Well productivity is a critical issue in the development of many gas condensate reservoirs. The reservoir rock must be permeable and porous to contain the gas, and it has to be capped by impervious rock in order to form an effective seal that. Gas reservoir, in geology and natural gas production, a naturally occurring storage area, characteristically a folded rock formation such as an anticline, that traps and holds natural gas. According to the complexity of the reservoir fluid phase behavior, reservoir modeling is classified under two distinct groups. In contrast, gas condensate reservoirs will always produce gas mixed with condensate, with the quantity of condensate varying from one reservoir to another. Developing a rapid and inexpensive technique to accurately estimate cgr. Gas condensate is a hydrocarbon liquid stream separated from natural gas and consists of highermolecularweight hydrocarbons that exist in the reservoir as constituents of natural gas but which are recovered as liquids in separators, field facilities, or gasprocessing plants. Gas condensate is a lowdensity mixture of liquid hydrocarbons that are present as gaseous components in the natural gas. Depleted gas condensate reservoirs can be revitalized by gas injection. A production data analysis model for gascondensate reservoirs.
Appendix a lists the commonly used units in gas reservoir engineering, along with their conversion factors. Gas condensate reservoirs are distinguished by producing both gas and condensate liquid at the. The feasibility analysis of underground gas storage during. This is a pdf file of an unedited manuscript that has been accepted for publication. The development of gas condensate reservoirs by gas injection is treated in chapter 12. Constantcomposition expansion tests were performed to determine the phase behavior and volumetric properties of reservoir fluid using an ultrahighpressure fluid pvt test system.
Condensate dropout occurs in the reservoir as the pressure. A new reservoir protection technology for offshore. Appendix b includes some special physical and mathematical constants that are of particular interest in gas reservoir engineering. Calculating well deliverability in gas condensate reservoirs, 10 th european symposium on improved oil recovery.
Flow behavior of gascondensate wells stanford earth. Petroleum reservoirs are broadly classified as conventional and unconventional reservoirs. To optimize the development of the filed, an integrated model was created. The objectives of this comprehensive research entail reservoir core analysis, reservoir fluid study, investigation and optimization of improved condensate recovery during gas storage processes.
Due to the increasing demand for gas consumption during cold seasons, it is a sense of urgency to provide a reliable resource for gas supply during these periods. J petrol explor prod technol wettability alteration to intermediate gas wetting in lowpermeability gas condensate reservoirs shuo zhang 0 1 guancheng jiang 0 1 le wang 0 1 wang qing 0 1 haitao guo 0 1 xinguo tang 0 1 diangang bai 0 1 0 h. Rich gas condensaterichrich gas condensate gas condensate 0 0. Compositional modeling of gascondensate reservoirs. The calculations use results from cce and cvd experiments. Hence, the gas condensate, which is a supercritical fluid, enters the wde at the dew point pressure. This paper presents the analysis of gas condensate field a development optimization with the purpose of maintaining constant gas production at the 20 level for 8 years taking into account mentioned factors. The course is designed for mid to senior level reservoir and production engineers involved in the evaluation, planning and development of gas condensate reservoirs. Ding zhu condensate blockage negatively impacts large natural gas condensate reservoirs all over the world. Modeling and optimization of the rich gascondensate reservoir.
Gascondensate flow modelling for shale gas reservoirs. Gas condensate pvt petroleum reservoir pressure free 30. The study revealed that the dry gas injection into gas condensate reservoirs minimized the dew point pressure by 18. Pdf well productivity estimation in gas condensate reservoirs is still a challenge. The compressibility factor and dewpoint pressure were. Fully compositional integrated subsurfacesurface modeling for critical gas condensate reservoirs. A composition stream from reservoir to the market has been obtained as a result of upstream, midstream and downstream retrograde gascondensate models. Wettability alteration to intermediate gaswetting in low. Phase behavior, dew point pressure and maximum recovery are studied after and before injection. Producing the gas to separator conditions creates a mixture of gas and condensed oil. The study revealed that the dry gas injection into gascondensate reservoirs minimized the dew point pressure by 18. Gas condensate reservoirs usually exhibit complex flow behaviors due to the buildup of condensate banks around the wells when the bottomhole pressure drops below the dew point.
