Evaluation and treatment of casing pressure in injection/production wells of SQ underground gas storage

Oil&Gas Technology Research Institute of Huabei Oilfield Company, CNPC Renqiu, Hebei, China

^*a Corresponding author: yjy_wsq@petrochina.com.cn,
^b cyy_rongw@petrochina.com.cn,
^c cyy_yangxp@petrochina.com.cn,
^d cyy_panz@petrochina.com.cn,
^e cyy_liulw@petrochina.com.cn,
^f cyy_yk@petrochina.com.cn,
^g cqk_zhangyi@petrochina.com.cn,
^h cyy_lhy@petrochina.com.cn

Abstract

The evaluation and management of sustaining casing pressure (SCP) in injection/production wells of underground gas storage(UGS) is an important part of the wellbore integrity. SQ underground gas storage has experienced ten complete injection/production cycles, which puts forward high requirements on management of well integrity. At present, there are different degrees of SCP of injection/production wells of SQ UGS, which seriously threatens the safety of the UGS. This paper analyzes casing pressure in different injection/ production stages and working conditions of injection/production wells, combined with API RP 90-2, NORSOK, ISO/TS 16530-2, SY/T5724-2008 standards. We established an SCP evaluation process and a static and dynamic SCP risk evaluation system, and then proposed a four-level risk control mode for UGS injection/production wells. We formulated a production management method for wells with SCP, constantly improved the operating environment of UGS wells. We managed the injection /production wells with SCP higher than the MAWOP, especially the annular leak problem of well S7. The SCP treatment achieves effective plugging, guarantees the integrity of the injection /production wells, and achieves good repair effect, which has certain guiding significance for the evaluation of the integrity of the injection/production wells of the UGS and the management of the SCP.