Pressure decline below the dew point pressure causes condensation to occur which creates a hydrocarbon liquid saturation in the reservoir. The need for integration had been recognized earlier particularly for gas condensate reservoir, gas cycling processes, and volatile oil systems. The results assume no aquifer influx and ignore the effect of rock and water compressibility. In a typical gas reservoir, gas is stored in the pores by compression. The four layered variable thickness gas condensate reservoir has the grid and scal data scaledup from spe3 gas cycling of retrograde condensate reservoir available pvt data rich in. 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 gas processing plants. Condensate blockage study in gas condensate reservoir. 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. Reservoir that yield natural gas can be classified into essential four categories, these are. Under natural conditions, a gas condensate is a solution of heavier hydrocarbons. Pore throat controlling liquid yield in shale mismatch. In a gas condensate reservoir, the initial reservoir condition is in the singlephase area to the right of the critical point. Stanley kleinsteiber is a senior petroleum engineer with mha petroleum consultants inc. Figure 1 provides a fairly typical gor versus total flow rate response from a gas condensate reservoir.
Condensate dropout occurs in the reservoir as the pressure. 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 the natural gas condensate is also called condensate. 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. Assume that the gas and condensate analyses given in figures 5. It might happen in a lean gas condensate reservoir. Initial oil in place calculation for solution gas drive reservoir duration. Kleinsteiber has over 24 years of petroleum engineering experience and has authored or coauthored papers dealing with production decline type curve analysis, co2 flooding, and depletion of a rich gas condensate reservoir by. Introduction a recombined sample of reservoir fluid is placed in a pressure, volume, temperature i. Optimization of gascondensate reservoir eor technology under.
Gas condensate reservoirs are the categories of hydrocarbon reservoirs. When the pbhf is above dew point, the mw of the surface liquid is the highest. The condensate is not only generated into the reservoir, it is also formed when liquid drops out, or condenses, from a gas stream in pipelines or surface facilities. Its presence as a liquid phase depends on temperature and pressure conditions in the reservoir allowing condensation of liquid from vapor. In gas condensate reservoirs, condensate banking is one of the most. Condensate and gas recovery from a gas condensate reservoir produced by depletion 2. Following success at the main objective, the well was deepened to a final depth of 3633 m. Killing fluid loss mechanism and productivity recovery in a gas. Other factors such as richness of the gas size of he reserve capaeitics of wells nature of the reservoir and mode of occurrence of the gas condensate must e. Prediction of liquid hydrocarbon recovery from a gas. Gas production from gas condensate reservoirs using. Gas reservoirs lend themselves to easy calculation of the hydrocarboninplace through a general gas law equation. Production with gor 100,000 scfbbl is commonly called lean or dry gas.
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. In gas condensate reservoirs, the reservoir temperature lies between the critical temperature and the cricondentherm. Understanding the behaviors of gas condensate reservoirs. Improving gas condensate reservoir productivity aiche. In fact, condensate gas reservoirs produce both condensate gas and. Africa subsahara total reported a naturalgascondensate discovery on block 11b12b in the outeniqua basin, 175 km offshore southern south africa. Members of the transport and energy processes division of aiche are entitled to this content for free. Condensate blockage might play an important role in reduction of the well deliverability of a gas condensate reservoir. New chemical treatment for permanent removal of condensate. Presently, gascondensate reservoirs experience reductions in productivity by as much as a factor of 10 due to the dropout of liquid close to the wellbore.
Producing the gas to separator conditions creates a mixture of gas and condensed oil. Gas condensate reservoir petroleum reservoir gases. Successful field implementation of a novel solidsfree system to control fluid loss during overbalanced workover. Gulf professional publishing boston london auckland johannesbourg melbourne new delhi second edition reservoir eng fob 20011029 16. Flow behavior of gascondensate wells stanford university. Gas reservoir management training course petroskills grm. Simulation study of enhanced condensate recovery in a gas. In a cbmshale reservoir, in addition to the free gas g f stored in the fracture network, gas is stored within the coal shale matrix by adsorption. 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. Gas zfactor muz standing would be happy to hear that the zfactor is still the only pvt property which always needs accurate determination in a gas condensate reservoir as in a dry gas reservoir. Condensate reservoirs are inherently more difficult to characterize correctly. The feasibility of different methods such as periodic hot gas injection and gas reinjection using horizontal wells were assessed using different reservoir fluid and injection conditions. Introduction gas condensate reservoirs mostly produce gas, with some liquid dropout, frequently occurring in the wellhead separators.
Gas injection techniques for condensate recovery and. Ron terry discusses gas condensate reservoirs, calculating hydrocarbon in place using two methods. Pdf understanding the behaviors of gas condensate reservoirs. The calculations use results from cce and cvd experiments. The gas is much more mobile than the condensate and, therefore, the gascondensate ratios gcr exhibited at surface are commonly higher than that of the reservoir fluid. Calculation of hydrocarboninplace volume of a gascondensate reservoir from the geologic, reservoir, and production data requires a clear understanding of the behavior of oil and gas under various reservoir and surface operating conditions. It is intended both for students who are new to the subject and practitioners, who may use this book as a reference and refresher. Naturalgas condensate is a lowdensity mixture of hydrocarbon liquids that are present as gaseous components in the raw natural gas produced from many natural gas fields. A commercial simulator was then used to carry out numerical reservoir simulation of fluid flow in the north field. Petroleum reservoirs are broadly classified as conventional and unconventional reservoirs. A petroleum reservoir or oil and gas reservoir is a subsurface pool of hydrocarbons contained in porous or fractured rock formations. Developing an easytouse simulator to thermodynamic.
