Enhanced gas production efficiency of class 1,2,3 hydrate reservoirs using hydraulic fracturing technique

Abstract

Current gas hydrate production test indicates that it is difficult to reach the commercial level for low permeability hydrate-bearing formation by depressurization method. Hydraulic fracturing in hydrate-bearing sediments (HBS) is a promising method to enhance gas production efficiency. In this study, the use of hydraulic fracturing and depressurization method to improve the recovery rate for class 1,2,3 hydrate reservoirs is studied. The three-dimensional large-scale HBS simulation model is firstly established with the single bi-wing vertical fracture. The gas production behavior for cases with different fracture parameters is investigated including the fracture conductivity, position, scale, and length. The simulation results show that fracture parameters have significant influence on Class 2 and Class 3 hydrate reservoirs. By enlarging the fracture conductivity, fracture length, and fracture scale, the flow resistance around the well can remarkably decrease which is beneficial to the pressure spread and hydrate dissociation. The peak rate of gas production increases and the peak time arrives early. The production feature is analyzed based on the test data in Shenhu Area of the South China Sea (SCS) by numerical simulation method. The cumulative gas production substantially increases by using hydraulic fracturing technique compared to that without fracturing.