Applying the methods of enhanced oil recovery (EOR) for oil and gas fields has always many risks of economic and technology because EOR projects are influenced by many characteristic factors of the reservoir such as structure of reservoir, reservoir formation, geological properties, parameters of reservoir engineering, production technology to EOR application. Some EOR methods have been successfully applied in the world, but when these methods conduct in specific reservoir with different geological characteristics, tight production conditions have resulted in failures and ineffective economic, even caused dreadful aftermath to be handled in operations. Researches, evaluations and EOR applications in Vietnam are limited and only carried out on a laboratory scale. Therefore, the ability to be applied the EOR modern technology with a large scale or full field still faces many difficulties and the feasibility of projects is not high enough. The authors have been analysed all EOR projects successfully that applied many oil and gas fields in the world and then building EOR database. Based on EOR database, a study has been conducted on statistical analysis to build EOR screening criteria for reservoir parameters from past to now. The study also combined in-depth analysis algorithms such as Fuzzy, K - mean, PCA Artificial Intelligence to screen the optimal EOR method for sandstone reservoirs of Cuu Long Basin.

In the oil and gas exploitation or geo-thermal energy exploitation industries, wellbores can be drilled at great depths where the formation would be hot and saturated. In such case, a large temperature difference between the rock mass and drilling fluid can occur and cannot be ignored. During drilling the wellbores, thermic, hydraulic and mechanical phenomena appear simultaneously and interact with each other within the rock. This study presents the analysis of stress state around the wellbore located in saturated hot rock based on the fully thermo-hydro-mechanical behavior model of the rock mass by the finite element method. Two scenarios involving thermal conditions at the well wall are taken into account, i.e. the drilling fluid temperature is lower or higher than the formation temperature so-called the cases of “cooling” and “heating”, respectively. In this study, the influence of some thermic, hydraulic and initial stress field parameters of the rock mass on the stress state around the wellbore was also clarified. The obtained results showed that, in the cooling case, the well wall may be destabilized by fracture failure while in the heating case this would be collapse failure. The maximum points of tangential and axial stresses appear at the same locations for the two scenarios. In addition, the thermal expansion coefficient, the initial shear stress in the rock mass greatly affect the stress state around the wellbore whilst the permeability of the formation does not influence on the stresses on the well wall but only on the stresses inside the surrounding formation.

In offshore production of oil and gas, transporting products by subsea pipeline always has potential risks affecting the efficiency of the transportation process. For the Diamond oilfield, the process of gathering products and transportation is carried out according to a closed scheme in which the exploited products are preliminarily treated. The separated oil is transported to FPSO Ruby - II while the separated gas passed through the air compressor to increase pressure and then used for gaslift production. In fact, the oil produced at the Diamond oilfield has a high paraffin content, which causes difficulties during transportation. Therefore, the study on flow assurance to ensure the transportation of oil and gas from the Diamond oilfield to the FPSO Ruby - II is imperative. This paper presents the results of the research on flow assurance to maintain the safety of the transportation basing on the analysis of field data and the capability of the current subsea pipeline in comparison with the data gained from models carried out with OLGA software. The results show that the rate of wax deposition at normal steady state condition is relatively low. In addition, the thickness of wax deposition build - up is relatively small by simulation results. However, due to low temperature of transported oil which is lower than pour point temperature, a freeze layer will form on the surface of the pipeline. Therefore, regular pigging is considered the most effective way to remove wax.

Mechanical equipments such as pumps, air compressors, etc. play an important role in the production, processing and transporting oil and gas since every single equipment, serves different functions. For oil and gas transportation system, pump is an essential mechanical device used to pump and transport the product. In order to promote technical features as well as high working efficiency, it is important to ensure that these devices always work the most efficiently in the best technical conditions. The application of modern scientific and technical advances to the maintenance and operation of mechanical equipment in general and pumps in particular will help to reduce the risks and bring economic benefits to the operators. This paper, therefore, presents results of the research on the application of artificial intelligence (AI) in diagnosing common failure of Condensate pums at Hai Thach - Moc Tinh field basing on analysis of field data which help to improve the efficiency of gas condensate transportation. The results helped to predict and warn early the possible failures to the Condensate pums at Hai Thach - Moc Tinh field. Results of the research can be applied to other equipment devices working in the same conditions during oil and gas production process in Vietnam.

Wellbores are usually located in saturated geological layers. The determination of pore water pressure field around the wellbore is necessary during the design calculation and drilling stages. This paper presents analytical approach to determine the pore water pressure field around a horizontal wellbore at deep geological layer that exhibits heterogeneous, isotropic or transversely isotropic behavior. Thus, the wellbore is considered to be in an infinite medium. The pore water pressure at the well wall, equal to the drilling mud pressure, together with the pore water pressure at infinity is assumed to be constant. The closed-form solutions are based on the theory of fluid transport in porous medium and the conformal mapping technique of the complex variable method. The closed-form solutions are established with the condition of transient fluid flow for the case of isotropic medium and with the condition of steady state fluid flow for the case of transversely isotropic medium. The accuracy of the closed-form solutions is validated by numerical solutions based on the finite element method. The obtained solutions can be used as tools to determine quickly and accurately the pore pressure field around the horizontal wellbore, which serves to evaluate the stability of the well wall in preliminary design of the wellbore, as well as the amount of water inflow into it. Furthermore, the closed-form solutions are also considered as reference solutions to evaluate the accuracy and reliability of numerical models.