加拿大油砂储层测井评价关键技术

Key Technologies for Log Evaluation of Oil Sand Reservoirs in Canada

世界上85%的油砂集中在加拿大阿尔伯塔省,其储层具有高密度、高孔隙度渗透率、高黏度、分布广、厚度大的特点。目前,油砂的研究多注重于开采方面,对测井资料的应用评价较少涉及。从生产角度出发,针对油砂储层骨架特殊、物性参数求取难、SAGD部署开发井需要避开低渗透夹层等问题,选取加拿大某区特征油砂井,对油砂测井解释评价中的关键技术进行了研究。通过非线性优化骨架参数,使用粒度中值建立地区渗透率模型,岩心刻度确定含水饱和度计算参数等手段,提高了常规测井解释精度。利用成像测井分辨率高的特点,充分挖掘成像测井资料的地质信息,首次系统建立岩相识别图版库。通过常规和成像相结合建立岩相同SAGD分区的对应关系,对SAGD过程中可能阻碍油气自由流动的区域(主要是薄的泥页岩)进行划分,为后期开发方案的制定提供了测井依据。目前该评价方法已在加拿大实际应用上百口井,其评价结果有效地支持了矿区储量复算,对后期的SAGD布井也起到了指导作用。

The eighty-five pereent of the world’s oil sand is located in Alberta, Canada. Oil sand reservoirs are characterized by high density, porosity, permeability and viscosity, and wide and thick distribution. At present, researches on oil sand are mainly focused on production, but less on the evaluation and application of log data. Based on characteristic oil sand wells in Canada, investigates the key technologies for log interpretation and evaluation from the point of production, and aiming at the special matrix of oil sand reservoir, difficulties in obtaining accurate physical parameters, and how to avoid less permeable interlayers in SAGD development wells, etc. The accuracy of conventional log interpretation can be improved by means of non-linear optimization of reservoir matrix parameters, establishment of regional permeability model with median grain size and determination of water saturation calculation parameters by core calibration. By fully taking use of the geological information contained in imaging log data which have high resolution, a systematic lithofacies recognition chart library has been established for the first time. The corresponding relationship between the same SAGD zones was established by combining conventional and imaging log data, and the zones(mainly thin shale) that may hinder free oil and gas flow in the SAGD process were divided, providing a logging basis for later development plans. By now the evaluation method has been applied to hundreds of wells in Canada. The results effectively support re-estimation of reserve, and play a guiding role in future locations of SAGD wells.