Petrovietnam Journal

Enhanced oil recovery (EOR) in fractured granite basement reservoirs: Non-chemical solutions for the Bach Ho field

Phung Dinh Thuc — 2025-02-25

Fractured basement reservoirs - especially the granitic basement of the Bach Ho field in the Cuu Long basin - exhibit distinct structural features including low permeability and porosity, high temperature, complex fracture system... These conditions pose significant challenges for enhanced oil recovery (EOR) strategies, as chemical EOR methods are typically ineffective.
This study synthesizes and analyzes the characteristics of oil accumulations in fractured basement reservoirs, identifies persistent challenges encountered during production from such reservoirs, and evaluates the feasibility of physical and mechanical EOR methods tailored to basement formations. Based on these analyses, it proposes technically feasible solutions to enhance oil recovery at the Bach Ho field under the current stage.

Evaluation of field trials of an in-situ gel- forming chemical system for water shut-off in production wells at the West-Khosedayu field and it’s application potential in Vietnam

Nguyen Tri Dung — 2025-02-25

This paper presents the research results and field trials of an in-situ gel-forming chemical system for water shut-off conducted at the West-Khosedayu field. The research was carried out by VNIIneft and field trials were implemented by Rusvietpetro Joint Venture Company. During the research phase, VNIIneft selected and optimized a chemical system with a gelation time of up to 70 - 80 hours at reservoir temperature, specifically suitable for selective plugging of high-permeability channels that serve as primary water conduits in fractured carbonate formations. Based on these research outcomes, during the period of 2019 - 2023, Rusvietpetro conducted 30 field trials in the D3fm-III reservoir, achieving a success rate of 96.7%. Each well was injected with an average of 500 m³ of chemicals into the zone below the open-hole interval. Results showed that average water cut decreased from 86% to 70%, oil production increased by an average of 20.3 tons/day/well immediately after treatment and sustained at 17 tons/day/well thereafter. The cumulative incremental oil production reached 179,719 tons. The success of this technology was attributed to three key factors: (i) development and selection of a gel-forming chemical system with properties tailored to reservoir conditions, (ii) accurate identification of target zones/wells based on geological and production criteria, and (iii) optimization of the injection and well treatment procedures.

Research and application of “cement basket” technology in water shut-off without jack-ups: Technical and economic evaluation on production objects at Block 09-1, Cuu Long basin

Nguyen Quoc Dung — 2025-02-25

As of now, traditional oil fields operated by Vietsovpetro, such as Bach Ho and Rong, have entered the late stage of production, characterized by declining reservoir pressure and high water-cut levels exceeding 60%. This poses significant challenges for reservoir management, field operations, and production optimization. Sustaining output from these mature fields requires the application of effective and cost-efficient technical solutions. For that purpose, Vietsovpetro has deployed the cement basket technology for water shut-off without the need for drilling rigs, enabling better control of water-cut and contributing to enhanced oil recovery.
This paper presents the application result of the cement basket technology for water zone isolation without jack-ups at Vietsovpetro, encompassing the full process from theoretical basis study, candidate evaluation to field implementation. It also analyzes the technical complexities encountered during the first pilot test for fractured basement reservoirs, evaluates the technical and economic effectiveness of the method, and draws lessons learned to improve the technological performance, future scalability and broader applicability of the technology.

Petrographic characteristcs and fractured reservoir potential of the pre-tertiary basements in Dai Hung field, Block 05-1(a), Nam Con Son basin

Nguyen Xuan Phong — 2025-02-25

The fractured granitoid basement reservoir in Vietnam is one of the most distinctive reservoirs in the world, accounting for 82% of the total country’s oil production [1]. The Dai Hung oil field locates in Block 05-1(a) on Mang Cau High in Nam Con Son basin, where the pre-Tertiary basement was formed contemporaneously with the basement of the Cuu Long basin and magmatic Dalat zone. In the Dalat zone, magmatic intrusives belong to the suites of Dinh Quan, Deo Ca and Ca Na (Ankroet). The presence of an active petroleum system in the Nam Con Son basin is proven by a series of oil and gas fields. In this system, Oligocene and Early Miocene effective source rocks are matured, generating hydrocarbons that are charged to clastic reservoirs. The basement in the Dai Hung field, mainly composed of granodiorite interbedding with dykes, were penetrated by 24 wells with basement section drilling depths ranging from 10 m to 1043 m. Seismic and well data reveal two major fracture systems striking NE-SW and sub E-Wn. This study aims to elucidate the reservoir potential of the fractured granodioritic basement in Dai Hung field.

