Sand Production Management During Marine Natural Gas Hydrate Exploitation: Review And An Innovative Solution

Natural gas hydrate (NGH) is widely distributed worldwide with great reserves and is generally accepted as a promising alternative energy source. However, sustainable, efficient, and safe NGH development has been proven to be restricted by a series of geomechanical problems, among which sand production has become prominent and attention-catching. This review systematically summarizes the up-to-date literatures and reports our latest work to improve the fundamental understandings of the sand production issues in NGH development. It is noted that sand production is defined as a systematic "issue", rather than a "problem" in this paper, considering both the adverse and favorable influences of sand production on continuous gas production from hydrate-bearing sediment (HBS). Several challenges and insightful suggestions are put forward for future research from the viewpoint of the sand production management system (SMS). Furthermore, an innovative method for unlocking conflicts between sand production and gas extraction in muddy HBS is proposed, namely, the gravel-huff to clay-puff replacement (GCR) technique. The outlook and perspectives of this technique are presented, as well as the key challenges to be resolved.