Thermal oil recovery is a special technique belonging to Enhanced Oil Recovery (EOR) methods and includes steam flooding, cyclic steam stimulation, and in-situ combustion (fire flooding) applied especially in the heavy oil reservoirs. Starting 1970 in-situ combustion (ISC) process has been successfully applied continuously in the Suplacu de Barcau oil field, currently this one representing the most important reservoir operated by ISC in the world. Suplacu de Barcau field is a shallow clastic Pliocene, heavy oil reservoir, located in the North-Western Romania and geologically belonging to Eastern Pannonian Basin. The ISC process are operated using a linear combustion front propagated downstructure. The maximum oil production was recorded in 1985 when the total air injection rate has reached maximum values. Cyclic steam stimulation has been continuously applied as support for the ISC process and it had a significant contribution in the oil production rates. Nowadays the oil recovery factor it’s over 55 percent but significant potential has left. In the paper are presented the important moments in the life-time production of the oil field, such as production history, monitoring of the combustion process, technical challenges and their solving solutions, and scientific achievements revealed by many studies performed on the impact of the ISC process in the oil reservoir.

The presence of gas hydrates in natural gas extraction, transport and storage facilities, creates problems related to the blocking of flow pores in the productive layer, the clogging of pipelines and especially the increase in the delivery and pumping pressure of natural gas. This aspect usually leads to damage to oil structures by damaging them and especially by stopping gas supplies. The present work presents the history of the identification of natural gas hydrates present in nature as well as their nucleation conditions. Also, following the laboratory determinations, two new correlations could be made to indicate the pressure and temperature at the beginning of the nucleation of gas hydrates, starting from the determination of their specific gravity. The new correlations were compared with the laboratory data and with the existing correlations in the specialized literature, the results being close. Also, based on the observations of the formation of gas hydrates of some gases with a specific density between 0.6 and 1.0, it was possible to analyze the laboratory data with those obtained after running a new correlatios.

The exploitation of wellbore condensate deposits must be carried out in such a way that both water and condensate from the productive layer are not entrained during extraction. That is precisely why the article analyzes the effect of the density of perforations of the productive layer on the amount of extracted gas. The effect of the area affected by the drilling on the produced gas flow is also studied. After 50 years since the first use of the mechanical realization of the perforations of the productive layers of the gas wells, there is little data regarding the influence of the perforation geometry of a gas well, namely the way of communication between the production layer and the borehole, on its production. The aim of this paper is to simulate the operation of the well for different values specific to the drilling mode, highlighting its production. The problem is addressed by nodal analysis. The numerical simulators were used to simulate the flow of the mixture through the layer-well system and respectively through the mixture pipe.

The paper presents the experimental research results which the Romanian crude oils type B were subjected to. Tests conducted in laboratory environment aimed determination of crude oils rheological parameters and also identification of rheological behaviour models. Experiments, conducted at different temperatures, led to rheological behaviour models characteristic of non-Newtonian fluids. The established rheological relations help to better understanding of tested fluids so we can know either their behaviour or how we could impose their behaviour according to our needs.

"Many reservoirs comprised of relatively young sediments are so poorly consolidated that sand will be produced along with the reservoir fluids unless the rate is restricted significantly. The mathematical modelling of the flow of the sanded well uses the continuity equation written in cylindrical coordinates, Darcy's law admitting its availability and the solutions of these equations obtained for the boundary conditions in the case of a crude oil well that produces sand floods. In this article we have created a numerical model based on the variation of fluid flow from the productive layer, depending on the pressure drop between the productive layer and the wellbore, as well as the permeability of the layer. As a function of the flows extracted from the well, we rewrote the flow variation equations as polynomial relations of order 5, the error being a maximum of 0.04%. After determining the flow through the two relationships and confronting the reality in the field, the article confirms the type of flow through sand."