??????????μ????????

根据天然气的受力情况及气水界面的变化状态，将深盆气藏划分为3个演化阶段；生长阶段、稳定阶段、萎缩阶段。在其生长阶段，内部压力结构在垂向上表现为下述三种情况之一：（1）高压异常；（2）高压异常→正常压力；（3）高压异常→正常压力→低压异常。在其稳定阶段和萎缩阶段，内部压力结构表现为低压异常，尤其在萎缩阶段其低压特征表现得更为明显。由于气体运移和储层非均质性的影响，气藏内部压力随深度呈非线性变化，下部的压力梯度大于上部压力梯度，压力梯度线偏离均质气藏静态压力梯度线。

Accumulating Stages and Pressure Structure of Deep Basin Gas

??The deep basin gas is accumulated in the particular unconventional traps, which is characterized by tight reservoir, reversal distribution between gas and water, abnormal pressure, and great potential of resources. The evolution of deep basin gas can be marked off three stages according to the gas endured forces and the movement of the gas water contact. At its developing stage, the vertical profile of pressure structure represents one of the three forms: ??supernormal pressure; ??supernormal??normal hydrostatic pressure; ??supernormal pressure??normal hydrostatic pressure??subnormal pressure. At its steady stage and especially the shrinking stage, it represents the form of subnormal pressure. Due to the migration of gas and the heterogeneity of reservoirs, the pressure changes non linearly along with the depth. The pressure gradient at the lower part is higher than that at the upper part; and the pressure gradient is greater than than that of the static gas pressure.