中江气田沙溪庙组气藏致密砂岩储层测井评价

Logging evaluation of the tight sandstone reservoir in the gas reservoir of the Shaximiao formation within Zhongjiang gas field,China

中江气田沙溪庙组气藏砂岩储层具有岩性多样、储层致密、孔隙结构复杂、非均质性强的地质特征,这使得饱和度、渗透率等参数预测精度低,测井评价易产生偏差,因此需要改进储层参数解释模型,为此类储层的地质建模提供可靠的参数。首先分析了岩性、物性、电性、含气性以及孔隙结构特征关系;然后提出了以流动单元为基础的渗透率计算模型,并根据流动单元指数将中江气田沙溪庙组气藏砂岩储层划分为3个流动单元,在不同单元内建立不同的渗透率计算模型;最后分析Archie公式中胶结指数(m)、饱和度指数值(n)与泥质含量、孔隙结构指数的关系,并在此基础上利用可变m,n计算含水饱和度模型;最终形成了一套适合研究区致密砂岩储层测井评价的方法。所建立的测井解释模型使得渗透率和含水饱和度等参数的计算精度更高,并在生产应用中取得了良好的效果。

The sand body of the Shaximiao formation within Zhongjiang gas field exhibits a diverse lithology,dense reservoir,complex pore structure,and strong heterogeneity.These characteristics lead to low saturation and permeability accuracy predictions.The logging evaluation is also prone to error.In this study,a permeability calculation model based on flow unit is introduced by analyzing the relationships between lithology,physical property,electrical property,gas content,and pore structure.This method divides the gas reservoir of the Shaximiao formation into three flow units based on flow unit index and establishes different permeability calculation models in each unit.The correlation between the cementation(m)and saturation(n)exponent values in Archie's equation and shale content and pore structure index was analyzed.Models for calculating water saturationμsing variables m and n were established.Finally,a logging evaluation method applicable for tight sandstone reservoirs in this area was proposed.This logging interpretation model can provide more accurate permeability and water saturation measurements during production.