Forecasting Hydrocarbon Production at Gas Condensate Fields Considering Phase Transformations of Reservoir Systems

2021 ◽  
Author(s):  
Yefim Semenovich Bikman

Abstract Based on the results of PVT studies, a methodology for estimating hydrocarbon recovery at various stages of a gas condensate field development, depending on the current weighted average reservoir pressure in the gas drive, is considered. In this case, the physical processes related to the phase transformations of the reservoir gas condensate mixture with a decrease in reservoir pressure in the deposit are assumed identical in the PVT bomb. That is, the effect of the porous medium is neglected. This allows describing the processes of phase transformations with the same equation of material balance, based on which it is possible to forecast hydrocarbon recovery at gas condensate fields, and provide a control over the results of phase transformation modelling of the reservoir gas condensate mixture in phase balance bomb (PVT bomb).


2007 ◽  
Vol 10 (01) ◽  
pp. 43-49 ◽  
Author(s):  
John Paul Spivey ◽  
Peter P. Valko ◽  
William D. McCain

Summary The coefficient of isothermal compressibility (oil compressibility) is defined as the fractional change of oil volume per unit change in pressure. Though the oil compressibility so defined frequently appears in the partial-differential equations describing fluid flow in porous media, it is rarely used in this form in practical engineering calculations. Instead, oil compressibility is usually assumed to be constant, allowing the defining equation to be integrated over some pressure range of interest. Thus, the oil compressibility in the resulting equations should be regarded as a weighted average value over the pressure range of integration. The three distinct applications for oil compressibility in reservoir engineering are (1) instantaneous or tangent values from the defining equation, (2) extension of fluid properties from values at the bubblepoint pressure to higher pressures of interest, and (3) material-balance calculations that require values starting at initial reservoir pressure. Each of these three applications requires a different approach to calculating oil compressibility from laboratory data and in developing correlations. The differences among the values required in these three applications can be as great as 25%. Most published correlations do not indicate the particular application to which the proposed correlation applies. A correlation equation for oil compressibility has been developed using more than 3,500 lines of data from 369 laboratory studies. This correlation equation gives the average compressibility between the bubblepoint pressure and some higher pressure of interest. Equations to calculate appropriate values of compressibility for the other two applications are presented. Introduction The equation defining the coefficient of isothermal compressibility at pressures above the bubblepoint pressure is rather simple:(Equation 1) However, in application the situation becomes somewhat complex. Usually the equation is integrated by separating variables:(Equation 2) Moving oil compressibility outside the integral sign requires the assumption that it is constant. Because it is not constant, the use of this equation requires a value of oil compressibility that is a pressure-weighted average across the pressure range used in the calculations. There are three applications for oil compressibility in reservoir engineering:The defining equation, for which the oil compressibility should be calculated as a single value at the pressure of interest, often used in pressure-transient analysis.The extension of fluid properties from correlations starting at the bubblepoint pressure to pressures above the bubblepoint pressure. This application is also used in black-oil reservoir simulation.The use of oil compressibility in black-oil material-balance equations in which the starting point is the initial reservoir pressure. Values of oil compressibility should be calculated from laboratory data with these applications in mind. Most published correlations for oil compressibility do not indicate the particular situation to which the correlation applies, although values calculated for these three applications can differ significantly. For example, Fig. 1 gives values of oil compressibility calculated with the constant-composition-expansion data from a widely available black-oil laboratory report (Reservoir Fluid Study 1988). Two things are readily apparent. First, coefficients of isothermal compressibility are not constant as pressure changes. Second, the three applications require values that differ by up to 25%.



2021 ◽  
Vol 11 (3) ◽  
pp. 1081-1091
Author(s):  
A. A. Feyzullayev ◽  
I. Lerche ◽  
I. M. Mamedova ◽  
A. G. Gojayev

AbstractThe scientific basis of the paper is the concept of renewability of oil and gas resources. In accordance with this concept, the purpose of this paper is to estimate the volumetric rate of natural replenishment of the reservoir with oil and gas using the example of long-developed Bibieybat oil and Garadag gas condensate fields in the South Caspian Basin (SCB). The methodological approach of this assessment is based on the authors' assumption that at the late stage of field development, the recoverable amount of hydrocarbon fluids is compensated by the amount of their natural inflow, as a result of which oil or gas production stabilizes. The analysis of the dynamics of hydrocarbon production for the Bibieybat oil field covered the period from 1935 to 2018, and for the Garadag gas condensate field from 1955 to 1979. The rate of natural oil replenishment calculated for 29 operating facilities of the Bibieybat field varies per well within 0.32–1.4 ton/day (averaging 0.76 ton/day) or about 277 ton/year. The rate of natural gas inflow at the Garadag gas condensate field is about 5.2 thousand m3/day per well.



