裂缝性漏失架桥材料粒度分布研究

RESEARCH ON GRAIN SIZE DISTRIBUTION OF BRIDGING MATERIAL FOR CONTROLLING LOSS INTO FRACTURES

针对裂缝性漏失地层的堵漏,根据"应力笼"原理,对裂缝壁面承压能力进行强化,首要任务就是利用刚性材料对裂缝进行预支撑,在形成一定强度的架桥后,弹性或纤维等材料进行填充才能使得该部分承压能力增强。由于以前使用的立缝缝板、光滑缝板及缝板长度过短等问题,致使实验后无法观测到堵漏材料进入裂缝的情况,故利用自主研发的能更接近现场真实情况的不锈钢长楔形裂缝模块,开展了裂缝性漏失架桥的实验研究,对比不同材料特征粒度分布对给定宽度裂缝的架桥效果,提出一种方法来选择粒度分布进而有效的形成架桥。通过采用该裂缝模块进行研究表明,该模块有良好的模拟地层的能力,可在实验后观察内部的封堵情况;主架桥颗粒D90粒径的设计至关重要,应大于等于0.9倍的架桥处裂缝宽度且小于入口裂缝宽度;D50不仅可以增加对"喉部"处的架桥,同时可以一定程度上提高封堵压力。

To control the lost circulation into the fractures,according to the " stress cage" principle,the first task is to use rigid material to pre-support the fractures,then the elastic or fibers can be packed to reinforce the pressure loading capacity.The vertical seam plates, smooth seam plates and too short plates used before made observation of LCM entering fractures unavailable during the experiments,so a stainless steel long wedge-shaped fracture module,closer to the actual situation,was used to carry out experimental study on bridging in fractured leakage loss. By comparing the bridging effects of different particle size distribution in the cracks with a given width,a method was proposed to decide the optimum size distribution for effective bridging. The study shows that this fracture module is good at formation simulation,able to observe the internal plugging situation after the experiment. The design of D90 particle size for the main bridging material is vital,not less than the 0. 9 times of the width of the fracture section to be bridged and smaller that the width of the inlet fracture. D50 can not only increase the bridging at the throat,but also improve the sealing pressure to some extent.