{"title":"Synthesis and evaluation of salt tolerant delayed-crosslinking fracturing fluid system in ultra-deep high temperature wells","authors":"Cheng Jian, Yi Yu, Dingze Yu, Ping Chen, Jing Yan, Xuefeng Chen","doi":"10.1007/s00396-024-05296-1","DOIUrl":null,"url":null,"abstract":"<div><p>The Tarim area, characterized by deep reservoirs, high temperatures, and limited fresh water resources, necessitates a fracturing fluid system that exhibits excellent temperature shear resistance, low friction, and salinity tolerance. This study presents the development of a zwitterionic hydrophobic polymer, HPC-5, as an effective thickener using five types of polymeric monomers, including AM, AA, DMC, AMPS, and a non-ionic hydrophobic monomer. The method employed for synthesis was free-radical polymerization in solution. A series of experiments including viscosity measurement with variation of salinity, solubility and drag reduction test, crosslinking test, thermal and shear resistance, sand-carrying test, gel breaking evaluation, and core damage test were conduct under the simulated reservoir conditions. The zwitterionic design imparts great salt tolerance to HPC-5, and the apparent viscosities of HPC-5 solutions can maintain comparably high values with 10×10<sup>4</sup> ppm NaCl and CaCl<sub>2</sub> concentration. Meanwhile, the molecules of HPC-5 associate with each other to form tight net structures, resulting in an excellent viscoelasticity of the solution. To achieve high pump rate during hydraulic fracturing operation in ultra-deep reservoirs, the delayed crosslinking agent ZDC-L was prepared for forming a delayed crosslinking gel fracturing fluid system using reservoir brine, and the drag reduction rate can reach over 70% before crossing link within 4 min. Under pH = 4 conditions, the crosslinking time can be significantly delayed to over 4 min while maintaining exceptional temperature resistance up to 160 ℃ for the gel. These properties make it highly suitable for hydraulic fracturing operations in ultra-deep wells with temperatures reaching up to 7000 m depth at pump rates of 4~5m<sup>3</sup>/min.</p><h3>Graphical abstract</h3>\n<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":520,"journal":{"name":"Colloid and Polymer Science","volume":"302 10","pages":"1591 - 1601"},"PeriodicalIF":2.2000,"publicationDate":"2024-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Colloid and Polymer Science","FirstCategoryId":"92","ListUrlMain":"https://link.springer.com/article/10.1007/s00396-024-05296-1","RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"CHEMISTRY, PHYSICAL","Score":null,"Total":0}
引用次数: 0
Abstract
The Tarim area, characterized by deep reservoirs, high temperatures, and limited fresh water resources, necessitates a fracturing fluid system that exhibits excellent temperature shear resistance, low friction, and salinity tolerance. This study presents the development of a zwitterionic hydrophobic polymer, HPC-5, as an effective thickener using five types of polymeric monomers, including AM, AA, DMC, AMPS, and a non-ionic hydrophobic monomer. The method employed for synthesis was free-radical polymerization in solution. A series of experiments including viscosity measurement with variation of salinity, solubility and drag reduction test, crosslinking test, thermal and shear resistance, sand-carrying test, gel breaking evaluation, and core damage test were conduct under the simulated reservoir conditions. The zwitterionic design imparts great salt tolerance to HPC-5, and the apparent viscosities of HPC-5 solutions can maintain comparably high values with 10×104 ppm NaCl and CaCl2 concentration. Meanwhile, the molecules of HPC-5 associate with each other to form tight net structures, resulting in an excellent viscoelasticity of the solution. To achieve high pump rate during hydraulic fracturing operation in ultra-deep reservoirs, the delayed crosslinking agent ZDC-L was prepared for forming a delayed crosslinking gel fracturing fluid system using reservoir brine, and the drag reduction rate can reach over 70% before crossing link within 4 min. Under pH = 4 conditions, the crosslinking time can be significantly delayed to over 4 min while maintaining exceptional temperature resistance up to 160 ℃ for the gel. These properties make it highly suitable for hydraulic fracturing operations in ultra-deep wells with temperatures reaching up to 7000 m depth at pump rates of 4~5m3/min.
期刊介绍:
Colloid and Polymer Science - a leading international journal of longstanding tradition - is devoted to colloid and polymer science and its interdisciplinary interactions. As such, it responds to a demand which has lost none of its actuality as revealed in the trends of contemporary materials science.