Steeply tilted foreset beds are formed only under very restricted condition.
陡斜的前积层只有在非常严格的条件下才能形成。
Some of the facies like mounds, drapings, foreset and chaotic facies are believed to be directly related to oil and gas accumulations.
一些地震相，如丘状相、披复相、前积相和杂乱相与油气聚集有直接的关系。
Triassic Yanchang deltaic oil-gas located in east of basin with two kinds of oil-gas reservoir sequence, the lacustrine facies delta foreset sand body and plain distributary sand body.
