scholarly journals Sensitivity analysis and economic optimization studies of inverted five-spot gas cycling in gas condensate reservoir

Open Physics ◽  
2017 ◽  
Vol 15 (1) ◽  
pp. 525-535 ◽  
Author(s):  
Bilal Shams ◽  
Jun Yao ◽  
Kai Zhang ◽  
Lei Zhang
Keyword(s):  
Sensitivity Analysis ◽  
Gas Injection ◽  
Gas Condensate ◽  
Dew Point ◽  
Injection Timing ◽  
Complex Flow ◽  
Gas Condensate Reservoirs ◽  
Injection Duration ◽  
Well Pattern ◽  
Gas Cycling

AbstractGas condensate reservoirs usually exhibit complex flow behaviors because of propagation response of pressure drop from the wellbore into the reservoir. When reservoir pressure drops below the dew point in two phase flow of gas and condensate, the accumulation of large condensate amount occurs in the gas condensate reservoirs. Usually, the saturation of condensate accumulation in volumetric gas condensate reservoirs is lower than the critical condensate saturation that causes trapping of large amount of condensate in reservoir pores. Trapped condensate often is lost due to condensate accumulation-condensate blockage courtesy of high molecular weight, heavy condensate residue. Recovering lost condensate most economically and optimally has always been a challenging goal. Thus, gas cycling is applied to alleviate such a drastic loss in resources.In gas injection, the flooding pattern, injection timing and injection duration are key parameters to study an efficient EOR scenario in order to recover lost condensate. This work contains sensitivity analysis on different parameters to generate an accurate investigation about the effects on performance of different injection scenarios in homogeneous gas condensate system. In this paper, starting time of gas cycling and injection period are the parameters used to influence condensate recovery of a five-spot well pattern which has an injection pressure constraint of 3000 psi and production wells are constraint at 500 psi min. BHP. Starting injection times of 1 month, 4 months and 9 months after natural depletion areapplied in the first study. The second study is conducted by varying injection duration. Three durations are selected: 100 days, 400 days and 900 days.In miscible gas injection, miscibility and vaporization of condensate by injected gas is more efficient mechanism for condensate recovery. From this study, it is proven that the application of gas cycling on five-spot well pattern greatly enhances condensate recovery preventing financial, economic and resource loss that previously occurred.

Equilibrium Revaporization of Retrograde Condensate By Dry Gas Injection

1968 ◽  
Vol 8 (01) ◽  
pp. 87-94 ◽  
Author(s):  
Lowell R. Smith ◽  
Lyman Yarborough
Keyword(s):  
Gas Flow ◽  
Water Saturation ◽  
Gas Injection ◽  
Gas Condensate ◽  
Dew Point ◽  
Reservoir Pressure ◽  
Sweep Efficiency ◽  
Flowing Fluid ◽  
Condensate Reservoir ◽  
Gas Cycling

Abstract This paper presents results of a laboratory study of retrograde condensate recovery by revaporization into dry injection gas. Flow tests were performed in 10.6-ft long sandpacks at 100F and 1,500 psi. In three runs methane revaporized the liquid from a n-heptane-methane mixture in the presence of immobile water. Two of these tests were water-wet, and the third was totally oil-wet. In the three runs n-heptane recovery was complete after 2.5 hydrocarbon PV of injection. There was no significant performance difference between the two wettability extremes. In a fourth experiment, a methane-hydrogen sulfide mixture revaporized a synthetic light, sour condensate. No water saturation was present. Equilibrium compositions and volumetric data were obtained for the four-component condensate. The heavy component, n-heptane, was removed alter 6 PV production. Comparison of the effluent fluid compositions with known equilibrium data shows that the flowing fluid was equilibrium vapor and that the mixing zone between equilibrium vapor and dry injection gas was short. Data indicated that complete recovery of retrograde liquid occurred after it was contacted by a sufficient quantity of dry gas. Introduction When pressure declines below the fluid dew point in a gas condensate reservoir, a liquid phase forms. In this process, referred to as retrograde condensation, the quantity of liquid formed is frequently small enough that the liquid is not a flowing phase. To prevent loss of valuable retrograde liquids, the process of dry gas cycling has been employed for several years as a more or less standard practice. In this procedure the reservoir pressure is maintained above the fluid dew point so that the liquid components may be produced as vapor and then separated at the surface. Although full pressure maintenance by gas cycling seems ideal in terms of preventing liquids loss, several factors can reduce the attractiveness of such an operation. From a study of a condensate reservoir in Alberta, Canada, Havlena et al. concluded that cycling under conditions of declining pressure leads to economic advantages and to a high recovery of hydrocarbon liquids. This study considered effects of volumetric sweep efficiency, retrograde behavior of the original wet gas and revaporization characteristics of the retrograde liquid when contacted by dry gas. The first major work concerning revaporization of liquid in a gas condensate system is that of Standing et al. Calculations based upon the PVT behavior of a recombined gas condensate fluid indicated that all retrograde liquid can be recovered if it is contacted by a sufficient quantity of dry gas. The paper considered the effect of variable permeability upon the recovery of retrograde liquid. Standing et al. concluded that recovery of heavier components in the retrograde liquid is greatest if reservoir pressure is allowed to decline below the dew point prior to dry gas injection. Since the work of Standing et al., several laboratory studies have been reported which show that recovery of hydrocarbon liquids by vaporization into dry injected gas can contribute to increased recovery above that obtained by ordinary production practices. Vaporization from retrograde condensate, conventional oil and volatile oils reservoirs has been considered. There is little work that deals with revaporization recovery from condensate reservoirs. SPEJ P. 87ˆ

