Field development. Reservoir engineering. Production
This research is relevant as the development of world energy over the past decades is characterized by increased production and consumption of natural gas. One of the leading gas producing countries is Russia, which accounts for more than 25% of the world’s total gas production. In the Energy Program of the Russian Federation, by 2020, the planned volume of gas production will be 700 billion m3. The development strategy of the gas industry provides for the extraction of residual geological reserves. All these aspects are pushed to create new and effective technologies for gas preparation, as well as modernization of existing technological processes and equipment for gas preparation.
Every year, the role of gas in the global fuel and energy balance is becoming increasingly important. Thus, in 2002, global production amounted to approximately 2.800 billion m3. Of these, only 522 billion cubic meters of gas were produced by Russia’s Gazprom. The growth of gas production in Russia by 2005 was about 5%.
The state of the oil and gas industry is characterized by low automation, the use of obsolete and worn-out equipment, a decrease in gas production in exploited deposits, an ever-increasing remoteness of developing deposits, and so on. In conditions of increased competition from foreign producers, modernization of gas engineering and increasing the efficiency of gas production are vital for ensuring energy security and stable economic development of the country.
The article discusses the problem of exploitation of gas fields, at a late stage of development. The operation is complicated, because of the accumulation of condensation and formation water, a limited number of technological processes are used, as a result of which the productivity of the wells decreases or irreversible gas losses occur during process blowdowns.
In this article the main problem of gas industry is shown. This problem if gas hydrate prevention especially in the gas flow lines. The most popular way of gas hydrate prevention is gas hydrate inhibitor supply. As usual it is methanol. To optimize methanol flow rate it is offered to diagnose the conditions of hydrate formation in the flow lines. This problem could be solved by developing the automatic system of diagnosis progressing of hydrate conditions appearance in the flow line and the beginning of this process.
Sony well known methods of such system building are shown in this article. According to carried out research we can say that many factors are affected these systems. The correlation between all these factors could not been described analytically. Also there is no enough quantitative information about these factors. So that is why these systems are appropriately built based on fuzzy cognitive map. The cognitive map is made in order to make up for a deficiency in quantitative information and allows to detect the most important (key) factors. These key factors characterize the correlation between the object and environment and relate with them.
Command variables in the developed system are formed based on online measured pressure and temperature conditions in the beginning and in the end of the flow line, ambient temperature and water dew point temperature. Also well flow rate, gas composition and its density are important. The selected key factor is theoretical hydrating temperature. The changing of the coefficient of heat transmission and other factors (abrasive particles and water vapors in gas, ground condition and surface relief, snow cover and its condition and others) affects on hydrating temperature.
To illustrate the main idea the fuzzy cognitive model is offered in the article. This model corrects the coefficient of heat transmission, and it helps to count theoretical hydrate temperature more accurately. As a consequence it increase the accuracy of methanol supply.
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.