A Comprehensive Evaluation Method for Cement Slurry Systems to Enhance Zonal Isolation: A Case Study in Shale Oil Well Cementing

Xiaoqing Zheng, Weitao Song (), Xiutian Yang, Jian Liu, Tao Jiang, Xuning Wu and Xin Liu
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Xiaoqing Zheng: CNPC Daqing Drilling Engineering Company Limited, Daqing 163511, China
Weitao Song: Petroleum Engineering School, Southwest Petroleum University, Chengdu 610500, China
Xiutian Yang: CNPC Daqing Drilling Engineering Company Limited, Daqing 163511, China
Jian Liu: Petroleum Engineering School, Southwest Petroleum University, Chengdu 610500, China
Tao Jiang: CNPC Daqing Drilling Engineering Company Limited, Daqing 163511, China
Xuning Wu: Petroleum Engineering School, Southwest Petroleum University, Chengdu 610500, China
Xin Liu: CNPC Daqing Drilling Engineering Company Limited, Daqing 163511, China

Energies, 2025, vol. 18, issue 15, 1-19

Abstract: Due to post-cementing hydraulic fracturing and other operational stresses, inadequate mechanical properties or suboptimal design of the cement sheath can lead to tensile failure and microcrack development, compromising both hydrocarbon recovery and well integrity. In this study, three field-deployed cement slurry systems were compared on the basis of their basic mechanical properties such as compressive and tensile strength. Laboratory-scale physical simulations of hydraulic fracturing during shale oil production were conducted, using dynamic permeability as a quantitative indicator of integrity loss. The experimental results show that evaluating only basic mechanical properties is insufficient for cement slurry system design. A more comprehensive mechanical assessment is re-quired. Incorporation of an expansive agent into the cement slurry system can alleviate the damage caused by the microannulus to the interfacial sealing performance of the cement sheath, while adding a toughening agent can alleviate the damage caused by tensile cracks to the sealing performance of the cement sheath matrix. Through this research, a microexpansive and toughened cement slurry system, modified with both expansive and toughening agents, was optimized. The expansive agent and toughening agent can significantly enhance the shear strength, the flexural strength, and the interfacial hydraulic isolation strength of cement stone. Moreover, the expansion agents mitigate the detrimental effects of microannulus generation on the interfacial sealing, while the toughening agents alleviate the damage caused by tensile cracking to the bulk sealing performance of the cement sheath matrix. This system has been successfully implemented in over 100 wells in the GL block of Daqing Oilfield. Field application results show that the proportion of high-quality well sections in the horizontal section reached 88.63%, indicating the system’s high performance in enhancing zonal isolation and cementing quality.

Keywords: shale oil; cementing; cement sheath integrity; mechanical properties; optimization of formulation (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: 2025
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