Inversion method of key reservoir parameters for horizontal well production of marine gas hydrate

Key words:  natural gas hydrates  parameters inversion  tilt field  neighborhood algorithm

Abstract:

A tilt-meter monitoring method can be used to evaluate the dynamic gas output in horizontal wells during marine gas hydrate exploitation, while the objective function may fall into a large convergence area because of the complementarity between the volume parameters of different well sections. Thus, the accuracy of the inversion method will directly affect its results. In this work, a key reservoir parameter inversion method based on neighborhood algorithm was proposed, and a case study was carried out based on the geological conditions of Shenhu area in the South China Sea. The volume parameters of different sections of horizontal wells were inverted and calculated using the synthesized seabed tilt field data, and the influence of different noise levels and model spacing on the inversion results was studied. The results show that, compared with the direct grid search method, the proposed method has higher computational efficiency and better real-time performance on the premise of ensuring the convergence effect. Compared with the simulated annealing method, the proposed method also has higher inversion accuracy. When the output of water and sand form different well sections are small or the proportion of them to the changing volume of the reservoir is the same, this method can provide a better algorithm basis for the dynamic evaluation of marine gas hydrate production via horizontal wells.