Abstract:

Prerequisites for hydrate production field test are whether the target meets the geological and engineering conditions for recoverability. However, since previous work is limited, there is no method to quantitatively evaluate the targets. To overcome the optimization problem of hydrate production test target wells, the comprehensive evaluation objective system is established from both geological and engineering perspectives. The six geological factors include porosity, hydrate thickness, hydrate saturation, intrinsic permeability, in-situ temperature and pressure; whilst the four engineering factors are water depth, underwater gradient, intensity and overlying layer thickness. The evaluation method (based on fuzzy comprehensive evaluation) is put forward to preliminary determine the comprehensive quantitative evaluation of production test target. Based on four typical hydrate coring sites (XX01, XX02, XX03 and XX04) in the Shenhu area of the northern South China Sea, the weights of the geological and engineering factors were estimated. The results show that the gas production potential at these four sites is unattractive. Nonetheless, site XX02 has the highest weight and was chosen as the target. The method of this study yielded good outcomes, and can provide support to optimize hydrate mining targets in intelligent quantification and promote hydrate industrialization in the future.

Key words: marine natural gas hydrate, production target well, quantitative evaluation, Shenhu area