含沥青储层的测井识别及评价

Log Identification and Evaluation for Bitumen-bearing Reservoir

以塔里木盆地某区块泥盆系K组含沥青储层为例探讨含沥青储层的测井评价方法。分析沥青对储层物性及产能的影响,通过2口井测井曲线的对比分析,指出含沥青储层的测井响应特征,并建立含沥青储层的测井识别图版,将含沥青储层与泥质区分开。在定性识别的基础上,利用自然伽马与中子-密度交会法计算储层泥质含量的差值作为储层沥青相对含量,建立有效孔隙度校正模型,提高有效孔隙度计算精度,为准确评价储层提供依据。通过分析储层沥青相对含量及孔隙度在平面上的变化趋势,指出区块内油藏东部受破坏程度比西部强。

The deposition ot bitumen m reservoir has seriousbad effect on physicalproperties productivity of reservoir, which may leads to wrong log interpretation results. This paper takes the bitumen-bearing reservoir in Devonian K group in a zone in Talimu basin as an example to discuss how to evaluate bitumen-bearing reservoir. First of all, the effect of bitumen on the physical properties and productivity of reservoir is analyzed and then the log responses of bitumen-bearing reservoir are identified by comparing logs from two different wells. A cross-plot for identifying bitumen-bearing reservoir is created to distinguish between bitumen and shale. The relative abundance of bitumen in reservoir is derived from the difference between shale content which is calculated with gamma log and from neutron-density cross-plot. A formula for porosity correction is created, which helps to improve the accuracy of porosity and provide foundation for accurate reservoir evaluation. At last, the horizontal variation trend of relative abundance of bitumen in reservoir is studied, which shows that the oil pool is damaged more seriously in the east part of the area than in the west.