Study on the formulation of additives to improve elasticity, tensile strength, and crack propagation resistance of the cement sheath in oil and gas well cementing

Nguyen Thi Kim Dung — 2025-02-25

This study focuses on developing a composite additive system to improve the elasticity, tensile strength, and crack propagation resistance of the cement sheath in oil and gas well cementing. The primary materials used are nitrile rubber particles and alkali-resistant glass fibers, selected based on their appropriate particle size distribution and fiber dimensions that minimally affect the rheological properties of cement slurry.
As a result, the study successfully established a composite additive system comprising 0.75% alkali-resistant glass fibers and 6 - 6.5% nitrile rubber particles that effectively enhances the elasticity, tensile strength, and crack propagation resistance of the cement sheath in oil and gas cementing. After surface modification with dispersing agent, the composite additives demonstrated the ability to increase the tensile strength-to-elastic modulus ratio, enabling the cement sheath to better withstand long-term stress in downhole oil and gas well environments. Additionally, the impact strength of the cement sheath containing the composite additives was significantly higher compared to samples without additives.

Development of heat-resistant ultra-fine cement for well cementing to improve oil and gas recovery efficiency

Phan Van Minh — 2025-02-25

In the oil and gas industry, squeeze cementing is a widely adopted technique to repair cement sheath defects, particularly to eliminate the pressure differentials between the casing annulus and the flow outside the casing. The ability of mortar to penetrate fracture networks and micro-sized pores depends significantly on the particle size distribution of the binder used. Replacing conventional well cement with ultra-fine ground cement for squeeze applications is an effective solution to improve the quality of the cementing process. This study focuses on developing a heat-resistant ultra-fine cement (d50 ≤ 6 μm), stable up to 160°C and non-shrinkage within the temperature range of 50 - 160°C, from primary feedstocks such as Portland cement clinker, phosphate slag, and silica sand. The raw materials were mixed to ensure thermal stability and shrink-resistance criteria, aiming to identify the most feasible optimal formulation for producing this ultra-fine slag - Portland - silica cement.
The evaluation of the cement powder indicates that the selected components meet the particle-size requirements (d50 ≤ 6 μm; d95 ≤ 16 μm). The assessment of the mortar and hardened cement derived from the ultra-fine slag – Portland - silica cement exhibited volumetric expansion at both low (< 76°C) and high (> 76°C to 160°C) temperatures, with expansion levels meeting sulfate durability and shrink resistance standards. This confirms that the cement is entirely shrinkage-free within the temperature range of up to 160°C. Additionally, the compressive strength achieved was 1231 - 1413 psi under conditions of 120 - 160°C and a pressure of 210 atm, well above the ≥ 500 psi threshold specified for oil well squeeze cementing. The research team successfully identified an optimal blend design and validated the practical feasibility of producing a heat-resistant ultra-fine slag - Portland - silica cement for squeeze cementing applications.

Application of real-time dynamic simulation for safe and efficient operation of the Nam Con Son two-phase pipeline

Bui Tien Dung — 2025-02-25

This paper presents the real-time dynamic simulation solution applied by Nam Con Son Gas Pipeline Company (NCSP) to ensure the safe and efficient operation of the 371 km two-phase pipeline (gas and condensate). The simulation software MSI, developed based on the OLGA platform, has been used by NCSP to monitor liquid holdup, predict operating scenarios, detect leaks, and optimize pipeline operations. The successful use of this solution has enabled the delivery of nearly 110 billion m³ of gas and 2.7 million tons of condensate over the last 22 years, contributing significantly to the national energy security and laying the foundation for digital transformation in Vietnam's gas industry.

Petroleum and medical technologies: Collaboration potential and cross-industry applications

Phan Ngoc Trung — 2025-02-25

This paper analyzes the technological similarities between the oil and gas and medical industries. Although these two fields pursue different purposes, one supplying energy and the other caring for human health, they both rely on advanced technologies to explore, intervene in, and manage complex systems. These similarities are evident across various aspects, including: non-invasive imaging technologies (3D/4D seismic and ultrasound/MRI/CT), sampling techniques for characterization (core drilling and biopsy), minimally invasive intervention tools (directional drilling and endoscopic surgery), sensor and automation technology (ROVs and surgical robots), the application of advanced materials for harsh environments, and stringent risk and safety management protocols.
The paper particularly emphasizes the role of big data analytics and artificial intelligence (AI) as important catalysts, optimizing processes from reservoir forecasting and production optimization to disease diagnosis in medicine. Recognizing these technological convergence points of the two fields opens up potential for interdisciplinary collaboration, promoting innovation to create breakthrough developments for both the energy and medical sectors.