Enhancement of Gas Production from Class 1-Type Hydrate Reservoirs with High-Pressure Rotating Water Jets in Horizontal Well Depressurization Production

Reservoir stimulation technology is important for improving the gas production efficiency of natural gas hydrate exploitation. Based on the data of the first natural gas hydrate field test in the Shenhu Sea area, the gas production capability of Class 1-type hydrate reservoirs was numerically evaluated by horizontal well depressurization with high-pressure rotating water jets (HPRWJ). The results showed that the HPRWJ can effectively improve the production efficiency. The mechanism is enlarging the drainage area and improving the seepage conditions of the reservoir. With the wellbore deployed at the middle part of the three-phase layer, compared with the unstimulation case, the case with HPRWJ results in the V g increased by 140.65% after 1080 days of production with a length of 300 m and the stimulation parameters: Q (quantity), R (radius), S (spacing), W (width), K (permeability), and P (porosity) were set to 25, 5.5 m, 11.5 m, 0.5 m, 5 D, and 0.7, respectively. With comprehensive parameter analysis, the results show that the stimulation zone quantity and radius are the main control parameters for improving production efficiency, and the permeability and porosity had less effect. It is suggested to use low density with a large radius when adopting HPRWJ, which can save construction time and costs.