Phase change tracking approach to predict timing of condensate. A petroleum reservoir or oil and gas reservoir is a subsurface pool of hydrocarbons contained in porous or fractured rock formations. This question is especially pertinent to nearcritical or very rich gas. This book is conflated based on the last scientific researches by authors and according to the last books and articles which are published in fundamentals of reservoirs engineering. Presently, gas condensate reservoirs experience reductions in productivity by as much as a factor of 10 due to the dropout of liquid close to the wellbore. Apr 24, 2018 due to the increasing demand for gas consumption during cold seasons, it is a sense of urgency to provide a reliable resource for gas supply during these periods. Pdf understanding the behaviors of gas condensate reservoirs. Effect of dry gases injection into egyptian gascondensate. Condensate and gas recovery from a gas condensate reservoir produced by depletion 2. The selected solvent, isopropyl alcohol, and its mixture with methanol caused the removing of condensate blockage, condensate accumulation delay and increment of gas productivity.
The objectives of this comprehensive research entail reservoir core analysis, reservoir fluid study, investigation and optimization of improved condensate recovery during gas storage processes in one of iraniandepleted fractured gas. Some gas species within the raw natural gas will condense to a liquid state if the temperature is reduced to below the hydrocarbon dew point. This casts new insight into the conventional explanation that the productivity loss in gas condensate reservoirs, when the pressure near the wellbore reaches the dew point, is only due to relative permeability effects. At discovery, these reservoirs are often in single phase. Natural gas condensate aka gas condensate, condensate, natural gas liquids is a lowdensity, highapi gravity liquid hydrocarbon phase that generally occurs in association with natural gas. Operators realise, however, that applying accumulated knowledge about conventional gas oil systems in gas condensate reservoirs without. The cost and risk to develop reservoirs under these extreme conditions highlights the need to be able to confidently predict the recovery of gas and liquids. Partners are qatar petroleum with 25%, canadian natural resources with 20%, and main street, a south african consortium, with 10%. Gas condensate pseudopressure in layered reservoirs. A new multiphase model to analyze gas condensate production data is presented. Production from gas condensate reservoir poses the major challenge of condensate banking or blockage.
Production with gor 100,000 scfbbl is commonly called lean or dry gas. Hydrocarbon liquid dissolved in saturated natural gas that comes out of solution when the pressure drops below the dewpoint. Field work and laboratory determination of cgr is both time consuming and resource intensive. Condensatetogas ratio cgr plays an important role in sales potential assessment of both gas and liquid, design of required surface processing facilities, reservoir characterization, and modeling of gas condensate reservoirs. Most known retrograde gascondensate reservoirs are in the range of 3000 to 8000 psi and 200400. Bai tan hai development company, china national petroleum corporation, tianjin 300289, china 1 s. Gas condensate reservoirs represent a vital source of hydrocarbon reserves which have been recognized as a reservoir type, possessing the most complex flow and thermodynamic behaviors. In contrast, gascondensate reservoirs will always produce gas mixed with condensate, with the quantity of condensate varying from one reservoir to another. Various methods were addressed to remediate the productivity decline, for example, fracturing, gas injection, solvent injection and chemical treatment. According to the previous studies, the addition of some nitrogen causes a considerable increase in mixture dew.