In this chapter, gas reservoirs have been divided into three groups. Pdf understanding gascondensate reservoirs navneet. In a retrograde gas condensate reservoir middle, temperature is below the cricon dentherm, causing oil to condense as pres sure decreases. The depletion of gas condensate reservoirs to pressures below the dew point has been studied by reservoir engineers for many years. K4 gas condensate, andviscosity were calculated by compositions of separatorgas liquid the model. Rich gas condensaterichrich gas condensate gas condensate 0 0. One question often asked is during and after sampling.
The vapourvapour interface observation and appraisement of a. Summary development of gascondensate reservoirs is a complicated problem by itself. Spinfree cc2 implementation of induced transitions between. The composition and properties of the recombined analysis are used for reservoir calculations. Chapter 5, part 1 of the online course in applied petroleum reservoir engineering. The mbo model representation of compositional phenomena for a gas condensate reservoir proved to be successful in the following cases. Jasmine, a gascondensate reservoir, is located 240km south east of the coast of aberdeen and is expected to start production at the end of 2012. Free gas recovery factor prediction for horizontal well as a function of. Understanding of phase and fluid flow behavior relationships is essential if we want to make accurate engineering computations for gascondensate systems e.
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. 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. A gas condensate with low condensate formation in the reservoir when the bottomhole pressure is reduced below the dewpoint pressure. Gascondensate reservoirs differ from drygas reservoirs. The objective of this book is to bring together the fundamentals of gas reservoir engineering in a coherent and systematic manner. In conventional reservoirs, the naturally occurring hydrocarbons, such as crude oil or natural gas, are trapped by overlying rock formations with lower permeability, while. Gas condensate reservoirs are distinguished by producing both gas and condensate liquid at the. Once an accurate model was obtained, the following three solutions to. It is shown that both the temperature and composition of the injection fluids play a key role in the remediation of productivity and condensate recovery. Pdf gas condensate reservoir engineering researchgate. The production of condensate reservoirs can be complicated. Gas condensate reservoir free download as pdf file.
The compositional case optionally uses tabular kvalues versus p. The gas will drop out liquid by retrograde condensation in the reservoir, when the pressure falls below the dew point. The accumulation of liquid condensates around the production well can. The gascondensate content in gases of various deposits ranges from 12 to 700 cm3 per 1 m3 of gas. A drygas reservoir is defined as producing a single composition of gas that is constant in the reservoir, wellbore, and leaseseparation equipment throughout the life of a field. Shift factors3 are included to account for volume translation. The development of gascondensate reservoirs by gas injection is treated in chapter 12. Simulation study of enhanced condensate recovery in a gascondensate reservoir iranian journal of chemical engineering, vol. Early developments in reservoir engineering analysis relied on zerodimensional or tank material balances for the evaluation and forecasting of reservoir performance. The phase diagram e shows the r trograde gas must have a temperature higher than the critical temperature.
Pore throat controlling liquid yield in shale mismatch between dry produced gas at surface and wet gas or condensate in the reservoir jeanyves d. Appendix b includes some special physical and mathematical constants that are of particular interest in gas reservoir engineering. Gascondensate reservoirs exhibit complex phase and flow behaviors due to the appearance of condensate banking in the near well region. Pdf well productivity estimation in gas condensate reservoirs is still a. This synthetic reservoir model of a single layer homogenous reservoir was generated. A natural gas liquid with a low vapor pressure compared with natural gasoline and liquefied petroleum gas. A further complication of this problem is that the composition of the surface liquid also changes. A gas well is producing gas with a specific gravity of 0. Gascondensate reservoirs represent a vital source of hydrocarbon reserves which have been recognized as a reservoir type, possessing the most complex flow and thermodynamic behaviors. The operating method for each reservoir should be based upon the character istics of the gas condensate at reservoir conditions.
Gascondensate reservoir article about gascondensate. The brulpadda well encountered 57 m of net gas condensate pay in lower cretaceous reservoirs. Gas reservoirs can be classified into dry gas reservoirs, wet gas reservoirs and gas condensate reservoirs. The first step of the study involved gathering north field reservoir data from previously published papers. Gas flow tests have been used to study the effectiveness of each method to restore or maintain gas production for gas condensate reservoir.
According to the previous studies, the addition of some nitrogen causes a considerable increase in mixture dew. Condensate is mainly composed of propane, butane, pentane and heavier hydrocarbon fractions. Appendix a lists the commonly used units in gas reservoir engineering, along with their conversion factors. Gascondensate reservoirs are distinguished by producing both gas and condensate liquid at the surface. As the reservoir pressure is reduced, gas is desorbed from the surface of the matrix. The literature shows many differences between gas condensate reservoirs and dry gas reservoirsi6. The fluid selected for our study is a very rich gas condensate taken from cusiana field located 125 miles northeast of. Compositional modeling of gascondensate reservoirs. The percentage of vapor decreases, but can increase again with continued. Pdf gas condensate reservoir performance free download as pdf file.
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