Field development. Reservoir engineering. Production
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.
STIMULATION OIL FIELD BY INJECTION OF HYDROCHLORIC ACID UNDER PRESSURE AT OIL AND GAS PRODUCTION DEPARTMENT “TUYMAZANEFT”
Different forms of the hydrochloric acid treatment of wells are the most effective method of increase of oil recovery in the development of productive carbonate reservoirs, the essence of which is to increase the permeability of the bottomhole formation zone. The intensification of inflow of oil with the hydrochloric acid treatment is very widely used In the fields West of the Bashkortostan Republic. In recent years, the technology of the acid treatment has improved.
Summing up the experience of conducting and the effectiveness of the hydrochloric acid treatment of wells of NGDU “Tuymazaneft” for 1971 – 1985 effect per operation averaged 185 ton (verkhnekamsky layers) and 240 ton (in the processing of limestone tournaisian tier). As irrigation wells, the effectiveness of the treatments began to decline and in 1984 amounted to 92 ton and it is noted that the hydrochloric acid processing in the wells with an output of less than 0.5 t/day is not effective. It is determined that carrying out hydrochloric acid treatment under conditions of NGDU “Tuymazaneft” is effective when the water cut to 20 %. At higher water cut production growth oil for one treatment drastically reduced and conducting a hydrochloric acid treatment becomes economically unprofitable.
Analysis of the results of the HAT shows that measures of increasing oil recovery by injection of hydrochloric acid has a beneficial effect on the reservoir at low water content (55%) and low average daily production wells.
Currently, there are a huge number of packers type of tool for conducting geological and technical measures in open hole. But despite the great diversity of types of packers, all united by the presence of common deficiencies, namely:
– not reliable sealing packer;
– the destruction of the sealing element in rubber re-planting packer in the wellbore;
– inadvertent operation of the packer during tripping operations (SPO)
– the probability of sticking packer in the wellbore.
The above disadvantages packers may cause complications in the wells that increases the downtime or loss of the well and consequently leads to high cost oil and gas companies.
To address the identified shortcomings in the packer, packer radically new design for the open hole was developed. Special attention was given to the design of sliding bearings to prevent leaking of the sealing rubber member due to occurrence of the pressure difference, and provide further breakdown reliable packer. Increasing the number of cycles stall rubber sealing element is achieved by adding a rubber composition belting cord, leading to increasing its stiffness, with slightly decreased rubber elasticity. Specially designed landing node allowed to exclude spontaneous land packer during tripping, thereby eliminating the possibility of complications during tripping. As a result of constructive upgrades for openhole packer column significantly decreased the percentage of no packer leakage, as was improved sealing rubber elements and node responsible for the safety of these elements.
Thus, to the ins developed packer designs include the preservation of the performance of the sealing rubber member by applying belting cord in the rubber and the mechanism of sliding bearings, which allows multiple re-planting packer in open hole. Just packer design allows exclusion of unauthorized operation during tripping. Another advantage of the upgraded design is to improve the packer tightness when working in wells with a large pressure drop.