In a retrograde gas condensate reservoir middle, temperature is below the cricon dentherm, causing oil to condense as pres sure decreases. A case study of gascondensate reservoir performance under bottom. During reservoir depletion liquid condense out of the gas. J petrol explor prod technol wettability alteration to intermediate gaswetting in lowpermeability gascondensate reservoirs shuo zhang 0 1 guancheng jiang 0 1 le wang 0 1 wang qing 0 1 haitao guo 0 1 xinguo tang 0 1 diangang bai 0 1 0 h. Calculating well deliverability in gas condensate reservoirs. Gas condensate reservoirs in niger delta and around the world are becoming increasingly important as a result of additional liquid recovery and increasing demand for light oil and natural gas. Optimization of gas condensate field a development on the. The development of gascondensate reservoirs by gas injection is treated in chapter 12.
Understanding of phase and fluid flow behavior relationships is essential if we want to make accurate engineering computations for gascondensate systems e. Gas recovery from gas condensate reservoirs download pdf info publication number us3149668a. Gas injection techniques for condensate recovery and. The reason is 1 to get an accurate and consistent estimate of the initial gas and condensate in place, and 2 to accurately predict the gas and condensate recovery as a function of pressure during depletion drive. Often times, it is safe to assume that reservoir fluid behavior is only a function of pressure and independent of.
The study also investigates the performance of various reservoir fluid thermodynamic conditions, injection design variables, and economic. Following success at the main objective, the well was deepened to a final depth of 3633 m. Gascondensate reservoirs differ from drygas reservoirs. Fundamentals of gas reservoir engineering, volume 23 elsevier. A major question in the use of the blackoil model is whether the twocomponent description can represent ade quately the compositional phenomena active during the depletion or the cycling of gas condensate reservoirs. At the time of discovery, gas condensates are often found as singlephase gas in the reservoir. Four reservoir samples under ultrahighpressure and hightemperature conditions were collected from condensate gas fields in china. To model the condensate banking or water influx effects on gascondensate reservoirs, both cartesian and radial models have been used in the. The key feature of these reservoirs is the condensate banking which reduces significantly the well deliverability when the condensate forms in the reservoir below the dew point pressure. Gas condensate pvt petroleum reservoir pressure free. Prerequisites and linking courses a good general knowledge of reservoir engineering is assumed through your own work, or having attended n933. Natural gas processing reservoir fluids and their phase d duration. Gas reservoirs lend themselves to easy calculation of the hydrocarboninplace through a general gas law equation. Prediction of condensatetogas ratio for retrograde gas.
Simulation study of enhanced condensate recovery in a gascondensate reservoir iranian journal of chemical engineering, vol. Typically, gas condensate contains hydrocarbons boiling up to c 8 fig. The results assume no aquifer influx and ignore the effect of rock and water compressibility. Simulation study of enhanced condensate recovery in a gas condensate reservoir iranian journal of chemical engineering, vol. Condensate blockage study in gas condensate reservoir pdf. Dur ing the production phase of gas condensate reservoir multi phase fluid problem.
Its presence as a liquid phase depends on temperature and pressure conditions in the reservoir allowing condensation of liquid from vapor. To evaluate the effect of reservoir pe rmeability on gas condensate blockage, the reservoir permeability was. Lean gas condensateleanlean gas condensate gas condensate rich gas condensaterichrich gas condensate gas condensate 0 0. The depletion of rich, gas condensate reservoirs to pressures significantly below the dew point is a topic of increasing interest as deeper, hotter hydrocarbon reservoirs are exploited. Increasing well productivity in gas condensate wells in qatars north field. Carbon dioxide is a promising injection fluid in gas condensate reservoirs due to large density and viscosity difference between gas condensate r esident gas and co2 i njection fluid that effectively will help to enhance gas recovery avoiding mixing, a main concern for degradation of value of remaining resident gas. This article is a synopsis of paper spe 59773, investigation of well productivity in gascondensate reservoirs, by a. Gas condensate reservoirs stand as new frontiers as the petroleum industry is currently undergoing unprecedented surge of activities in securing enough hydrocarbon resources to satisfy the market.
