Effect of heterogeneous hydrate distribution on hydrate production under different hole combinations

Few laboratory studies were focused on the effect of heterogeneous hydrate distribution on hydrate production. Herein, in a horizontal pressure vessel with hole density of 8.3 holes/m and hole diameter of 2.5 cm, this effect was defined by depressurization in seven samples with a hydrate saturation of 23.2% under various hole combinations. Hydrate distribution and its heterogeneity degree were represented by the net increase of the electrical resistance during hydrate formation and the corresponding variation coefficient and then compared with depressurization effects. The results showed that hydrate distribution possessed a heterogeneity degree range of 0.96–1.97. Under a large heterogeneity degree, water production was aggravated. Thus, temperature loss and the sensible heat use ratio under one-hole combination was separately increased by 0.21 °C and 0.12, while gas production and hydrate dissociation ratio was reduced by 4.332 L and 3.79%, respectively. An apparent effect of hydrate distribution on water production was observed within 1–2 holes. This effect increased temperature loss by 0.11 °C and the sensible heat use ratio by 0.084, and reduced gas production by 6.564 L. Exceeding 1–2 holes, hole amounts governed severe water production. This work may advantage to understand the influencing mechanism of hydrate distribution on hydrate production.