Title: Optimised design and evaluation of cement slurry for HPHT well integrity in Basin X

Authors: Hai T. Nguyen; Khaled A. Elraies; Tarek Al-Arbi Ganat; Tu V. Truong

Addresses: Laboratory of Applied Physics, Science and Technology Advanced Institute, Van Lang University, Ho Chi Minh City, Vietnam; Faculty of Applied Technology, Van Lang School of Technology, Van Lang University, Ho Chi Minh City, Vietnam ' Department of Petroleum Engineering, Universiti Teknologi PETRONAS, Perak, Malaysia ' Petroleum and Chemical Engineering Department, Sultan Qaboos University, Muscat, Sultanate of Oman ' Drilling and Production Department, Faculty of Petroleum and Energy, Hanoi University of Mining and Geology, Vietnam

Abstract: This study presents the development and evaluation of a high-performance cement slurry specifically engineered for the complex high-pressure, high-temperature (HPHT) conditions of Basin X, offshore Vietnam. Unlike generalised HPHT slurry formulations in prior studies, this research addresses a region-specific challenge, incorporating a customised combination of silica-based stabilisers, synthetic retarders, and manganese tetroxide weighting agents to mitigate strength retrogression and ensure long-term well integrity. The slurry demonstrated exceptional performance, achieving a mixability rating of 4/5, stable rheological behaviour across temperature ranges (plastic viscosity of 50 cP; yield point of 20 lb/100 ft²), and fluid loss under 50 ml/30 minutes. It maintained thickening times suitable for placement even at elevated temperatures and reached compressive strengths of 474.1 psi at 12 hours and 931.5 psi at 24 hours. By addressing both operational risks and geological challenges unique to Basin X, this study delivers a tailored, field-tested slurry design that advances HPHT cementing practices and supports safe, reliable well operations under extreme subsurface conditions. [Received: October 4, 2024; Accepted: July 2, 2025]

Keywords: high-pressure; high-temperature; HPHT; slurry design; production liner; cement additives; strength retrogression; early setting.

DOI: 10.1504/IJOGCT.2026.153879

International Journal of Oil, Gas and Coal Technology, 2026 Vol.40 No.1, pp.1 - 17

Received: 03 Oct 2024
Accepted: 02 Jul 2025
Published online: 29 May 2026 *

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