Tag Archives: permeability
In recent years, around the world there is deterioration in the structure of hydrocarbon reserves. Many oil companies are forced to take measures to increase the flow of oil to the producing wells. The most popular method is the method of hydraulic fracturing. One of the key characteristics of the effectiveness of hydraulic fracturing is the conductivity of the resulting fracture.
Practice has shown that there are a number of factors negatively influencing the fracture conductivity, one of which is the formation of a filter cake on the fracture surface, which can lead to a significant reduction in well production rates. In this connection it is necessary to conduct laboratory studies to assess the impact of the magnitude of the filter cake on the conductivity of the fracture.
During fracturing operations fracturing fluid in the fracture is under much greater pressure than in the reservoir, so it leaks and breaks the seam. However, since the cross linked guar molecules are too large and can not enter into the pore matrix, the polymer forms a dense cake on the fracture surface. Furthermore, when after the fracturing operation the pressure is reduced, the crack closes creating a tight proppant packing. When cracks close additional displacement of water from the formation of the polymer network occurs, resulting in even more increased concentration of the polymer. If the polymer remains undisturbed, the super viscous gelatinous mass is formed blocking the pore space of the fracture.
This article discusses a negative influence factor on fracture conductivity – the formation of a filter cake on the surface of the crack, which can lead to a significant decrease in well production rates. Also, the technique of calculating the coefficient of instantaneous loss and wall-building coefficient. Were obtained according to changes in recovery coefficient, coefficient of instantaneous loss and wall-building coefficient from permeability of a core.
AN APPROACH FOR FRACTURE ZONES IDENTIFICATION BASED ON SEISMIC ATTRIBUTES ANALYSIS, SHELYAUR AREA, TIMAN-PECHORA BASIN
Oil and gas industry has reached a stage when most traditional porous type reservoir, developed to near with depletion level. Thus, main attention is increasingly paid to the reservoirs, where porosity and permeability are presented by a system of natural fractures. This trend has given an incentive to grow in research of various methods for natural fractures systems identifying and analyzing as well as subsequent related to it permeability prediction. Study and prediction of natural fracture systems from seismic data is a difficult and actual challenge, because this can significantly influence the choice of oil field development strategy. At present, a wide range of seismic attributes is developed, which can help engineers perform such analysis, but they have limitations with size of structures that could be recognized on traditional seismic resolution, and from the point of view of their cost. The proposed method of multi-attribute data analysis through orthogonal decomposition, developed by I. Priezzhev, can be an effective approach to the study of fracture corridors, and the calibration with real data showed high reliability of the results. Within the study area zone with high anomalies content were identified that can be related with tension stress in the formation, which is often associated with naturally fractures of rock. The results of this study can be used in adjacent areas, where a large amount of data for calibration exists, for predicting the high permeability zones.
ANALYSIS OF THE INFLUENCE OF GEOLOGICAL AND TECHNOLOGICAL PARAMETERS OF WELLS AND HYDRAULIC FRACTURING ON ITS EFFICIENCY
Today hydraulic fracturing jobs are quite frequently performed on wells in the West Siberia and the Volga-Ural basins. Widespread application of hydraulic fracturing technology shows its significantly varying efficiency. The geological and engineering aspects of hydraulic fracturing have been analyzed to identify the key parameters of wells and of the fracing process which have the greatest impact on the efficiency of this technology. Geostatistical analysis was used to confirm the dependency of fracing efficiency on the identified well parameters. This analysis involved grouping of wells by geotechnical criteria and engineering characteristics of the fracing process by means of cluster analysis. The performance of 33 wells from nine fields from January 2010 to December 2011 has been analyzed. The fracing was performed on the Devonian clastic reservoirs of Pashiysky and Kynovsky Formations. The geology and reservoir properties of these productive formations, as well as the PVT properties of the in-situ fluids vary considerably. Well parameters also vary in a wide range. Hydraulic fracturing jobs are frequently performed on new wells to improve their productivity. A case study of such fracing job on a new well from the Kitayamskoe oil field, common in the Colgano-Borisovskay Depression, has been considered.
It is known that in a situation where a horizontal well is not fulfilling the project purpose to develop oil reserves, mining companies carried out a set of actions for the stimulation. To him in particular applies to hydraulic fracturing, held in the horizontal well by different technologies. The urgency of predicting the effectiveness of hydraulic fracturing in the horizontal well associated with the practical results of its application. The article studies comparison of different models of efficiency of a formation hydraulic fracture depending upon a well location in the system of production and injection wells. The studies resulted in getting very close showings of oil removals and essentially different showings of pressure. So, it was suggested to carry out modeling of a formation hydraulic fracture on the basis of an alternative model. The article considers substantiation of choice of a well-known software package under the name of "Tempest-More" for hydro-dynamic modeling in order to assess effect of a formation hydraulic fracturing, carried out in various conditions, on the amount of oil recovery. The article also presents methods of initial data preparation for numerical studying (properties of oil, gas, water, phase permeability) as well as technological criteria for production and injection wells. Using a formation model, studies effect of a formation hydraulic fracturing technology on amount of oil resources recovered from a deposit by means of application of numerical method and with account of operation of nearby production wells. It is proved that effect of a formation hydraulic fracturing, after being implemented in a well, breaks and affects showings of the nearby wells, where volume of oil removals decreases insufficiently, while volumes of produced water increase, thus minimizing economic efficiency of water removal technology.