Enhancing Hydrocarbon Production Through Thermal Gas Injection from a Retrograde as Condensate Reservoir in the Western Desert in Egypt

2021 ◽  
Author(s):  
Maged Alaa Taha ◽  
Eissa Shokier ◽  
Attia Attia ◽  
Aamer Yahia ◽  
Khaled Mansour
Keyword(s):  
Carbon Dioxide ◽  
Natural Gas ◽  
Gas Injection ◽  
Gas Production ◽  
Gas Condensate ◽  
Dew Point ◽  
Western Desert ◽  
Co2 Injection ◽  
Hydrocarbon Production ◽  
Gas Condensate Reservoirs

Abstract In retrograde gas condensate reservoirs, condensate blockage is a major reservoir damage problem, where liquid is dropped-out of natural gas, below dew-point pressure. Despite that most of this liquid will not produce due to not reaching the critical saturation, natural gas will be blocked by the accumulated liquid and will also not produce. This work investigates the effects of gas injection (such as methane, carbon-dioxide, and nitrogen) and steam at high temperatures on one of the Egyptian retrograde gas condensate reservoirs. Several gas injection scenarios that comprise different combination of gas injection temperature, enthalpy, injection gas types (CO2, N2, and CH4), and injection-rates were carried out. The results indicated that all conventional and thermal gas injection scenarios do not increase the cumulative gas production more than the depletion case. The non-thermal gas injection scenarios increased the cumulative condensate production by 8.6%. However, thermal CO2 injection increased the condensate production cumulative by 28.9%. It was observed that thermal gas injection does not vaporize condensate It was observed that thermal gas injection does not vaporize condensate more than conventional injection that have the same reservoir pressure trend. However, thermal injection mainly improves the condensate mobility. Appropriately, thermal injection in retrograde reservoirs, is mostly applicable for depleted reservoirs when the largest amount of non-producible liquid is already dropped out. Finally, this research studied executing thermal gas injection in retrograde gas condensate reservoirs, operationally, by considering the following items: carbon dioxide recovery unit, compressors, storage-tanks, anti-corrosion pipe-lines and tubing-strings, and corrosion-inhibitors along with downhole gas heaters.

Case Study of Condensate Dropout Effect in Unconventional Gas/Condensate Reservoirs with Hydraulically Fractured Wells

2022 ◽  
Author(s):  
Ali H. Alsultan ◽  
Josef R. Shaoul ◽  
Jason Park ◽  
Pacelli L. J. Zitha
Keyword(s):  
Gas Production ◽  
Gas Condensate ◽  
Dew Point ◽  
Productivity Index ◽  
Large Reservoir ◽  
Unconventional Gas ◽  
Gas Condensate Reservoirs ◽  
Liquid Saturation ◽  
Reservoir Volume ◽  
Fracture Performance

Abstract Condensate banking is a major issue in the production operations of gas condensate reservoirs. Increase in liquid saturation in the near-wellbore zone due to pressure decline below dew point, decreases well deliverability and the produced condensate-gas ratio (CGR). This paper investigates the effects of condensate banking on the deliverability of hydraulically fractured wells producing from ultralow permeability (0.001 to 0.1 mD) gas condensate reservoirs. Cases where condensate dropout occurs over a large volume of the reservoir, not only near the fracture face, were examined by a detailed numerical reservoir simulation. A commercial compositional simulator with local grid refinement (LGR) around the fracture was used to quantify condensate dropout as a result of reservoir pressure decline and its impact on well productivity index (PI). The effects of gas production rate and reservoir permeability were investigated. Numerical simulation results showed a significant change in fluid compositions and relative permeability to gas over a large reservoir volume due to pressure decline during reservoir depletion. Results further illustrated the complications in understanding the PI evolution of hydraulically fractured wells in "unconventional" gas condensate reservoirs and illustrate how to correctly evaluate fracture performance in such a situation. The findings of our study and novel approach help to more accurately predict post-fracture performance. They provide a better understanding of the hydrocarbon phase change not only near the wellbore and fracture, but also deep in the reservoir, which is critical in unconventional gas condensate reservoirs. The optimization of both fracture spacing in horizontal wells and well spacing for vertical well developments can be achieved by improving the ability of production engineers to generate more realistic predictions of gas and condensate production over time.

scholarly journals Parametric investigation of a large two-stroke marine high-pressure direct injection engine by using computational fluid dynamics method

2020 ◽  
Vol 234 (3) ◽  
pp. 699-711
Author(s):  
Renyou Yang ◽  
Gerasimos Theotokatos ◽  
Dracos Vassalos
Keyword(s):  
Direct Injection ◽  
Gas Injection ◽  
Injection System ◽  
Injection Timing ◽  
Ansys Fluent ◽  
Engine Operation ◽  
Lateral Angle ◽  
Parametric Investigation ◽  
Injection Duration ◽  
Engine Power

This study aims at the parametric investigation of the gas injection system settings of a large marine two-stroke dual fuel engine by using a developed and customized CFD method in the ANSYS Fluent software. The investigated engine injection system parameters include the gas injection timing, the gas injection duration, the gas injector lateral angle, and the gas injector holes number. Based on the comparison of the predicted performance parameters for the closed-cycle processes, the results indicate that the gas injector lateral angle is the most significant parameter that affects the engine power as well as the NO and CO2 emissions. For satisfying the contradictory objectives of retaining the engine power and reducing the NO and CO2 emissions, appropriate design settings for the gas injection are recommended for the investigated engine operation in the gas mode at 75% load.

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