致密砂岩气层测井识别与评价技术——以苏里格气田为例

Logging Identification and Evaluation Technique of Tight Sandstone Gas Reservoirs: Taking Sulige Gas Field as an Example

苏里格气田上古生界致密砂岩储层渗透率低、孔隙类型多样、非均质性强,导致岩石物理响应特征复杂,气水层识别与含气饱和度准确定量评价难度大。结合研究区致密砂岩储层的特点以及气层的测井响应特征,优选了4种适用的气层识别方法,通过多种方法的综合指示能有效识别气层;根据储层孔隙结构与岩电响应关系特征,确立了双孔隙饱和度模型在研究区的适用性并建立了适用于研究区的饱和度模型岩电参数。通过研究区大量井中的应用表明,上述气层识别方法在致密砂岩气层判识中具有良好的应用效果,与阿尔奇模型相比,利用双孔模型及其岩电参数计算的含气饱和度具有更高的精度,更符合气藏的实际规律和岩石物理特征。上述方法为致密砂岩气层测井识别与评价提供了有效途径。

Tight sandstone reservoirs of Upper Palaeozoic have characteristics with low permeability, various pore types and strong heterogeneity in Sulige gas field which lead to complex rock physical response char- acteristics. All the above causes the difficulty in identifying gas and water layers and quantitatively evalua- ting accurate gas saturation. Combining with the characteristics of tight sandstone reservoir in the study ar ea and the logging response characteristics of gas layers, four kinds of applicable methods to identify gas layers were optimized and through comprehensive utilization of the above methods, gas layers were identi lied effectively. According to the characteristics of reservoir pore structure and rock electric response, the applicability of dual porosity saturation model in the research area was determined and rock-electricity pa- rameters of the saturation model which was applicable to the research areas were also established. Through applying these methods to a large number of wells,it shows that the four methods have good application effect in identifying gas layers in tight sandstone gas reservoirs. Compared with the Archie model, the gas saturation calculated by dual porosity saturation model and corresponding rock electricity parameters have higher accuracy,which have higher accordance to the actual law of gas reservoir and physical characteristics of rocks. The above methods provide effective way for logging identification and evaluation of tight sand- stone gas reservoirs.