多层段致密砂岩气藏有利区评价方法再认识

Recognition of evaluation method for favorable area of multi-layer tight sandstone gas reservoir

鄂尔多斯盆地神木、米脂、苏里格等多个气田都具有多层段含气的特征,且都属于典型的致密砂岩气藏。针对该类气藏开发难点,本次以神木气田为例,基于前人研究成果,引入PI因子的概念,进一步优化完善多层段致密砂岩气藏有利区评价方法。首先,优选与单层产能有关的地质参数进行归一化并分析其影响权重,建立单层有利区评价标准;其次,依据单层PI因子,结合产气剖面测试,明确不同层段的产能贡献权重,进而加权求取叠合层综合指数;最后,根据经济极限评价,明确综合指数经济开发界限。该方法使得有利区优选由传统的"多层定性描述"转变为现在实用的"归一层定量表征",在神木气田的高效、规模开发中得到了广泛应用。

Many gasfields in Ordos basin, such as Shenmu, Mizhi and Sulige, all have the characteristics of multi-layer gas bearing, and all belong to typical tight sandstone gas reservoirs. In view of the difficulties in the development of this kind of gas reservoir, taking Shenmu gasfield as an example, based on the previous research results, the concept of PI factor is introduced to further optimize and perfect the evaluation method of favorable area of multi-layer tight sandstone gas reservoir.Firstly, the geological parameters related to singlelayer productivity are optimized for normalization and their influence weights are analyzed,and the evaluation criteria for single-layer favorable areas are established. Secondly, according to the single-layer PI factor, combined with the gas production profile test, the productivity contribution weight of different layers is defined,and then the composite index of stacking layer is calculated by weighting. Finally, the economic development limits of the composite index are defined according to the economic limit evaluation. This method transforms the optimal selection of favorable area from traditional "multi-layer qualitative description" to "normalized layer quantitative characterization", which has been widely used in the high efficiency and scale development of Shenmu gasfield.