Gas Condensate Research Articles

Structure, morphology and magnetic performance of (Fe65Co35) x @(Ni0.5Zn0.5Fe2O4)100–x nanocomposite thin films

A bi-magnetic phase (Fe65Co35)x@(Ni0.5Zn0.5Fe2O4)100–x nanocomposite thin film was created by combining Fe65Co35 alloy nanoclusters produced through plasma gas condensation with Ni0.5Zn0.5Fe2O4 thin film prepared via RF magnetron sputtering. The study revealed that the Fe65Co35 alloy nanoclusters, with an average particle size of approximately 6 nm, are surrounded by the amorphous ferrite phase, forming a granular ‘core–shell’ structure. As the proportion of Fe65Co35 alloy nanoclusters increased from 5.9 wt% to 35.4 wt%, the grain size of the nanocomposite thin films decreased from 24 nm to 10.4 nm. Magnetic analysis demonstrated that the nanocomposite thin films displayed soft magnetic properties at room temperature. With an increase in Fe65Co35 content, the saturated magnetization of the nanocomposite thin films escalated from 68 emu cm−3 to 214 emu/cm3, significantly surpassing that of the corresponding NiZn ferrite films (∼17 emu/cm3). The fluctuation of coercivity is intricately linked to the grain size of the nanocomposite thin films, and at 24.5 wt% of Fe65Co35 alloy nanoclusters, the coercivity is minimized to 14 Oe. The ferromagnetic resonance spectra of the nanocomposite films exhibited some asymmetric broadening and shift. As the Fe65Co35 content increased, the resonance field initially decreased and then rose, while the resonance linewidth gradually decreased.

Effects of the Characterization Methods of Heptane Plus Components (C7+) on the Phase Behavior of Volatile Fluids

For reservoir fluids with strong volatile tendencies, such as gas condensate and volatile oil, the determination of the characteristic parameters of the equation of state has a great influence on the fluid phase behavior and subsequent reservoir engineering, production engineering, and surface facilities design calculations. However, the process of characterizing reservoir fluid lacks a unified and standardized procedure, and the methods are largely empirical and rather complicated. In this paper, three main stages are defined for the characterization of the equation of state parameters for these volatile reservoir fluids, including (1) determining the C7+ distribution, (2) calculating the equation of state parameters for the C7+ single-carbon component, and (3) lump components. The typical calculation methods in each step and their effects on the fluid phase behavior calculations are quantitatively analyzed and compared. Finally, the workflow and the suitable characterization methods for gas condensate and volatile oil phase behavior calculations are selected. The results show that C7+ distribution and C7+ single carbon component properties have a greater influence on the phase behavior prediction of condensate gas and volatile oil, while the lumping of C7+ single carbon component has relatively little influence.

Numerical Simulation Study on Optimization of Development Parameters of Condensate Gas Reservoirs

Due to the retrograde condensation phenomenon in the development process, the fluid phase change is complex, and it becomes particularly difficult to accurately describe the fluid flow characteristics and residual oil and gas distribution characteristics during the development of condensate gas reservoirs. It is difficult to select the development program and subsequent dynamic adjustment for the efficient, reasonable, and sustainable development of condensate gas reservoirs. In this paper, the phase characteristics of condensate gas reservoirs are clarified; the basic fluid model is created by using computer modeling, using Win-Prop; and in view of the characteristics of the target condensate gas reservoirs, the CMG (Computer Modeling Group) numerical simulation method is applied to study the effects of six factors, the thickness of the reservoir, permeability, porosity, rock compression coefficient, the ratio of the vertical permeability to the horizontal permeability, and the injection of different media, on the development effect through the study of different development parameters of gas condensate reservoirs. The purpose of this study is to provide guidance for the rational development of condensate gas reservoirs in practical production.

Vilyui and Priverkhoyansk Composite Tectono-Sedimentary Elements, Northeastern East Siberia

A vast region of the Northeastern Siberia west of the Verkhoyansk Range includes two large sedimentary basins, Vilyui and Priverkhoyansk. Combined, these basins constitute the Lena-Vilyui Petroleum Province, which contains the largest gas reserves in the northeastern Asia. Both basins have a long and complex geological history that resulted in the accumulation of over 14 km-thick succession of Upper Proterozoic, Paleozoic, Mesozoic and Cenozoic sedimentary rocks. According to the volume's terminology, we subdivide this sedimentary body into two composite tectono-sedimentary elements (CTSE), the Vilyui and Priverkhoyansk (VI CTSE and PV CTSE), which closely correspond to the same-named basins. The CTSEs consist of ten distinct tectono-sedimentary elements (TSEs), each representing a distinct tectonic setting. This region has been studied very irregularly. In total, more than 400 deep wells have been drilled, mostly within the VI CTSE and only a few tens - in the PV CTSE. Eleven gas and gas condensate accumulations have been discovered in the VI CTSE. The PV CTSE remains poorly explored with only two commercial discoveries made as of the present-day.

