摘要
针对低渗致密砂岩油藏压裂中压裂液对油层的污染和伤害,研究采用微生物方法修复胍胶压裂液地层伤害的机制。从油藏产出水中,以胍胶为唯一碳源采用稀释平板法分离筛选出胍胶降解菌;通过菌落和细胞形态、生理生化特征以及16S r DNA序列分析对菌株进行鉴定;通过测定菌株降解胍胶中表观黏度、平均相对分子质量变化以及对压裂液残渣和粒径的分析,评价菌株对胍胶压裂液的降解效果;并通过岩心流动模拟实验,研究压裂液对岩心的伤害及微生物修复效果。结果表明:从地层产出水中分离的7株细菌中,1株细菌可高效降解胍胶,经鉴定为Bacillus paralicheniformis(CGS)。该菌降解胍胶压裂液后,表观黏度从117 m Pa·s降低到3.3 m Pa·s,降黏率达到97.0%;平均相对分子质量从119 062降低到28 089;降解过程中有CO_2、N_2O气体的产生并代谢产生了可使胍胶降解的活性物质;压裂液残渣从81.67 mg变为51.67 mg,降低了36.73%,残渣粒径从78.598μm变为59.905μm,降低了23.78%。原始渗透率为108.70×10^(-3)和16.90×10^(-3)μm^2的岩心在压裂液污染后渗透率分别为5.18×10^(-3)和7.93×10^(-3)μm^2,经微生物修复后,渗透率恢复为92.58×10^(-3)和16.32×10^(-3)μm^2,恢复率分别为85.17%和96.57%。
Aiming at the pollution and damage of the fracturing fluid on the reservoir in low-permeability or tight reservoir,the mechanism of using microbial method to remediate the formation damage caused by guar gum fracturing fluid was studied.Guar gum degrading strains were isolated and screened by dilution-plate method using guar gum as sole carbon source.Then the bacterial strain was identified through the colony morphology,physiological-biochemical tests and 16S r DNA sequence analysis.And the effect of bacterial degradation on the guar gum fracturing fluid was investigated by the apparent viscosity,average molecular weight change,as well as the degradation of fracturing fluid residueand particle size..In addition,the effectiveness of microbial remediation was researched through the artificial sand pack.It is found that 7 bacterial strains are isolated and one strain of them is screened for the follow-up tests,which is identified as Bacillus paralicheniformis（CGS）.After using this bacterial strain to degrade the guar-based fracturing fluid,the apparent viscosity decreases from 117 m Pa·s to 3.3m Pa·s with the degradation rate of 97.00%and the average molecular weight reduces from 119 062 to 28 089.CO_2and N_2O are produced in the biodegradation and the active substrate can be synthesized by CGS to degrade the guar gum.And the insoluble residue of guar gum changes from 81.67 mg to 51.67 mg with the reduction rate of 36.73%.The particle size of the insoluble residue decreases from 78.598μm to 59.905μm with the reduction rate of 23.78%.The original permeability of sand packs are 108.70×10^（-3）and 16.90×10^（-3）μm^2,respectively,and the permeability decreases to 5.18×10^（-3）and 7.93×10^（-3）μm^2due to the fracturing fluid damage.However,the permeability can be recovered to 92.58×10^（-3）and 16.32×10^（-3）μm^2with recovery rates of 85.17%and 96.57%after the microbial remediation.
作者
马鑫
雷光伦
王志惠
达祺安
张鑫
宋萍
姚传进
MA Xin;LEI Guanglun;WANG Zhihui;DA Qi＇an;ZHANG Xin;SONG Ping;YAO Chuan jin(School of Petroleum Engineering in China University of Petroleum（East China）,Qingdao 266580,Chin)
出处
《中国石油大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2018年第4期100-110,共11页
Journal of China University of Petroleum(Edition of Natural Science)
基金
国家自然科学基金项目(51604291)
山东省自然科学基金项目(ZR2016EEB05
ZR2017MEE074)
青岛市源头创新计划应用基础研究项目(17-1-1-34-jch)
中央高校基本科研业务费专项(17CX02010A)
中国石油大学(华东)研究生创新工程项目(YCX2017023)
关键词
水力压裂
胍胶
细菌
地层伤害
hydraulic fracturing
guar gum
bacteria
formation damage
