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. 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 a gas condensate reservoir, the initial reservoir condition is in the singlephase area to the right of the critical point. The depletion of gas condensate reservoirs to pressures below the dew point has been studied by reservoir engineers for many years. Most known retrograde gascondensate reservoirs are in the range of 3000 to 8000 psi and 200400. Gascondensate reservoirs represent an important source of hydrocarbon reserves and have long been. Liquid formation in gascondensate reservoirs occurs when the bottomhole flow pressure decreases below the dew point of the reservoir gas kniazeff and nvaille, 1965. The vertical line on the phase diagram shows the phase changes in the reservoir, while the curve line shows these changes as the fluid cools going up the wellbore and into the separator. 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. Crude oil and lease condensate proved reserves rose by 12%,and natural gas proved reserves rose by 9% table 1. If the reservoir pressure falls below the dewpoint pressure when producing a gas condensate reservoir, liquid dropout takes place in the reservoir. The operating method for each reservoir should be based upon the character istics of the gas condensate at reservoir conditions. Evaluation of gas condensate reservoir behavior using. The phase diagram shows the retrograde gas field must have a temperature higher than the critical point temperature.
Simulation of gas condensate reservoir performance onepetro. The main focus of this thesis is to evaluate condensate blockage problems in the north field, qatar, and then to propose solutions to increase well productivity in these gas condensate wells. Gas condensate reservoirs differ from dry gas reservoirs. Utilization of natureinspired algorithms for gas condensate reservoir.
Phase behavior is relevant to every aspect of petroleum and natural gas engineering. On the contrary, the performance of the 2 horizontal wells in a tight gas condensate reservoir is superior to that of the 6. The percentage of the condensate and liquefiable hydrocarbons ultimately recovered from the reservoir, therefore, is equivalent to the percen tage of the gas recovered, usually 80 to 90 per cent. Condensate blockage study in gas condensate reservoir article in journal of natural gas science and engineering 33. Pdf field operational problems due to condensate formation in. The pressure profile around the wellbore in a gas condensate reservoir danesh et al. Condensate reservoirs are inherently more difficult to characterize correctly. 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. Several examples of severe productivity decline are available in the literature.
But in gas condensate reservoirs, the relative permeability of both gas and. Modelling of gascondensate flow around horizontal and. Gas condensate reservoirs are distinguished by producing both gas and condensate liquid at the. Table 1 indicates the characteristics of the reservoir used for this study. Constant volume depletion cvd is an experimental procedure used to study gascondensate samples by being equilibrated in a pvt cell at reservoir temperature and pressure 7. Gas reservoir management training course petroskills grm. Simulation study of enhanced condensate recovery in a gas. Gas condensate reservoirs are primarily gas reservoir but when reservoir pressure declines below dew point pressure the liquid begins produced. The commission of the european communities, having regard to the treaty esta blishing the european community, having regard to the agreement on the european economic area, and in particular article 57 thereof, having regard to council regulation ec no 92004 of 20 january 2004 on the control of concentrations between undertakings1.
The only liquid associated with the gas from a dry gas reservoir is water. In this kind of fluids, two phenomena named negative inertia and positive coupling, become significant in the high velocity zone around the wellbore. Early developments in reservoir engineering analysis relied on zerodimensional or tank material balances for the evaluation and forecasting of reservoir performance. Application of general material balance on gas condensate reservoirs giip estimation. In case of isothermal reduction of the formation pressure, part of them condenses in the form of gas condensate. Reservoir pressure of condensate gas reservoir is an indispensable parameter for calculation of gas reserves, gas well productivity evaluation, dynamic analysis, and evaluation of anticondensate. Abstract ten years of operation of gascondensate reservoirs has verified the necessity for and practicability of cooperative and unitized operation. Specific gravity up volumetric factors bo and bg png 520. Figure 1 provides a fairly typical gor versus total flow rate response from a gas condensate reservoir. Imperial college london department of earth science. In all cases their compositions depend upon their source, history, and present thermodynamic conditions. Agreement between resulting blackoil and fully compositional simulations of gas condensate reservoir depletion is demonstrated for a very rich, nearcritical condensate.
A gas condensate with low condensate formation in the reservoir. Pressure decline below the dew point pressure causes condensation to occur which creates a hydrocarbon liquid saturation in the reservoir. Pdf production data analysis of liquid rich shale gas. Energy information administration eias proposed definitions for natural gas liquids 1 june 14, 20. Effect of dry gases injection into egyptian gascondensate. Once an accurate model was obtained, the following three solutions to. Normal engineering practice is to combine ift and velocity through the socalled capillary. The literature shows many differences between gas condensate reservoirs and dry gas reservoirsi6. The value below which the absolute difference between a pair of succesive test results obtained using the same method, on identical test material, by the same operator, using the same apparatus, in the same laboratory, within a short time interval, may be expected to lie with a specified probability. Reservoir that yield natural gas can be classified into essential four categories, these are. 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. Nodoc estimate and simulate the cost for the remoavl of condensate and water from gas. Ravenscraft why are we in the midst of one of the largest merger waves in united states history. Gas condensate field produce mostly gas, with some liquid dropout, frequently occurring in the separator.
