Геофизика geol.

[solig]

Пожалста, помогите разобраться, в чем разница между net pay и net sand.
Перевод вроде один и тот же, но понятия разные. Контекста нет, но почему-то net sand употребляется, связанным с пористостью и объемом глинистости, а net pay - с водонасыщенностью?
Заранее благодарен

[dfc]

здесь про net pay
In general, petrophysicists and geologists tend to view net pay from a "static" perspective, whereas reservoir engineers view net pay from a "dynamic" perspective. In other words, the petrophysical/geological view is that net pay represents that portion of the rock that "contains" hydrocarbons, whereas the reservoir engineer views net pay as being that portion of the rock that "contains and produces" hydrocarbons. In fact, some engineers (reserve engineers) indicate that production should be in "paying quantities." Clearly, these different perceptions of net pay can create confusion between various professionals within the same organization and between organizations, host governments, and other entities...

http://www.spe.org/spe/jsp/basic/0,,1104_1575_1040472,00.html

[10-4]

net sand = песчанистость, суммарная мощность проницаемых прослоев
NTG = net to gross = песчанистость, коэффициент песчанистости
net pay = эффективная толщина (коллектора)

[solig]

Благодарю!