三维裂缝中聚合物冻胶运移形态及成胶封堵机制  

Migration and plugging mechanisms of polymer gel in 3D fractured media

作　　者：尚校森[1] 董长银[1] 皇凡生 熊春明[2] 魏发林[2] SHANG Xiaosen;DONG Changyin;HUANG Fansheng;XIONG Chunming;WEI Falin(School of Petroleum Engineering in China University of Petroleum (East China), Qingdao 266580, China;Research Institute of Petroleum Exploration and Development, PetroChina, Beijing 100083, China)

机构地区：[1]中国石油大学(华东)石油工程学院,山东青岛266580 [2]中国石油勘探开发研究院,北京100083

出　　处：《中国石油大学学报（自然科学版）》2021年第3期171-178,共8页Journal of China University of Petroleum(Edition of Natural Science)

基　　金：国家自然科学基金面上项目(52074331);山东省自然科学基金青年基金项目(ZR2020QE107);中国石油大学(华东)自主创新科研计划项目(18CX02163A)。

摘　　要：利用三维裂缝岩心模型,研究聚合物冻胶溶液在裂缝中的运移及分布形态、堵剂组分不均衡滤失形态和成胶后封堵强度,探究裂缝中冻胶堵剂的运移分布和成胶规律。结果表明聚合物冻胶溶液在三维裂缝中的运移形态可以分为裂缝流、滤失流和基质流,冻胶成胶后存在3种分布形态,即裂缝中的冻胶团、裂缝壁面的冻胶层和基质孔喉中的分散冻胶块;滤失流的存在导致冻胶溶液在裂缝中运移时存在明显的组分滤失现象,由于聚合物与交联剂分子间的相对分子质量差异,冻胶组分间存在不均衡滤失扩散,其中聚合物分子滤失量很少,交联剂离子滤失量显著;交联剂滤失后会显著降低冻胶的成胶强度,进而影响对裂缝的封堵效果;当交联剂离子归一化质量浓度低于临界浓度时,冻胶成胶后强度低,不能对三维裂缝实现有效封堵;与地面预交联方式相比,采用就地交联方式时聚合物冻胶溶液成胶后形成的冻胶层可使冻胶与裂缝壁面形成较好胶结,可显著提高对裂缝的封堵效果。Three-dimensional fractured core models were used to investigate the migration,distribution form,and disproportionate loss form of plugging agent,as well as the plugging strength after gelling,through which the migration,distribution and gelation law of gel plugging agent in fractures were studied.It is found show that the migration patterns of polymer gel solution in three-dimensional fractures can be divided into fracture flow,loss flow and matrix flow.Three gel distribution states exist after polymer gel formation,which are gel ball in fracture,gel layer on fracture surface,and dispersed gel block in adjacent matrix.The loss flow leads to the significant component filtration phenomenon when the gel solution migrates in the fracture.Due to the molecular weight difference between polymer and crosslinker,there is an unbalanced filtration diffusion among gel components,in which the polymer molecular filtration is small and the crosslinker ion filtration is significant.The latter reduces the polymer gel strength greatly,and further affects the pugging performance of polymer gel for fracture.When the normalized concentration of crosslinker ion is lower than the critical concentration,the gel strength is low after gelling,and the formed polymer gel shows unsatisfied plugging performance for fractures.Compared with the pre-crosslinking way,when the in-situ crosslinking way is applied to the polymer gelant,it shows excellent plugging performance for fracture.

关 键 词：聚合物冻胶 三维裂缝 运移形态 不均衡滤失 封堵机制 

分 类 号：TQ323.1[化学工程—合成树脂塑料工业] TE39[石油与天然气工程—油气田开发工程]