According to the previous studies, the addition of some nitrogen causes a considerable increase in mixture dew. Accumulation of condensate in the reservoir causes a reduction in gas. The first step of the study involved gathering north field reservoir data from previously published papers. Gas condensate reservoirs have more complicated performance. Simulation of gas condensate reservoir performance keith h.
Clearly this is an opportunity for new market development, and the bizdev community is hard at work coming up. Interpretation of the unusual fluid distribution in the. Crude oil and natural gas proved reserves, yearend 2018. Flow behavior of gascondensate wells stanford university. In a gascondensate reservoir, the initial reservoir condition is in the singlephase area to the right of the critical point. In the first region that is farthest from the wellbore, the reservoir fluid. In this research, the effort was put to combine ga. Jamal jamaluddin rosharon, texas jairam kamath chevron energy technology company san ramon, california, usa robert mott independent consultant dorchester, uk gary a. At the same time the production of plant condensate, a. Evaluation of gas condensate reservoir behavior using velocity. Khami is a unique low permeable, deep and high pressure gas condensate reservoir. Gascondensate reservoirs exhibit complex phase and flow. Jasmine, a gas condensate reservoir, is located 240km south east of the coast of aberdeen and is expected to start production at the end of 2012.
The test is performed to determine the dew point pressure 6. A glut of condensates has developed and is getting worse. When a gas enters a gas processing plant, always there is a slug catcher unit which the gas passes. Combine equation 6 with equation 9, then the expression is.
This course will help participants understand the engineering drivers on gas reservoir management and how a gas reservoir s value can be maximized through sound engineering practices. At early stages of reservoir production period, the corresponding fluid in gas condensate reservoirs is a singlephase gas. Gascondensate reservoir article about gascondensate. 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. Liquid builds up in the near wellbore area causing what is known as. Thornton abstract ten years of operation of gas condensate reservoirs has verified the necessity for and practicability of co operative and unitized operation. Afterwards, due to reservoir pressure decline below its dew point pressure, condensate formation occurs which is referred to as condensate blockage. Nov 27, 2014 in the first, lets define the condensate banking blockage. To access the remainder of through the looking glass. Composition variation during flow of gascondensate wells. Agreement between resulting blackoil and fully compositional simulations of gas condensate reservoir depletion is demonstrated for a. One question often asked is during and after sampling. This procedure is applied with material balance requirements in generation of twocomponent, blackoil properties for gas condensates.
Reservoirs with the relative amount of at least 5 to 10 grams of condensate per cubic meter are. The gen eralized form is obtained by manipulation of martins. Gas reservoirs lend themselves to easy calculation of the hydrocarboninplace through a general gas law equation. Pdf application of general material balance on gas. Condensate blockage study in gas condensate reservoir.
Natural gas condensate is a lowboiling mixture of hydrocarbon liquids that are present as gaseous components in the raw natural gas produced from many natural gas fields if the raw gas temperature is reduced to below its hydrocarbon dew point, the liquids begin to condense out of the gas. The waterdrive condensate gas reservoir is ranked among the most complex types during development. The phase diagram of two binary mixture reservoir fluids used in the present study, a c1. Spe, iniercomp resource development ana engineering, inc. The need for integration had been recognized earlier particularly for gas condensate reservoir, gas cycling processes, and volatile oil systems. Stanley kleinsteiber is a senior petroleum engineer with mha petroleum consultants inc. Calculating well deliverability in gas condensate reservoirs. Natural gas 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. Gas condensate reservoir free download as pdf file. Natural gas condensate encyclopedia article citizendium. Slug catcher is used at the terminus of offshore pipelines to catch large slugs of liquid in pipelines, to hold these slugs temporarily, and then to allow them to follow into downstream equipment and.
To enhance the grid definition near the well, especially for the gas condensate reservoir simulation studies and to allow accurate modeling of near wellbore gas condensate behavior, radial local grid refinement is used. 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. It is essential to take account of this condensate blockage effect when calculating well productivity. Condensate dropout occurs in the reservoir as the pressure. Simulation study of enhanced condensate recovery in a gascondensate reservoir iranian journal of chemical engineering, vol. Crude oil and natural gas proved reserves, yearend 2018 another year of stronger oil and natural gas prices increased 2018 oil and natural gas proved reserves in the united states to another alltime record level. Imperial college london department of earth science and. A new method for the dynamic reserves of gas condensate. Gas condensate is one of the most different fluids in reservoir simulation due to retrograde condensation in case of pressure reduction. At exxon, several fields have been identified in which productivity loss below the dew point has significantly reduced gas recovery by pressure depletion. The yh23 gas condensate reservoir is taking as a typical subject to do the. The goal of this work is to develop a new model to predict the inflow performance relationship curve for gas condensate reservoirs.
