疏松砂岩地层压裂充填支撑剂粒径优选

Selection of proppant size in frac and pack treatment on unconsolid sandstone reservoir

在疏松软地层中实施压裂充填工艺,出砂和支撑剂的嵌入是造成裂缝失效的主要因素,而两者都与支撑剂的粒径有密切的关系。针对金县油田高渗储层,设计模拟裂缝壁面的嵌入与砂侵和裂缝端部的砂侵试验。在不同压力下,对两种不同粒度组成的模拟地层砂进行测试,获得支撑剂在软地层中的嵌入程度、不同粒径支撑剂及其组合下的出砂量、出砂粒径以及砂侵后的导流能力。结果表明:在软地层中,支撑剂的嵌入程度随支撑剂粒径的增加而增大,随地层砂粒度中值的增大而减小;压裂充填防砂支撑剂粒径应优选为5～9倍的地层砂粒度中值;支撑剂粒径是地层砂粒度中值的6～9倍时,可形成内部砂桥;适合于压裂充填防砂的支撑剂粒径组合方案是粒径为地层砂粒度中值6～9倍的支撑剂与小于6倍的支撑剂体积比为3∶1。

For frac and pack in the unconsolid soft formation,sand production and proppant embedment which have a close relationship with proppant size are the important factors leading to fracturing failure.The experiments were carried out by two new measurement methods for simulating proppant embedment and sand invasion about fracture wall and front end on high permeability reservoirs of Jinxian Oilfield.Under different pressure,the experiments on testing two kinds of simulated formation sand with different grain size were carried out,and the proppant embedment degree in the soft formation,the amount and particle size of sand production,the fracture conductivity after sand invasion were obtained.The results show that the embedment degree increases with the increase of proppant size and decreases with the increase of sand size in the soft formation.The proppant size for frac and pack is about 5-9 times the size of sand.When the proppant size is 6-9 times median size of sand,interior sand bridge can form.When the ratio of proppant for 6-9 times the size of sand and proppant less than 6 times the size of sand is 3∶1,the combination is appropriate.