鄂尔多斯盆地靖边气田下古生界非均质性气藏的产量递减规律

鄂尔多斯盆地靖边气田下古生界气藏具有非均质性强的特点，随着开发程度的提高，气藏地层压力逐渐降低，不同区块的生产动态特征表现出明显的差异性。为了给气田的滚动开发和产能弥补提供参考依据，在气田的不同开发阶段选择了有代表性的2个高渗透区块和1个低渗透区块开展了气井定压生产试验。通过Arps产量递减分析方法，对于井口压力为13 MPa、6 MPa和3 MPa的生产条件下的试验数据进行了分析，揭示了该气田下古生界非均质性气藏的产量递减规律：高渗透区块在高压和低压条件下的产量递减均符合指数递减类型，且随着井口压力的降低，产量递减率趋缓；低渗透区块的产量递减符合双曲递减类型；同时高、低渗透区块的产量递减率又表现出一定的共性，在采气速度一定的条件下，产量递减率与井口压力呈正比，与动用地质储量、泄流半径和储层能量补给速度呈反比。

Deliverability decline law of heterogeneous Lower Paleozoic gas reservoirs in the Jingbian Gas Field, Ordos Basin

The Paleozoic gas reservoirs in the Jingbian Gas Field, Ordos Basin, are characterized by strong heterogeneity. With the rapid development of this gas field, the gas reservoir formation pressure is gradually reduced and the production dynamic characteristics of different blocks are significantly distinct from each other. To provide a reference for the progressive development and production capacity compensation, typical blocks include two high permeability blocks and one low permeability block are selected to undergo a pilot test of gas well constant pressure production at different development stages of this field. The test data, collected from different wells with wellhead pressure of 13, 6 and 3 MPa respectively, is analyzed through the Arps equation, and the results reveal the production decline law of the lower Paleozoic gas reservoirs in the Jingbian Gas Field. (1) The production of high permeability blocks under high and low pressure is in exponential decline, while the production decline rate tends to be flat lined with the decreasing wellhead pressure. (2) The production of low permeability blocks is in hyperbolic decline. (3) The production decline law of high and low permeability blocks have some common features, that is, under a certain gas production rate, the production decline rate is proportional to wellhead pressure, but is inversely proportional to dynamic producing reserve, drainage radius, and reservoir energy recharge speed.