Author(s):  
S. V. Krivulya ◽  
S. V. Matkivskyi ◽  
Ye. S. Bikman ◽  
O. R. Kondrat ◽  
O. V. Burachok

Special features of tight gas reserves determination, based on material balance method, were characterized, since reliability of initial hydrocarbons in place determination plays important role in future field development planning, particularly on recovery rate, wells to be drilled, capital expenditures, surface facilities etc. Using the synthetic 3D model of gas reservoir, different development scenarios were evaluated according to the different spatial distribution patterns of petrophysical properties within the reservoir. Analyzing the obtained results, the authors fully confirmed an assumption made, that significant heterogeneity of reservoir properties makes a great impact on the shape of pseudo reservoir pressure curve vs cumulative gas produced and introduces significant errors into determination of initial gas in place. At the late stages of the development, the slope of P/z straight line changes, and this allows determination of much greater reserves’ volumes. Usage of pseudo reservoir pressure vs cumulative produced gas for determination of drained reserves in tight gas formation is especially risky, because the production data can indicate the true volumes of gas in place, only after the majority of the gas been produced. In most cases, the development period to acquire necessary data for correct volumes in place estimation exceeds the planning period. This factor introduces the significant error into future field development during the planning phase. Due to that, at the initial development stages, the error in drained volumes estimation can account for 50% out of true initial volumes in place. Based on conducted research, the potential error evaluation for tight gas reservoirs initial gas in place determination with decline pressure material balance method was performed. According to the results of computer simulation, the error can account for 25% from true initial gas in place in simulation model. This error significantly excesses the acceptable limits and can lead to wrong decisions in development planning



2021 ◽  
Author(s):  
Anna E. Gubanova ◽  
Bulat A. Khabibullin ◽  
Denis M. Orlov ◽  
Dmitry A. Koroteev

Abstract To reduce inefficient costs and environmental risks, oil companies strive to optimize the process of hydrocarbon production at all stages of field development, including geological and technical works at wells. In particular, it is important to predict fluid production with high accuracy. 3D hydrodynamic modeling is a generally accepted technique for solving this problem. It provides reliable results but requires many input data, computational resources, and time for calculations. Since the decision-making process has to be reactive, it is necessary to develop a simultaneously precise and prompt predictive instrument for quick forecasts of liquid production. The most promising tools for these purposes are proxy models based on solving the material balance equation. They adapt to the existing historical data even without PVT properties and reservoir data. Some of the most popular approaches are proxy models such as Capacitance Resistance Models (CRM). CR-type model is a material balance-based flow model, which provides preferable transmissibility trends, the presence of sealing or leaking faults with compressibility effects in consideration, and dissipation between injector-producer pairs. It is a data-driven model with adjustable time constants and interwell connectivity parameters. Before the model tuning, all parameters must be initialized with analytical or random approximations, and then they can be found by an appropriate optimization procedure. Historical-based Capacitance Models can be applied to poorly studied fields. Besides, they give an opportunity to rapidly optimize field development strategy by making calculations with different well exploitation parameters. They only require historical data of hydrocarbon production volumes, injection profiles, and bottom-hole pressure dynamics as input data. One of the main is that properties in the interwell space are estimated approximately and considered to be constant throughout the entire development history. However, this is a weak assumption in the case of including well interventions and stimulations. Thus, the main goal of this work is to adjust coefficients online to changes in well operation modes, introducing new wells or shut-in the existing ones. Since the governing equation includes the considered CRM improvement, users can perform optimization over different timespans, including "special" intervals. As a result, weighting connectivity parameters of the model can be depicted on a map of well interactions versus time.



Author(s):  
Angang Zhang ◽  
Zifei Fan ◽  
Lun Zhao ◽  
Anzhu Xu

Maintaining the reservoir pressure by gas injection is frequently adopted in the development of gas condensate reservoir. The aim of this work is to investigate the phase behavior of condensate oil and remaining condensate gas in the formation under gas injection. The DZT gas condensate reservoir in East China is taken as an example. The multiple contact calculation based on cell-to-cell method and phase equilibrium calculations based on PR Equation of State (EOS) were utilized to evaluate the displacement mechanism and phase behavior change. The research results show that different pure gas has different miscible mechanism in the displacement of condensate oil: vaporizing gas drive for N2 and CH4; condensing gas drive for CO2 and C2H6. Meanwhile, there is a vaporing gas drive rather than a condensing gas drive for injecting produced gas. When the condensate oil is mixed with 0.44 mole fraction of produced gas, the phase behavior of the petroleum mixture reverses, and the condensate oil is converted to condensate gas. About the reinjection of produced gas, the enrichment ability of hydrocarbons is better than that of no-hydrocarbons. After injecting produced gas, retrograde condensation is more difficult to occur, and the remaining condensate gas develops toward dry gas.



