Synthesis and application of a novel combined kinetic hydrate inhibitor.

The vast amount of hydrocarbon gas encaged in gas hydrates is regarded as a kind of future potential energy supply due to its wide deposition and cleanness. How to exploit gas hydrate with safe, effective and economical methods is being pursued. In this paper, a mathematical model is developed to simulate the hydrate dissociation by depressurization in hydrate-bearing porous medium. The model can be used to analyze the effects of the flow of multiphase fluids, the intrinsic kinetic process of hydrate dissociation, the endothermic process of hydrate dissociation, ice-water phase equilibrium, the variation of permeability, the convection and conduction on the hydrate dissociation and gas and water production. The numerical results agreed well with the 1-D and 2-D experiments. The numerical results for 3-D hydrate reservoir show that in the first stage of depressurization gas can be produced effectively from hydrate reservoir. With the depletion of reservoir energy because of endothermic process of hydrate dissociation the gas rate decreases rapidly. Then, methods such as thermal stimulation and inhibitor injection should be considered to replace depressurization. depressurization, gas hydrate reservoir, numerical simulation, physical experiment

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This paper presents a detailed characterization and modeling of 6.5kv SiC MOSFET half-bridge module. Based on the equivalent circuit topology, the model parameters are extracted from the data manual and test data, and the behavior model is constructed to describe the static and dynamic characteristics of the device. This paper used behavioral model functions, and carries out parameter extraction and model fitting for new devices. The model is verified by double pulse test under inductive load. The verification results show that the modeling work is correct and effective, it can predict the switching performance of devices in high voltage applications.