Study on Critical Parameters of Nitrogen Injection during In Situ Modification in Oil Shale

Shilin Tao, Xueqi Cen, Xiaocong Yu (), Junqing Hu and Changbin Kan ()
Additional contact information
Shilin Tao: School of Petroleum Engineering, China University of Geosciences, Wuhan 430074, China
Xueqi Cen: State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development, SINOPEC, Beijing 102206, China
Xiaocong Yu: School of Petroleum Engineering, China University of Geosciences, Wuhan 430074, China
Junqing Hu: The First Oil Production Plant of Daqing Oilfield Corporation Limited, CNPC, Daqing 163000, China
Changbin Kan: School of Petroleum Engineering, China University of Geosciences, Wuhan 430074, China

Energies, 2022, vol. 15, issue 21, 1-14

Abstract: During in situ modification, inappropriate thermal insulation measures applied in annulus of injection wells will cause injection technical problems such as tremendous heat loss, wellhead lifting, serious casing damages, and corrosion. Continuous nitrogen injection into annulus is an effective measure to realize thermal insulation of injection wells. The critical displacement parameters of nitrogen injection in annulus are a key factor in the process of continuous nitrogen injection. However, the critical nitrogen injection rate under various working conditions, such as different well types, different wellhead steam parameters, and insulation pipe parameters, was not fully considered and studied. In this paper, the annular critical nitrogen injection displacement model was established based on the completion structure of injection well by applying the basic principles of heat transfer and fluid mechanics comprehensively. The influencing factors of critical nitrogen injection displacement were calculated and analyzed. The results show that the annular thermal resistance of horizontal wells is larger than that of directional wells for different well types, and the critical nitrogen injection displacement required is higher. The parameter sensitivity analysis shows that with the increase of pressure, steam displacement, and steam dryness, the required critical nitrogen injection displacement rate increases nearly quadratically. However, with the increase of the length and thermal conductivity of insulation pipe, the critical nitrogen injection displacement decreases cubically. The critical nitrogen injection can be reduced by reducing the annular area of the casing annulus and lowering the string deeply. The research results can provide key basic theoretical guidance for improving the heat utilization efficiency of in situ modified wells and reducing the casing damage rate for hot injection wells.

Keywords: in situ modification of oil shale; thermal injection well; nitrogen insulation; critical nitrogen displacement; thermal insulation process (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2022
References: View complete reference list from CitEc
Citations:

Downloads: (external link)
https://www.mdpi.com/1996-1073/15/21/8034/pdf (application/pdf)
https://www.mdpi.com/1996-1073/15/21/8034/ (text/html)

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:gam:jeners:v:15:y:2022:i:21:p:8034-:d:956661

Access Statistics for this article

Energies is currently edited by Ms. Agatha Cao

More articles in Energies from MDPI
Bibliographic data for series maintained by MDPI Indexing Manager ().