特低渗透油藏注水粘土稳定剂及评价方法——以海拉尔盆地贝尔油田为例

Study on clay stabilizer and evaluation method for extra-low permeability oil field-a ease study of Beier oillield

粘土膨胀与运移是特低渗透水敏地层注水开发过程中的突出问题。以平均渗透率为1.83×10-3μm2的贝尔油田为例,采用天然岩心对地层的水敏性及粘土稳定剂进行了研究,并且对目前广泛采用的粘土稳定剂静态与动态评价方法在特低渗透油田的适用性进行了探讨。分析了水敏导致的渗透率损失对中、高渗透油藏与低渗透油藏产生的不同结果及其原因。通过对3种不同类型粘土稳定剂评价结果,发现室内合成的粘土稳定剂SN的防膨性能优于氯化钾、聚二甲基二烯丙基氯化铵及环氧氯丙烷与二甲胺共聚物3种粘土稳定剂。实验结果表明:贝尔油田存在中等程度水敏性,粘土稳定剂SN对其具有较好的防膨效果。水敏对于特低渗透油藏渗透率的影响要远大于中、高渗透油藏。特低渗透油藏粘土的少量膨胀,会导致渗透率的大幅度降低。单纯的静态粘土稳定剂评价方法不适合特低渗透油藏注水过程中所用粘土稳定剂评价,应结合动态评价的实际渗透率损失结果进行粘土稳定剂优选。

Clay swelling and migration are serious problems for extra-low permeability oil field. In this paper, the water sensitivity and clay stabilizer are studied with drilling core of Beier oil field, and the average permeability is 1.83×10-3 μm2. Adaptability of normal clay stabilizer evaluation methods for extra-low permeability oil field is also discussed herein. These methods include static method and dynamic method. Moreover, it is demonstrated by the study that the performance difference in high permeability and low permeability reservoirs are mainly resulted from clay swelling. Three different types of clay stabilizers are evaluated. The result shows that clay stabilizer SN synthesized in lab is much more effective than others. And, the water sensitivity of the reservoir is high. Experimental results show that water sensitivity influences more the extra-low permeability oil field than high permeability oil field. Little clay expansion will decrease permeability greatly in extra-low permeability oil field. Single static evaluation method is not suitable to optimize clay stabilizer for extra-low permeability oil field.