Petrovietnam Journal

Application of machine learning to decline curve analysis (DCA) for gas-condensate production wells with complex production history due to add-on perforation of new reservoirs

Huu Hai Ngo — 2023-12-25

For every oil and gas operator, DCA plays an essential role since it provides crucial information for production planning and reserves estimation. DCA is the analysis of the decline in production rate or pressure over time, which can be done by fitting a curve through production or pressure historical data points and making a forecast for the well based on the assumption that the same declining trend will continue in the future. However, the conventional DCA method has been shown to have some limitations. On the other hand, machine learning has been vigorously and extensively researched in the last decade; its applications can be found in every aspect of life as well as in the oil and gas industry. Therefore, it is the ideal time to study the application of machine learning to DCA, to complement this important analysis. In this case study, machine learning was used to predict the decline of wellhead pressure, thereby determining well life as well as estimating reserves. The method was applied to 2 wells with very complex production histories due to add-on perforation of new reservoirs. The prediction was verified to have high reliability by comparison with dynamic modeling results.

Application of machine learning to predict the time evolution of condensate to gas ratio for planning and management of gas-condensate fields

Huu Hai Ngo — 2023-12-25

One of the most important parameters for the evaluation, forecast, and management of gas-condensate fields is the evolution of the condensate to gas ratio (CGR) over time. This parameter tends to decrease as reservoir pressure declines. In the conventional approach, gas and condensate samples are collected at the beginning of production and periodically later to conduct laboratory experiments on composition, CGR, and fluid properties. However, sample collection, transportation, and analysis require a lot of time and effort and could be very expensive. Likewise, dynamic models are also frequently used to predict CGR over time. However, these models could include many uncertainties due to ambiguous input data, including reservoir structures, fluid phase interaction, and reservoir property distribution. Therefore, the application of machine learning to predict the time evolution of CGR in this research could be a new and effective approach to supplement conventional methods.

Integration of geological and well log and geomechanical modeling toward a safe mud weight for wellbore stability: A case study of Ruby field, Blocks 01&02, Cuu Long basin

Van Hoang Nguyen — 2023-12-25

There is a high density of drilled wells in Blocks 01&02 which is a part of the Cuu Long basin. The geological settings of this area have undergone a complicated evolution, resulting in heterogeneous lithology and variable stresses. Consequently, drilling activities in the Ruby oil field have faced numerous challenges, such as stuck pipe, gas kick, mud loss, and even lost well, etc. leading to substantial time and financial setbacks. It is essential to thoroughly understand the geomechanical characteristics of Ruby field to ensure safe operation and optimize drilling. In this paper, several downhole geophysical data sets such as wireline logging data as gamma ray (GR), density log (RHOB), neutron (NPHI), compression/shear sonic travel time (DTC/DTS), image formation log (FMI), pressure test (MDT) and leak of test (LOT, XLOT) are used to construct the 1D geomechanical model. The objective of this modelling is to compute parameters of pore pressure, vertical stress, horizontal stress, elastics properties, rock strengths. Then, these parameters are used to analyze the wellbore stability and to recommend appropriate drilling mud weights for the wells under study. This analysis can subsequently be extended to cover the entire Ruby oil field for the future drilling operations to enhance overall safety and efficiency.

Geomechanics applied to the petroleum industry: Wellbore stability, sand production, and hydraulic fracturing

Van Hung Nguyen — 2023-12-25

This article introduces three applications of geomechanics in oil and gas industry, encompassing wellbore stability analysis, hydraulic fracturing, and sand production. In this paper, we reviewed three commonly used applications involving transforming stress values from the in situ coordinate system to the wellbore centric coordinate system, which have been published in the previous studies. Subsequently, various failure criteria are applied to these three geomechanical problems. First, wellbore stability analysis involves six distinct scenarios across different oil reservoirs. The results obtained enable the selection of appropriate drilling mud densities to prevent collapses and instability of wellbore. Second, regarding sand production modeling, three oil fields are presented as examples. The results consistently indicate instances of sand production under various well production conditions. Finally, the application of geomechanics in hydraulic fracturing is illustrated. The findings distinctly illustrate the evolutionary pattern of fracture dimensions, highlighting a consistent trend in fracture length development. Notably, the expansion phase of the fracture exhibits a rapid onset during the initial stages, followed by a transition into an exceedingly gradual propagation state.