Author(s):  
R.R. Haliulin ◽  
◽  
S.N. Zakirov ◽  
A.H. Kha ◽  
N.E. Vedernikov ◽  
...  


2021 ◽  
Author(s):  
Pavel Dmitrievich Gladkov ◽  
Anastasiia Vladimirovna Zheltikova

Abstract As is known, fractured reservoirs compared to conventional reservoirs have such features as complex pore volume structure, high heterogeneity of the porosity and permeability properties etc. Apart from this, the productivity of a specific well is defined above all by the number of natural fractures penetrated by the wellbore and their properties. Development of fractured reservoirs is associated with a number of issues, one of which is related to uneven and accelerated water flooding due to water breakthrough through fractures to the wellbores, for this reason it becomes difficult to forecast the well performance. Under conditions of lack of information on the reservoir structure and aquifer activity, the 3D digital models of the field generated using the hydrodynamic simulators may feature insufficient predictive capability. However, forecasting of breakthroughs is important in terms of generating reliable HC and water production profiles and decision-making on reservoir management and field facilities for produced water treatment. Identification of possible sources of water flooding and planning of individual parameters of production well operation for the purpose of extending the water-free operation period play significant role in the development of these reservoirs. The purpose of this study is to describe the results of the hydrochemical monitoring to forecast the water flooding of the wells that penetrated a fractured reservoir on the example of a gas condensate field in Bolivia. The study contains data on the field development status and associated difficulties and uncertainties. The initial data were results of monthly analyses of the produced water and the water-gas ratio dynamics that were analyzed and compared to the data on the analogue fields. The data analysis demonstrated that first signs of water flooding for the wells of the field under study may be diagnosed through the monitoring of the produced water mineralization - the water-gas ratio (WGR) increase is preceded by the mineralization increase that may be observed approximately a month earlier. However, the data on the analogue fields shows that this period may be longer – from few months to two years. Thus, the hydrochemical method within integrated monitoring of development of a field with a fractured reservoir could be one of the efficient methods to timely adjust the well operation parameters and may extend the water-free period of its operation.



2021 ◽  
Author(s):  
Oleksandr Doroshenko ◽  
Miljenko Cimic ◽  
Nicholas Singh ◽  
Yevhen Machuzhak

Abstract A fully integrated production model (IPM) has been implemented in the Sakhalin field to optimize hydrocarbons production and carried out effective field development. To achieve our goal in optimizing production, a strategy has been accurately executed to align the surface facilities upgrade with the production forecast. The main challenges to achieving the goal, that we have faced were:All facilities were designed for early production stage in late 1980's, and as the asset outdated the pipeline sizes, routing and compression strategies needs review.Detecting, predicting and reducing liquid loading is required so that the operator can proactively control the hydrocarbon production process.No integrated asset model exists to date. The most significant engineering tasks were solved by creating models of reservoirs, wells and surface network facility, and after history matching and connecting all the elements of the model into a single environment, it has been used for the different production forecast scenarios, taking into account the impact of infrastructure bottlenecks on production of each well. This paper describes in detail methodology applied to calculate optimal well control, wellhead pressure, pressure at the inlet of the booster compressor, as well as for improving surface flowlines capacity. Using the model, we determined the compressor capacity required for the next more than ten years and assessed the impact of pipeline upgrades on oil gas and condensate production. Using optimization algorithms, a realistic scenario was set and used as a basis for maximizing hydrocarbon production. Integrated production model (IPM) and production optimization provided to us several development scenarios to achieve target production at the lowest cost by eliminating infrastructure constraints.





2018 ◽  
pp. 11-20 ◽  
Author(s):  
Yu. V. Vasilev ◽  
D. A. Misyurev ◽  
A. V. Filatov

The authors created a geodynamical polygon on the Komsomolsk oil and gas condensate field to ensure the industrial safety of oil and gas production facilities. The aim of its creation is mul-tiple repeated observations of recent deformation processes. Analysis and interpretation of the results of geodynamical monitoring which includes class II leveling, satellite observations, radar interferometry, exploitation parameters of field development provided an opportunity to identify that the conditions for the formation of recent deformations of the earth’s surface is an anthropogenic factor. The authors identified the relationship between the formation of subsidence trough of the earth’s surface in the eastern part of the field with the dynamics of accumulated gas sampling and the fall of reservoir pressures along the main reservoir PK1 (Cenomanian stage).



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