挖掘系数法在苏里格气田马五碳酸盐岩储层流体识别中的应用

马五_4~1碳酸盐岩储层是苏里格气田勘探开发的目的层位之一,储层类型多样、孔隙结构复杂造成岩电参数变化大,且地层水矿化度分布范围广,基于电阻率的流体判识方法难以有效识别高电阻率水层与低电阻气率层。利用挖掘系数法基于中子孔隙度测井岩石体积模型得到挖掘系数与含气饱和度的关系。天然气和地层水的含氢指数差别较大,挖掘系数与含气饱和度正相关;相较电法测井,挖掘系数受到的影响因素较少;对含气饱和度较低的储层,挖掘系数受喉道半径控制,判识误差大。实际资料的处理解释结果证明,该方法能够准确判识碳酸盐岩储层的流体性质。

Application of Excavation Coefficient to Fluid Identification for Ma541 Carbonate Gas Reservoirs in Sulige Gas Field

Ma541 Carbonate gas reservoir is the main target of exploration and production in Sulige gas field which is the diverse reservoir types and complicated pore structure with wide range of salinity distribution, so, it is difficult to identify the high resistivity water layer and low resistivity gas layer by fluid identification method based on resistivity.Based on rock volume model of neutron porosity logging, the relationship between excavation coefficient and gas saturation can be obtained from the excavation coefficient method.The hydrogen index different of natural gas and formation water is large, the excavation coefficient is positively correlated with gas saturation;Compared with electrical logging, the excavation coefficient is less affected;In the reservoir with low gas saturation, the excavation coefficient is controlled by throat radius, and the error is large.The practice log interpretation results show that the method can accurately identify the fluid properties of carbonate reservoir.