【摘要】 在裸眼水平井分段压裂过程中,裸眼封隔器下入裸眼水平井段时会与岩屑床接触,一方面下入的摩擦阻力逐渐增大,另一方面堆积在封隔器前方的岩屑容易引起砂卡且封隔器胶筒被岩屑磨损,有可能造成坐封性能下降甚至封隔失效。为此,设计并制作模拟实验装置,研究岩屑床对封隔器下入裸眼水平井段过程的影响,再根据实验现象对原有封隔器结构进行设计改进,设计了应用于裸眼封隔器的疏砂槽结构。实验结果表明:①在裸眼封隔器下入过程中,封隔器会被砂堆支撑起来,使其与上井壁接触,造成摩阻力的急剧增大进而发生砂卡,且封隔器所受摩擦阻力随下入位移和岩屑含量的增加而增大;②添加疏砂槽结构后,岩屑从疏砂槽流过,减少封隔器前端的岩屑堆积,减小封隔器通过井眼的摩擦阻力,从而减轻胶筒磨损;③改进封隔器模型的疏砂槽个数对疏砂减阻效果影响显著,该实验条件下疏砂槽个数为5时,疏砂效果为最好。结论认为,该研究成果为裸眼封隔器相关结构进一步优化提供了研究思路和室内实验依据。更多还原

【Abstract】 In the process of staged fracturing in an open-hole horizontal well, an open-hole packer contacts the cuttings bed when it goes down to the open-hole horizontal section. As a result, the running friction resistance is increased gradually. And on the other hand, the cuttings accumulated in front of the packer tend to result in sand sticking and wear the packer rubber, which may lead to the deterioration of setting performance and the failure of the packer. In this regard, this paper designed and manufactured a simulation experiment device to research the effect of the cuttings on the running process of the packer into the open-hole horizontal sections. Then, based on the experimental results, the original packer was structurally improved and sand dredging grooves applied to an open-hole packer was designed. And the following experimental results were obtained. First, in the process of running into the hole, the open-hole packer is supported by the cuttings pile to contact the upper wall, resulting in a sharp increase of friction resistance and then sand sticking. And the friction resistance applied on the packer increases with the increase of running displacement and cuttings content. Second, after the packer is equipped with the structure of the sand dredging groove, cuttings flow through the sand dredging groove. As a result, the cuttings accumulation in front of the packer and the friction resistance on the packer running through the hole are reduced, and consequently the wear of packer rubber is diminished. Third, the number of sand dredging grooves in the improved packer model has a significant effect on sand dredging and friction reduction. In this experiment, the sand dredging effect is the best when the number of sand dredging grooves is up to 5. In conclusion, the research results provide a research idea and laboratory experiment basis for the further structure optimization of openhole packers.更多还原