首页|Combined use of fly ash and silica to prevent the long-term strength retrogression of oil well cement set and cured at HPHT conditions

Combined use of fly ash and silica to prevent the long-term strength retrogression of oil well cement set and cured at HPHT conditions

扫码查看
原文链接
  • NETL
  • NSTL
  • 万方数据
The long-term strength retrogression of silica-enriched oil well cement poses a significant threat to wellbore integrity in deep and ultra-deep wells,which is a major obstacle for deep petroleum and geothermal energy development.Previous attempts to address this problem has been unsatisfactory because they can only reduce the strength decline rate.This study presents a new solution to this problem by incorporating fly ash to the traditional silica-cement systems.The influences of fly ash and silica on the strength retrogression behavior of oil well cement systems directly set and cured under the condition of 200 ℃ and 50 MPa are investigated.Test results indicate that the slurries containing only silica or fly ash experience severe strength retrogression from 2 to 30 d curing,while the slurries con-taining both fly ash and silica experience strength enhancement from 2 to 90 d.The strength test results are corroborated by further evidences from permeability tests as well as microstructure analysis of set cement.Composition of set cement evaluated by quantitative X-ray diffraction analyses with partial or no known crystal structure(PONKCS)method and thermogravimetry analyses revealed that the conversion of amorphous C-(A)-S-H to crystalline phases is the primary cause of long-term strength retrogression.The addition of fly ash can reduce the initial amount of C-(A)-S-H in the set cement,and its combined use with silica can prevent the crystallization of C-(A)-S-H,which is believed to be the working mechanism of this new admixture in improving long-term strength stability of oil well cement systems.

Fly ashLong-term strength retrogressionHigh temperatureQuantitative X-ray diffraction(QXRD)Partial or no known crystal structure(PONKCS)

Guo-Dong Cheng、Xue-Yu Pang、Jin-Sheng Sun、Zheng-Song Qiu、Chuang-Chuang Wang、Jian-Kun Qin、Ning Li

展开 >

School of Petroleum Engineering,China University of Petroleum(East China),Qingdao 266580,Shandong,China

School of Petroleum Engineering,China University of Petroleum(East China),Qingdao,266580,Shandong,China

National Key Laboratory of Deep Oil and Gas,China University of Petroleum(East China),Qingdao,266580,Shandong,China

Oil and Gas Engineering Research Institute(Tarim Oilfield Company),China National Petroleum Corporation,Tarim,841000,Xinjiang,China

展开 >

国家自然科学基金国家自然科学基金China University of Petroleum(East China)China University of Petroleum(East China)

519743525228810120180000252019000011

2024

10.1016/j.petsci.2023.09.010

石油科学(英文版)
中国石油大学（北京）

石油科学(英文版)

EI
影响因子：0.88
ISSN：1672-5107
年,卷(期)：2024.21(2)
  • 1