鄂尔多斯盆地志丹地区长9致密储层流体识别

Fluild identification of tight reservoir in Chang 9 Formation,Ordos Basin

鄂尔多斯盆地志丹地区长9致密砂岩储层地质特征复杂,低阻油层与常规油层、高阻水层与常规水层共存,导致油水层测井响应特征差异性微弱,流体识别精度极低。该研究根据储层地质特征及其测井响应特征,优选能够有效放大或突出流体性质差异性的测井参数,利用视自然电位-实测自然电位和声波时差-深感应电阻率重叠图法、声波时差、电阻率、自然电位异常幅度、自然伽马和组合参数(RILD×Δt×Cw)交会图法及Archie公式法综合识别和校验流体性质。研究表明,重叠图法能初步识别常规油、油水层和水层或干层,交会图法能进一步识别低阻油层和高阻水层,Archie公式法能通过计算含油饱和度定量识别流体性质。这种定性和定量综合识别方法能够有效识别出常规油层、低阻油层,常规水层、高阻水层和高伽马砂岩的水层,研究思路和方法有效可行,预测结果可以为鄂尔多斯盆地延长组致密储层的油气勘探提供可靠的依据。

The tight sand reservoir of Chang 9 Formation in Zhidan area,Ordos Basin,has complex geological characteristics of low resistivity and conventional oil layer,high resistivity and conventional water layer coexist,resulting in oil and water layer in the logging response characteristic difference of oil-water layer weak contrast,fluid identification accuracy is extremely low. Through the analysis of the geological characteristics and logging response characteristics of tight reservoir,logging parameters optimization can be effectively enlarged or prominent the difference of fluid properties. Using calculated natural potential-measured natural potential and acoustictime-deep induction resistivity overlap graph method,acoustictime,resistivity,the natural potential anomaly magnitude,natural gamma and combination parameters（ RILD× Δt × Cw） by crossplot analysis,and Archie formula method can comprehensively identify and verify the fluid properties. The research shows that the overlap can be a preliminary identification of conventional oil,oil-water layer and water or dry layer,thenaccording to the crossplot graph methods,the low resistivity oil layer and high resistivity water layer can be further identificatied,and Archie formula method can quantitatively identify the fluid properties by calculating oil saturation. The comprehensive identification methods can effectively identify the conventional and low resistivity oil layer,conventional and high resistivity water layer,and high gamma sandstone layer,this kind of research idea and method is effective and feasible,and the prediction results can provide reliable basis for oil and gas exploration of tight reservoir in Yanchang Formation,Ordos Basin.