Us3149668a gas recovery from gas condensate reservoirs. Gascondensate reservoirs represent an important part of these resources. Oct 01, 2016 gas condensate reservoirs represent an important part of these resources. The brulpadda well encountered 57 m of net gas condensate pay in lower cretaceous reservoirs. Simulation study of enhanced condensate recovery in a gas. Naturalgas condensate, also called natural gas liquids, is a lowdensity mixture of hydrocarbon liquids that are present as gaseous components in the raw natural gas produced from many natural gas fields. Natural gas processing reservoir fluids and their phase d. Some gas species within the raw natural gas will condense to a liquid state if the temperature is reduced to below the hydrocarbon dew point temperature at a set pressure. Pdf gas condensate reservoir engineering researchgate. Depending on objective and availability, different injection gases have been suggested and tested for gas injection enhanced gas recovery egr, most frequently dry hydrocarbon gas, carbon dioxide or carbonated natural gas and nitrogen are considered. In gas condensate reservoirs, by reservoir depletion, pressure decreases below the dew point pressure of the fluid and condensate forms in the reservoir. Phase behavior is relevant to every aspect of petroleum and natural gas engineering. Well productivity in gascondensate reservoirs onepetro.
Gas reservoir management training course petroskills grm. Laboratory modelling on enchanced gas and condensate. Santa barbara and pirital fields, venezuela abstract this paper presents the workflow and learned lessons during the construction of a fully compositional integrated subsurfacesurface model for the santa barbara and pirital fields, which are. Laboratory modelling on enchanced gas and condensate recovery. Calculating well deliverability in gas condensate reservoirs, 10. Analysis of vapour liquid equilibria in unconventional. Pdf on sep 10, 2015, ali vatani and others published gas condensate reservoir engineering find, read and cite all the research you need on researchgate. Us4765407a method of producing gas condensate and other. Abstract ten years of operation of gascondensate reservoirs has verified the necessity for and practicability of cooperative and unitized operation. For example, the gas production of target well b1, studied in this paper plummeted from 50,000 to 0 m3d after the typhoon.
However, calculation of hydrocarboninplace of a gas condensate reservoir is more complex because of the change from a single gaseous phase in the reservoir to two phases gas and condensate at the surface. Data from 17 fields are included in this paper to demonstrate that severe loss of gas recovery occurs primarily in low productivity reservoirs. Sep 27, 20 gas condensate reservoirs part 1 duration. The feasibility analysis of underground gas storage during an. Africa subsahara total reported a naturalgascondensate discovery on block 11b12b in the outeniqua basin, 175 km offshore southern south africa. Fully compositional integrated subsurfacesurface modeling. Experiments and modeling of volumetric properties and. Liquid buildup around the well can cause a significant reduction in productivity, even in lean gas condensate reservoirs where the maximum liquid drop. Apr 22, 2012 condensate to gas ratio cgr plays an important role in sales potential assessment of both gas and liquid, design of required surface processing facilities, reservoir characterization, and modeling of gas condensate reservoirs.
Gascondensate reservoirs exhibit different thermodynamic and flow behavior and the. Us4765407a us06902,247 us90224786a us4765407a us 4765407 a us4765407 a us 4765407a us 90224786 a us90224786 a us 90224786a us 4765407 a us4765407 a us 4765407a authority us. Gas condensate reservoirs differ from dry gas reservoirs. Pdf gas condensate pseudopressure in layered reservoirs. Critical evaluation of empirical gas condensate correlations. Gas condensate reservoirs are the categories of hydrocarbon reservoirs. Method of producing gas condensate and other reservoirs en us06902,247 19860828. Early developments in reservoir engineering analysis relied on zerodimensional or tank material balances for the evaluation and forecasting of reservoir performance. Wells in tight sandstone condensate gas reservoirs of east china sea often suffer from dramatic production declines after being closed for several days. Condensate blockage study in gas condensate reservoir. Among them, gas injection techniques have been used as options to prevent retrograde condensation by vaporizing condensate andor by enhancing condensate recovery in gascondensate reservoirs.