The vertical line on the phase diagram shows the phase changes in. Assumption of mentioned conditions can be aggregated in the form of optimization problem. The liquid is sometimes called by an older name distillate, and sometimes simply oil. Pdf understanding gascondensate reservoirs navneet. In addition, data collected in the barnett shale area special inventory conducted by tceq was evaluated, a phone survey of texas condensate producers was conducted, and additional data on emissions estimates was obtained from several recent studies evaluating condensate. 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. It is possible to obtain a sample of the gasconden sate mixture as it exists in the reservoir by lowering a special container down into a well. According to the complexity of the reservoir fluid phase behavior, reservoir modeling is classified under two distinct groups. Well productivity in an iranian gascondensate reservoir. In a low permeability gas condensate reservoir, the 6 vertical wells have a slightly better performance than the 2 horizontal wells for the same amount of field gas production. Characterization of gas condensate reservoirs is a di. Pdf understanding the behaviors of gas condensate reservoirs. A full spectrum of gas reservoir engineering techniques is addressed and their application to a large variety of gas resource management options is discussed.
This leads to creation of three regions with different liquid saturations and as a result, a composite reservoir hashemi et al. Pdf reservoirs are categorized to black oil, volatile oil, gas. Various methods were addressed to remediate the productivity decline, for example, fracturing, gas injection, solvent injection and chemical treatment. New inflow performance relationship for gas condensate reservoirs. This study of gas condensate reservoirs included a survey of exxon and.
Simulation study of enhanced condensate recovery in a gas condensate reservoir iranian journal of chemical engineering, vol. Gas condensate reservoir petroleum reservoir gases. 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. Understanding of phase and fluid flow behavior relationships is essential if we want to make accurate engineering computations for gas condensate systems e. Summary this paper presents a generalized equation of state eos that represents several widely used cubic eoss. Reservoir engineers have been concerned about the impact of condensate blocking on productivity for many years. Production with gor 100,000 scfbbl is commonly called lean or dry gas. Gas injection techniques for condensate recovery and. Pdf with the current focus on liquidsrich shale plays lrs in north america and the importance of gas condensate reservoirs globally, there. Analysis of condensate banking dynamics in a gas condensate reservoir under different injection schemes. The experimental apparatus and data acquisition system were both tested with nitrogen.
The percentage of vapor decreases, but can increase again with continued. Production testing a gas condensate with low condensate formation in the reservoir when the bottomhole pressure is reduced below the dewpoint pressure. The term wet gas is sometimes used as more or less equivalent to gas condensate. Often times, it is safe to assume that reservoir fluid behavior is only a function of pressure and independent of composition. Engineer your gascondensate systems, reservoir to sales meter shah kabir chevron energy technology company spe 95531, 95528, 89753, 89754, 100384. 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. Interpretation of the unusual fluid distribution in the yufutsu gascondensate field kassem ghorayeb, spe, and abbas firoozabadi, spe, reservoir engineering research inst. Compositional modeling of gascondensate reservoirs. The depletion of gas condensate reservoirs to pressures below the. Engineer your gas condensate systems, reservoir to sales meter shah kabir chevron energy technology company spe 95531, 95528, 89753, 89754, 100384. A recovered from associated and non associated gas wells from lease separators or field. Hydrocarbon liquid dissolved in saturated natural gas that comes out of solution when the pressure drops below the dewpoint. New inflow performance relationship for gas condensate. Gas condensate fields is a single subsurface accumulation of gaseous hydrocarbons including gasoline and kerosene vapors and, less frequently, components with a higher molecular weight.
The answer requires a thorough understanding of what motivates mergers, a topic that continues to be hotly debated. Gas injection is an process applied to minimize the condensate drop out in the reservoir. Pope university of texas austin, texas alexander shandrygin moscow, russia. The api gravity of 10 is associated with very heavy, almost asphaltic, oils. The productivity of the well declined rapidly when the bottomhole p decreased below pd. Analysis of condensate banking dynamics in a gas condensate. A commercial simulator was then used to carry out numerical reservoir simulation of fluid flow in the north field. When the pressure in a gascondensate reservoir decreases to a certain point, called the saturation pressure or. Much of the pressure drop from condensate blockage occurs within a few feet of the wellbore, where flow rates and capillary numbers are very high. 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. A phase diagram is illustrated in the next picture.
188 1520 262 1333 1434 1288 47 1058 608 744 75 1413 526 1038 1444 695 1390 1196 1018 183 1581 344 1549 1279 62 1256 50 519 502 761 985 463 1505 323 1386 1206 584 50 1114 1226 244 368