Porosity cut-off values evaluated by classifying reservoir rock types from cores data. A case study for Triassic reservoir T1, Blocks 433a&416b, Algeria

Khanh Xa Ngo — 2023-12-25

This paper introduces the method to determine the porosity cut-off values by classifying rock types from cores data based on permeability cut-off value by 1 mD (for sandstone reservoir with oil). The purpose of this method is to calculate net pay reservoir more precisely for estimating hydrocarbons initially in place and building static models. Normally, the cut-off values of porosity are defined on a cross-plot of porosity versus permeability obtained from core data. However, the results of petrophysical analysis are not consistent with DST results. There are some wells with reservoir net pay of several meters, but the DST does not deliver flows. The application of a new method determining the porosity cut-off values on T1 reservoir shows the reservoir net pay is consistent with actual data of the field.

Method for estimating the probability of geological success: A case study of the HRA-E prospect, Block 106, northern Song Hong basin

Dang Hung Tran — 2023-12-25

Petroleum exploration and drilling represent fields fraught with inherent uncertainties, consequently, geological assessment is significantly important for precisely selecting prospects and well locations. The geological evaluation of prospective formations predominantly relies on 5 elements of the petroleum system including source, reservoir, seal, trap, and migration.
This article introduces globally applied geological assessment methods, and proposes an applicable methodology for exploration targets across regions with varying levels of available data. Applying this method of evaluating risk criteria for pre-Cenozoic carbonate objects of HRA-E prospect in Block 106 shows that the evaluation results align with the actual probability of success in drilling exploration activities in the region and could be extended to other projects within the Petrovietnam Exploration Production Corporation (PVEP).

A comprehensive technical assessment of well intervention operations across all PVEP’s projects (2017 - 2021 period) and recommendations for ongoing optimization

Ngoc Thanh Huy Nguyen — 2023-12-25

This article provides a summary and assessment of well intervention activities, including perforation (add-perf/re-perf), acid treatment (acidizing), water/gas shut-off (WSO/GSO), hydraulic fracturing (HF), and electric submersible pump installation (ESP) at oil and gas production projects that the Petrovietnam Exploration and Production Corporation (PVEP) has participated in investment, operation, and optimization during the period of 2017 - 2021. Based on this, the effectiveness of well interventions in increasing production and reservoir recovery is evaluated. Additionally, the article analyzes lessons learned and proposes directions for optimizing well interventions for the next phase.

Evaluating the digitalization capability and display of KPIs for two fertilizer plants of Petrovietnam

Minh Thuan Huynh — 2023-12-25

The study partially funded by the Vietnam Oil and Gas Group (Petrovietnam) assesses the infrastructure, OT/IT systems, and data handling at two fertilizer plants. Although well-equipped with automation control technology, the plants lack seamless integration, connectivity, and encounter limitations in communication between systems. To address these issues, the study advocates for the integration of digital technology, emphasizing its potential for enhancing efficiency, facilitating optimal management, and guiding strategic direction. Following an assessment of infrastructure, key performance indicator (KPI) system requirements, and data management, the study proposes an initial application of digital technology to link KPI displays. The outlined scope, initial costs, investment phases, and implementation schedule indicate a total initial investment of around VND 37 - 39 billion, accompanied by annual maintenance costs ranging from VND 3.7 to 4.1 billion. Expected economic and social benefits involve improved management at both Petrovietnam and plant levels through the KPI system, with an estimated energy cost savings of 1%, equivalent to roughly VND 44.6 billion. The project aims to position the fertilizer plants and Petrovietnam as leaders in technology, contributing to sustainability and enhancing their global industry reputation.

Petrovietnam leveraging its technology and services inherited from oil and gas operation into the construction and supply chain of offshore wind power

Hoai Nam Tran — 2023-12-25

In the era of global integration, there is a clear shift from fossil fuels to renewable energies across nations. The investigation and utilization of renewable energy sources, especially offshore wind energy, emerge as a pivotal area for energy companies and corporations.
The Vietnam Oil and Gas Group (Petrovietnam) is standing at the threshold of substantial opportunities and challenges in expanding its operational spectrum towards renewable energy with a particular focus on offshore wind power. This study analyzes Petrovietnam's inherent strengths and capabilities with the orientation and strategy to become a leader of the service supply chains for offshore wind power in Vietnam.

Fertilizer packaging companies of Petrovietnam toward circular economy

Vi Sa Tu — 2023-12-25

A circular economy is an economic system designed with the intention that maximum use is extracted from resources and minimum waste is generated for disposal... In the context of fertilizer packaging, manufacturers have been striving to produce green fertilizer bags which are recyclable, reusable and cost-efficient. When packages (both reusable and single-use) can no longer serve its function, the material should be circulated through recycling or composting. It is a matter of materials sciences (mono-material construction or material selection) and innovations in packaging formats (flexible packages, jumbo bags, sling bags, etc.) to make progress. Along with these, the sorting and collection infrastructure needs to be set up to keep products after use in a closed loop. As well, the economic attractiveness, incentives for stakeholders are essential to make the system work effectively.