An investigation of methods for calculating the volume of methane dissolved in reservoir water

2021 ◽  
pp. 103-111
Author(s):  
O. V. Fominykh ◽  
S. A. Leontiev

Existing gas production technologies limit gas recovery at the level of 85 %. Therefore, it is important to introduce technologies that make it possible to maximize the volume of production and intensify the inflow; for their selection it is important to have a reliable estimate of the residual gas reserves, since with a significant volume of the aquifer of gas fields, the volume of dissolved gas can be up to 10 % of the total reserves of the reservoir, which should be taken into account when designing the application of technologies to increase gas recovery.The main hydrocarbon dissolving in reservoir water is methane. In this regard, it is of interest to study methods that make it possible to determine the volume of hydrocarbon gases dissolved in saline water, which will make it possible to determine the total reserves of such gas. We investigated the existing methods for calculating the amount of methane dissolved in reservoir water, and gave a quantitative assessment of the volume of gas dissolved in water.

Author(s):  
R. M. Kondrat ◽  
L. I. Khaidarova

The application of non-hydrocarbon gases with the aim of displacing residual gas from depleted fields is substantiated. Mathematical modeling is carried out of the process of residual gas displacing with nitrogen in the GEM compositional simulating module under the conditions of a hypothetical gas reservoir of circular shape. The said module is a part of the licensed CMG computer program. The effect of the cyclical nature of the aquifer injection nitrogen into depleted gas reservoir at different rates till the final gas recovery coefficient for residual gas is developed. The study concerns different durations of nitrogen injection cycles into the reservoir (6, 12, 18, 24, 30, and 36 months) and various correlations of the rates of nitrogen injection and gas production in reservoir conditions of 1:1; 1.5:1; 2:1. During the nitrogen injection into the reservoir, the output wells stopped; whereas after surcease of the nitrogen injection, they were again exploited until the reservoir pressure reached to 0.1 Pprimary. Then the process of cyclic nitrogen injection into the layer continued, until nitrogen break through into the producing wells and its content in the produced products reached 5% vol. The research results were processed in the form of graphical dependencies of reservoir pressure, gas flow rate and gas recovery coefficient for residual gas at the end of the cycle of nitrogen injection into the reservoir as a function of the number of such cycles. The research results indicate a significant effect on the gas recovery coefficient for the residual gas of the duration of the cycle of nitrogen injection into the reservoir and the ratio of rates of nitrogen injection and gas production, with an increase in which the coefficient of gas output gradually decreases. According to the research results, the optimal parameters of the process of nitrogen injection into the reservoir should be chosen on the basis of technological results, as well as technical and economic calculations.


2011 ◽  
Vol 51 (2) ◽  
pp. 684
Author(s):  
Peter Cook ◽  
Yildiray Cinar ◽  
Guy Allinson ◽  
Charles Jenkins ◽  
Sandeep Sharma ◽  
...  

Successful completion of the first stage of the CO2CRC Otway Project demonstrated safe and effective CO2 storage in the Naylor depleted gas field and confirmed our ability to model and monitor subsurface behaviour of CO2. It also provided information of potential relevance to CO2 enhanced gas recovery (EGR) and to opportunities for CO2 storage in depleted gas fields. Given the high CO2 concentration of many gas fields in the region, it is important to consider opportunities for integrating gas production, CO2 storage in depleted gas fields, and CO2-EGR optimisation within a production schedule. The use of CO2-EGR may provide benefits through the recovery of additional gas resources and a financial offset to the cost of geological storage of CO2 from gas processing or other anthropogenic sources, given a future price on carbon. Globally, proven conventional gas reserves are 185 trillion m3 (BP Statistical Review, 2009). Using these figures and Otway results, a replacement efficiency of 60 % (% of pore space available for CO2 storage following gas production) indicates a global potential storage capacity—in already depleted plus reserves—of approximately 750 Gigatonnes of CO2. While much of this may not be accessible for technical or economic reasons, it is equivalent to more than 60 years of total global stationary emissions. This suggests that not only gas—as a lower carbon fuel—but also depleted gas fields, have a major role to play in decreasing CO2 emissions worldwide.


2011 ◽  
Vol 134 (1) ◽  
Author(s):  
John Yilin Wang

Liquid loading has been a problem in natural gas wells for several decades. With gas fields becoming mature and gas production rates dropping below the critical rate, deliquification becomes more and more critical for continuous productivity and profitability of gas wells. Current methods for solving liquid loading in the wellbore include plunger lift, velocity string, surfactant, foam, well cycling, pumps, compression, swabbing, and gas lift. All these methods are to optimize the lifting of liquid up to surface, which increases the operating cost, onshore, and offshore. However, the near-wellbore liquid loading is critical but not well understood. Through numerical reservoir simulation studies, effect of liquid loading on gas productivity and recovery has been quantified in two aspects: backup pressure and near-wellbore liquid blocking by considering variable reservoir permeability, reservoir pressure, formation thickness, liquid production rate, and geology. Based on the new knowledge, we have developed well completion methods for effective deliquifications. These lead to better field operations and increased ultimate gas recovery.


