Field Case: Cyclic Gas Recovery for Light Oil-Using Carbon Dioxide/Nitrogen/Natural Gas

Author(s):  
Bernard J. Miller ◽  
Terence Hamilton-Smith
2021 ◽  
Vol 1 (3(57)) ◽  
pp. 6-11
Author(s):  
Serhii Matkivskyi

The object of research is gas condensate reservoirs, which is being developed under the conditions of the manifestation of the water drive of development and the negative effect of formation water on the process of natural gas production. The results of the performed theoretical and experimental studies show that a promising direction for increasing hydrocarbon recovery from fields at the final stage of development is the displacement of natural gas to producing wells by injection non-hydrocarbon gases into productive reservoirs. The final gas recovery factor according to the results of laboratory studies in the case of injection of non-hydrocarbon gases into productive reservoirs depends on the type of displacing agent and the level heterogeneity of reservoir. With the purpose update the existing technologies for the development of fields in conditions of the showing of water drive, the technology of injection carbon dioxide into productive reservoirs at the boundary of the gas-water contact was studied using a digital three-dimensional model of a gas condensate deposit. The study was carried out for various values of the rate of natural gas production. The production well rate for calculations is taken at the level of 30, 40, 50, 60, 70, 80 thousand m3/day. Based on the data obtained, it has been established that an increase in the rate of natural gas production has a positive effect on the development of a productive reservoir and leads to an increase in the gas recovery factor. Based on the results of statistical processing of the calculated data, the optimal value of the rate of natural gas production was determined when carbon dioxide is injected into the productive reservoir at the boundary of the gas-water contact is 55.93 thousand m3/day. The final gas recovery factor for the optimal natural gas production rate is 64.99 %. The results of the studies carried out indicate the technological efficiency of injecting carbon dioxide into productive reservoirs at the boundary of the gas-water contact in order to slow down the movement of formation water into productive reservoirs and increase the final gas recovery factor.


2021 ◽  
Author(s):  
Nazarii Hedzyk ◽  
Oleksandr Kondrat

Abstract Natural gas fields that are being developed in Ukraine, mainly relate to the high and medium permeability reservoirs, most of which are at the final stage of field life. In this situation one of the main sources of additional gas production is unconventional fields. This paper presents the analysis of challenges concerning development of low-permeable reservoirs and experimental results of conducted research, which provide the opportunity to establish technologies for enhance gas recovery factor. For this purpose, a series of laboratory experiments were carried out on the sand packed models of gas field with different permeability (from 9.7 to 93 mD) using natural gas. The pressure in the experiments varied from 1 to 10 MPa, temperature – 22-60 °C. According to the features of low-permeable gas fields development the research of displacement desorption with carbon dioxide and inert gas stripping by nitrogen was conducted. These studies also revealed the influence of pressure, temperature, reservoir permeability and non-hydrocarbon gases injection rate on the course of adsorption-desorption processes and their impact on the gas recovery factor. According to the experimental results of relative adsorption capacity determination it can be concluded that the carbon dioxide usage as the displacement agent can lead to producing adsorbed gas by more than 30% than by using nitrogen. To remove the adsorbed gas just reservoir pressure lowering is not enough due to the nature of adsorption isotherms. Particularly at pressure decreasing by 8-10 times compared to initial reservoir pressure only about 30-40% of the total amount of initially adsorbed gas is desorbed. And at considerable reservoir pressure reduction the further deposit development is not economically profitable. According to the results it was found that in the case of nitrogen usage the most effective method is full voidage replacement at injection pressure of 0.8 of the initial reservoir pressure, and in case of carbon dioxide usage - full voidage replacement method at pressure of 0.6 of the initial reservoir pressure. Taking into account availability of N2 and CO2, N2injection is recommended for further implementation. The influence of displacement agent injection pressure on gas recovery was experimentally proved. The physical sense of the processes taking place during natural gas desorption stimulation by non-hydrocarbon gases was justified. The effect of temperature, pressure and reservoir permeability on methane adsorption capacity were determined. The mathematical model for estimating adsorbed gas amount depending on the reservoir parameters was developed. Obtained results were summarized and recommendations for practical implementation of elaborated technological solutions were suggested.


Author(s):  
Fatema Khatun ◽  
Md. Minhaj Uddin Monir ◽  
S.M. Nafefun Arham ◽  
Zularisam Ab Wahid

Natural gas plays an important role for the economic development of Bangladesh. It is the primary options to satisfy the environmentally clean energy, whereas coal is a dirty energy source and oil creates an unhealthy environment. Bangladesh is the seventh-largest producer of natural gas in Asia. Gas supplies meet 56% of domestic energy demand. The proven natural gas reserve in Bangladesh is only 19.73 Tcf. The Rashidpur Gas Field (RGF) is located in the Sylhet Basin, Northeast Bangladesh. It is 35 km long and 7 km anticlinal structure and asymmetric in nature with steeper eastern flank (22˚ to 25˚) and gentler western flank (8˚ to 12˚). There are two gas zones in depth between 1380m to 2787m below surface. Sandstone reservoirs of Miocene-Pliocene age and are considered to have been originated shallow marine depositional environment. The reservoir porosity-permeability values are very good, with estimated gas initially in place (GIIP) of the RGF was 2.242 Tcf with 58% recovery, thus recording an initial gas reserve is 1.309 Tcf. Five gas producing wells (RP-1, 3, 4, 6 and 7) in the RGF are producing 50 MMscf gas per day. Due to the demand of natural gas with decreasing production rate, this enhanced natural gas plays a vital role in the national economy of the country. This research depicts the development of the daily production of the RGF from 50 MMscfd to 99 MMscfd using software from the existing production wells. Thus the natural gas in the RGF would be enhanced/recovered using carbon dioxide (CO2) gas injection by Enhanced Gas Recovery (EGR) method from the RGF reservoir. Applying this method would play a vital role to increase the daily production rate of the RGF.


Author(s):  
О. R. Kondrat ◽  
S. V. Matkivskyi ◽  
О. V. Burachok ◽  
L. І. Haidarova

The process of carbon dioxide injection into the initial gas-water contact with different rates of its injection, using a 3D model of a gas condensate reservoir, has been investigated. Calculations were carried out for one well injection rate of non-hydrocarbon gas: 40, 50, 60, 70, 80, 90 th.m3/day. According to the calculated results, it has been found that with an increased rate of the carbon dioxide injection into a productive reservoir, the operation duration of production wells decreases until the moment of the carbon dioxide breakthrough. Based on the techno-logical indicators’ analysis of the gas condensate reservoir’s development, it has been found that the introduction of the carbon dioxide injecting technology leads to a reduction in the production of formation water. Due to the injec-tion of non-hydrocarbon gases, a hydrodynamic barrier is created on the initial gas-water contact boundary, which decreases the water influx. Also, the introduction of carbon dioxide injection technology will additionally create an artificial barrier between water and natural gas, which blocks the selective water encroaching and thereby ensure stable waterless operation of production wells. Based on the conducted calculations, the main dependencies have been derived and the corresponding patterns between them have been established. According to the results of the statistical processing of the calculated data, the optimal carbon dioxide injection rate has been determined. At the time of the carbon dioxide breakthrough into the producing well, its optimal well injection rate is 58.17 th.m3/day. The ultimate gas recovery factor for the optimal carbon dioxide injection rate is 63.29 %. Under the same condi-tions during depletion, the ultimate natural gas recovery factor is 53.98%. The results of the carried out studies indicate the technological efficiency of carbon dioxide injection into the initial gas-water contact in order to slow down the formation water encroaching into productive reservoir.


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