Research On Well Pattern Of Natural Gas Hydrate Depressurization Exploitation

Energy is the key point of the development of human society.With the reduction of traditional energy,it is urgent to find new energy for the future development.After the investigation done by researchers from all over the world,it is confirmed that the quantity of natural gas hydrate in the nature is huge,and it is much cleaner than traditional energy after burnt,which is known as the future strategic energy.However,because the gas hydrate reservoir is mostly composed of porous media,the mining area influenced by single well is small.Then how to arrange the wells reasonably and scientifically has become the focus of research.Based on the previous research about well pattern of natural gas hydrate exploitation,this paper proposed a more detailed and reliable rule for arranging the wells.Though the grid division of the hydrate exploitation area,the study of well pattern was carried out under the consideration of the similarity of spatial locations.During the simulation,A total of 12 single-well and 82 double-well arrangement schemes were proposed by dividing 2×2 meshes,3×3 meshes,4×4 meshes and,5×5 meshes in the hydrate exploitation area,and simulated on TOUGH+HYDRATE software platform.After the simulation,the different exploitation schemes were analyzed and compared with evaluation criterions,such as gas recovery velocity,the cumulative gas volume,natural gas recovery ratio,gas-water ratio.In the process of the double-well pattern research,when the 2 wells located on the diagonal of the hydrate exploitation area and were symmetrical of the central point,the exploitation performance was better.The cumulative gas volume increased firstly then decreased while the position of the two wells moved gradually from the two ends of the diagonal of the square exploitation area to the center point and was symmetrical all the time.And the total amount of cumulative gas volume was the most when the wells moved to the position which was about 3.37 meters away from the center.In the process of depressurization exploitation with single vertical well,the exploitation and economic performance were best when the well located in the center of the hydrate exploitation area.The performance became worse while the distance between the well and the boundary of hydrate exploitation area reduced gradually.The gas-water ratio of all the double-well arrangement schemes was smaller than that of the best single-well arrangement scheme.When the 2 wells of the double-well arrangement schemes were closer to the boundary of hydrate exploitation area,their exploitation performance was worse than that of the best single-well arrangement scheme.