Unlocking the deepwater natural gas hydrate's commercial potential with extended reach wells from shallow water: Review and an innovative method

Deepwater natural gas hydrate (NGH) is generally accepted as a promising energy source for humanity in the coming future due to its huge amount of available reserves on earth. However, as deepwater NGH reservoirs always have restricted accessibility, harsh engineering conditions and high operation risk, their development has been considered technically and economically less viable. Worldwide field production tests have indicated that the current techniques are not able to commercially develop deepwater NGH independently. Therefore, technological revolutions for deepwater NGH development is pressing to unlock deepwater NGH's commercial potential. The purpose of this work is twofold. First, the state-of-art research on the NGH reservoirs development and extended reach wells (ERWs) technology are comprehensively reviewed. In addition to summarize the previous research achievements, the limitations and insightful suggestions are put forward for future deepwater NGH development. Second, inspired by the development of ERWs technology and its great success in maximum depletion of the offshore unconventional oil & gas reservoirs, an innovative method for unlocking the deepwater NGH's commercial potential with ERWs from shallow water is proposed. With the benefits of improving the deepwater NGH reservoirs drainage, taking full advantage of the formation geothermal heat beneath shallow water, combining depressurization with the thermal simulation technique though linking the deepwater NGH reservoirs with multiple free gas deposits in shallower water with a single wellbore, getting free of engineering and geological risks in deepwater, minimizing the cost and environmental footprint, the innovative method may promote the commercial viability of deepwater NGH development and trigger the next boom in the unconventional oil & gas development after shale gas.