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.


Author(s):  
R. M. Kondrat ◽  
O. R. Kondrat ◽  
L. I. Khaidarova

The relevance and feasibility of extracting residual gas from depleted gas deposits is shown. The possible directions of the extraction of residual gas from depleted gas deposits by its displacement from a porous medium of non-hydrocarbon gases are characterized. The use of nitrogen to displace natural gas from a porous medium has been substantiated. Using the GEM compositional modeling module, which is included in the licensed computer program CMG (Computer Modeling Group), studies were made of the effect of the pressure of the start of injection of nitrogen into the reservoir and the duration of its injection period on the gas recovery coefficient for residual gau. The study was conducted for deposits of square and round shape. The research results are presented in the form of graphical dependencies of the current reservoir pressure, nitrogen content in borehole products and gas recovery coefficient for residual gas from the pressure of the start of injection of nitrogen into the reservoir and the duration of the period of its injection. Using the results of the research, the optimal values ​​of the parameters of the process of injecting nitrogen into the exhausted gas deposits of square and round forms and the corresponding values ​​of the gas recovery coefficient were established. For the considered deposits of square and rounded forms, they are 0.29 Рin and 14.8 months, 0.31 Рin and 12.9 months, respectively. At the time of reaching the volumetric nitrogen content in the producing gas of 5 %, the gas recovery coefficient for residual gas for a square-shaped deposit is 83.91 %, for a round-shaped deposit – 77.49 %. The physical nature of the process of displacing residual gas with nitrogen from depleted gas deposits of square and round forms is characterized.


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):  
R. M. Kondrat ◽  
L. I. Khaidarova

The use of nitrogen for the replacement of residual gas from depleted gas deposits is justified. The latest research and publications on the use of nitrogen to improve gas recovery from depleted gas deposits is analyzed. Using the licensed computer program CMG, the impact of the rate of nitrogen injection into the depleted gas reservoir on its indices for development (reservoir pressure, gas production, nitrogen content in the production gas, and gas recovery factor for the residual gas) has been studied.


Author(s):  
R. М. Kondrat ◽  
L. I. Khaidarova

The research results on residual natural gas displacement from depleted gas deposits by various non-hydrocarbon gases are analyzed. The use of nitrogen for this purpose is proved. The research results and industrial experience in obtaining nitrogen from air and purifying nitrogen from the products of gas production wells in case of nitrogen injection into depleted gas deposits to increase gas recovery are summarized.


Energies ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3829
Author(s):  
Jie Zhang ◽  
Feifei Fang ◽  
Wei Lin ◽  
Shusheng Gao ◽  
Yalong Li ◽  
...  

With the increasing energy demands of current modern society, underground gas storage (UGS) in gas fields is the most popular type of UGS used to meet the seasonal variation of gas consumption. However, compared with gas fields, UGS in gas fields has the characteristics of periodic high-speed injection and production of exploitation modes and operation rules, which causes the rules of gas-water seepage and utilization of reserves to be more particular and complicated. In this paper, based on Wen 23 gas storage, the rules of multicycle injection and production flow and the utilization of UGS pore volume were investigated. The experimental results showed that variation in porosity and permeability caused by injection and production pressure changes in Wen 23 gas storage can be neglected. The pore volume of gas storage and the degree of gas recovery increased gradually in the pre-UGS gas zone, which was higher than that of reservoirs. In the initial stage of UGS operation, the pore volume of gas storage and the degree of gas recovery were low in the gas-drive-water gas zone as a result of water invasion during the process of reservoir exploitation. During operation of multicycle high-speed injection and production, the seepage conditions in the gas-drive-water gas zone gradually improved. The higher the reservoir permeability, the greater increases in pore volume and degree of gas recovery. In the gas-water transition zone, gas and water were reciprocated and displaced with the multicycle injection-production of UGS, resulting in the gradual deterioration of pore volume and gas recovery, which remained stable at a low value. The negative effects of reservoir heterogeneity on the effective utilization of UGS occurred in the gas-water transition zone. These findings may contribute to a better understanding of the rules of multicycle injection and production flow and utilization of UGS to optimize the injection-production efficiency of Wen 23 gas storage.


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