基于地震多属性的郑庄区块煤层气开发甜点区优选

Analysis of Key Geological Parameters of Zhengzhuang Coalbed Methane Reservoir and Forecast of Sweet Spots: Investigated by Multiple Seismic Attributes

地震属性受多种地质因素的影响,单一地震属性很难准确地反映煤层气储层综合地质特征。寻找能够降低地震属性多解性的方法,准确预测主地质参数,是评价煤层气有利区的关键。根据煤层厚度、含气量和渗透率分别与振幅类、频率类和曲率类地震属性具有较高相关性的特点,通过地震多属性组合变换的方法,建立了基于地震属性分析的煤层气主地质参数预测模型。然后,建立动态权重系数中值法,以中值评价值出现的最高频率,确定主地质参数在煤层气有利区优选中所占的权重,并基于评价值函数实现有利开发区块优选。利用该方法对沁水盆地郑庄地区的预测结果表明:最有利开发甜点区位于北部的59-60-57-55井区,次级有利开发甜点区位于东北部的53-62-49-45井区。

Seismic attribute is related to several geological factors,and thus any one attribute is hard to represent the complex and comprehensive geological characteristics of coalbed methane（ CBM） reservoir. The key for selecting the sweet spot of CBM exploration by using seismic attributes is to find an accurate explanation of the seismic attribute characteristics,and to decide the main geological parameters of CBM reservoir. In the study area,the coal thickness,gas content,and permeability have high correlations with seismic attributes of amplitudes,frequencies and curvatures,respectively. Based on these correlations and a transformation of multi-seismic attributes,this paper provides a forecast model for the main geological parameters of CBM reservoir. Then,a dynamic weight coefficient median method is used to determine the weightings of the key geological parameters that are related to the highest frequency of median evaluation value. Finally,the sweet spots of CBM production are forecasted by using the equations of evaluation values. The evaluation results of Zhengzhuang field show that the most favorable spot is located in the 59- 60- 57- 55 well block in the northern part,and the secondary favorable spot is around the 53- 62- 49- 45 well block in the northeastern part.