جستجوی مقالات مرتبط با کلیدواژه "ضریب پوسته" در نشریات گروه "مهندسی شیمی، نفت و پلیمر"

Permeability, skin factor, and wellbore storage coefficient are three essential parameters for well and reservoir. Moreover, well testing is the conventional method for determining these parameters. In this method, pressure data are plotted versus time in semilogarithmic and logarithmic scales, and specified relations determine well test parameters. In this study, a new approach is introduced to obtain well test parameters using artificial intelligence. First, using endpoints related to two real wells, pressure data are produced by reservoir simulator software. Because the data have a lot of noises, the additional data are removed, and analyzing the data is more comfortable. Then, with the combination of a genetic algorithm and the Levenberg Marquardt algorithm, the basic parameters of the reservoir have been calculated. In the last step, the pressure data are entered into standard software, and their values are calculated. Finally, the combined algorithm with excellent accuracy has been able to calculate these parameters in comparison with the conventional Saphir 4.10 well testing software.

It is essential to understand gas condensate reservoir behaviour correctly. A special way of meeting this requirement is taking the advantage of well testing analysis. The simultaneous presence of condensate and gas in a reservoir alters the gas relative permeability around a production well, which influences the well test responses. Moreover, another parameter which alters this behavior more is non-Darcy flow of fluid around the well. Furthermore, some factors like the rate of production and type of gas condensate reservoirs play a crucial role in condensate formation. These factors have important impacts on the formation of condensate. In other words, they add an additional skin factor caused by the formation of condensation around wells. The aim of this study is to consider the correlation between production rate and skin factor. Moreover, the method is using data obtained from a compositional reservoir model to investigate the transient behavior around the producing well and reinterpreting the results of the reservoir model during well test analysis. Finally, in this way, by creating different scenarios of production and build-up tests, the effects of downward and upward trends of the production rate on the condensate formation and its effect on the well-test data have been examined by us. Some weight functions for representing the production rate changes versus skin factor are developed as well.

Stress dependent permeability is a great problem in petroleum engineering and natural fractured reservoirs. Permeability in a fractured porous medium is mainly controlled by the geometry and interaction of the pores and fractures as well as stress state. Interaction between stress and permeability in jointed reservoirs is a crucial factor during different stages of life of a reservoir such as assessment, productivity and management. Also, reduction in reservoir pressure significantly influence on the reservoir permeability. In this study, it is intended to find the relationship between the stress sensitivity and production rate. For this purpose, distinct element code is used to develop numerical modeling of a reservoir to evaluate the relationship between stress sensitivity and productivity rate. The results of numerical simulations indicated that with increasing the bulk modulus of rock joints, the skin factor increases and consequently the well productivity decreases.

Due to the failure of some stimulation operations which have applied on carbonate reservoirs of Darian’s formation of Ahwaz oilfield, in order to improvement in formation damage and increase in permeability, the effect of several acids (HCL with 10%, 15% and 28% dosages) was evaluated by comprehensive research on a candidate well. Moreover, the porosity type of this formation was evaluated due to another research by using core analysis tests, FMI Tool reports and well testing analysis by PanSystem v3,4 software. According to the results, high concentration of acid, it is not always in tune with its increasing performance and the optimum concentration on the conditions of each reservoir and oil wells should be consider. Consequently, using HCL 15% is creating the best condition to this stimulation process. Success of this operation is also clear due to decreasing in skin factor of 5 to -4.45. Since there is a disagreement between the reservoir engineers regards to the being single or dual porosity of Darian’s formation, notwithstanding of its carbonate reservoirs, being single porosity of this formation is more logical, according to the evaluation’s results.

Forces of drilling bit cause a lot of changes in rock characteristics, especially in rock mechanical properties.Changes of reservoir lithology cause pressure drop around wellbore during production procedure. Routin tests were carried out in all the wells after completion and unexpectedly high Darcy skins were estimated from the test data for all of the wells. In order to prepare prevention and remediation plans, it is crucial to understand the source of the skin. Determination of skin factor due to changes in drilling process (force and tension of drilling bit) around wellbore is very critical. The main purpose of determination of drilling bit effects is to control and prevent formation damage around wellbore. A lot of research has been performed regardig skin factor around wellbore. However, given the effects of drilling process such as stress on skin factor, attempt has been done todetermine the effects of these parameters on skin factor around wellbore. The results of these analyses prove effective and controllable influence of drilling and skin factor around wellbore. The research shows controlling and reducing of skin factor around wellbore by appropriate planning of drilling and drilling bit. Another aim of this research is the explanation of the relation among different processes in petroleum industry to prevent formation damage. By careful examination of the structure before drilling planning and drilling bit selection, formation damage will reduce dramatically and destructive pressure drop in reservoir can also be prevented.