A Comparative Analysis of the Prediction of Gas Condensate Dew Point Pressure Using Advanced Machine Learning Algorithms

Dew point pressure (DPP) emerges as a pivotal factor crucial for forecasting reservoir dynamics regarding condensate-to-gas ratio and addressing production/completion hurdles, alongside calibrating EOS models for integrated simulation. However, DPP presents challenges in terms of predictability. Acknowledging these complexities, we introduce a state-of-the-art approach for DPP estimation utilizing advanced machine learning (ML) techniques. Our methodology is juxtaposed against published empirical correlation-based methods on two datasets with limited sizes and diverse inputs. With superior performance over correlation-based estimators, our ML approach demonstrates adaptability and resilience even with restricted training datasets, spanning various fluid classifications. We acquired condensate PVT data from publicly available sources and GeoMark RFDBASE, encompassing dew point pressure (the target variable), as well as compositional data (mole percentages of each component), temperature, molecular weight (MW), and specific gravity (SG) of heptane plus, which served as input variables. Before initiating the study, thorough assessments of measurement quality and results using statistical methods were conducted leveraging domain expertise. Subsequently, advanced ML techniques were employed to train predictive models with cross-validation to mitigate overfitting to the limited datasets. Our models were juxtaposed against the foremost published DDP estimators utilizing empirical correlation-based methods, with correlation-based estimators also trained on the underlying datasets for equitable comparison. To improve outcomes, pseudo-critical properties and artificial proxy features were utilized, leveraging generalized input data.

On the transition of liquid dispersion states and their physical-thermodynamic nature in the development of gas-condensate reservoirs in depletion mode

While the depletion regime for gas-condensate fields may be more cost-effective, it often results in the loss of hydrocarbon condensate, which is economically more valuable than gas, and leads to the inefficient exploitation of the field in terms of condensate production. Therefore, the development of effective exploitation systems for such fields is essential. Effective exploitation of gas-condensate fields involves achieving maximum hydrocarbon condensate production in addition to maximum gas production. From this aspect, managing the condensate factor of reservoir system during the depletion regime is a critical issue. The article experimentally and theoretically investigates the phase transitions or mutual dispersion occurrences between hydrocarbon liquid and gas mixtures that occur with a decrease in pressure at reservoir temperature during the natural depletion of gas-condensate fields. During the exploitation of gas-condensate fields, it has been observed that even at pressures higher than retrograde condensation pressure, the hydrocarbon system undergoes complex phase transitions, resulting in distinct transition points due to the mutual dispersion of hydrocarbon liquid and gas. Additionally, pVT studies conducted in the laboratory have made it possible to determine the transition points of the reservoir fluid in the “liquid in gas” and vice versa dispersion states. The research has demonstrated that dependance of gas condensate factor on pressure under given isothermal natural conditions more clearly reflects the retrograde and maximum condensation, also dispersion points of the liquid components. It was found that proportionality coefficient between condensate ratio and pressure of gas-condensate system is unique for each production facility under isothermal conditions and characterizes the stability of fluid’s dispersion state. The importance of considering such transition points when designing gas-condensate field development projects has been highlighted.

Study on the condensate gas phase behavior in Nano-porous media

The pore size in shale has reached the nanoscale. The phase behavior of fluids in nanopores deviates from classical theory, making conventional phase theory inapplicable to shale reservoirs. It is thus of great significance to clarify the phase behavior at the nanometer pore scale in shale. Based on the shale reservoir in the Kaybob of the Duvernay shale, Canada, 6 nm and 10 nm cubic model systems were constructed, and a microscopic physical model was prepared included pathways at 10 nm, 40 nm, 500 nm, and micrometer scale. The fluid phase behavior in nanopores was studied using molecular simulations and nanofluidic chip experiments. The results show that during the retrograde condensation process, the condensate gas in small-scale pores condenses first and is less likely to evaporate as the pressure decreases. The conclusions drawn are: (1) In nanopores, the dew point pressure of condensate gas is higher than that of the bulk phase, and the smaller the scale of nanopores, the higher the dew point pressure. (2) The volume ratio of condensate in nanopores is higher, increasing as pore size decreases. (3) The condensation rate of condensate in nanoporous media varies slowly with pressure drop; During evaporation, the condensation rate of condensate in small pores varies more slowly with pressure drop compared to the bulk phase but is faster in large pores.

Nucleation mechanism of methane heterogeneous condensation under different driving forces

Clarifying alkane gas condensation characteristics is crucial to designing and optimizing liquefaction heat exchangers, which imposes higher demands on the microscopic understanding of alkane heterogeneous condensation. Thus, in this study, the condensation process of methane nucleation under different driving forces is investigated by molecular dynamics (MD) simulations. The dynamics characteristics of nucleation in methane heterogeneous condensation are analyzed by varying initial gas-phase pressure, cold wall temperature, and ethane content. The results showed that increasing the initial gas-phase pressure enhances intermolecular interactions, which alter the cluster formation path and significantly increase the methane gas nucleation rate from 1.997 × 1033/(m3·s) to 1.068 × 1034/(m3·s). While lowering the cold wall temperature promotes condensation by weakening the thermal motion of the gas molecules. Once condensation nuclei form in the system, the lower temperature conditions from lowering the cold wall temperature result in a higher growth rate of the clusters. Additionally, the addition of easily condensable component ethane can improve the condensation nucleation characteristics of low-saturated methane gas, facilitating the liquefaction of methane. This study aims to provide a microscopic understanding of the advancement of gas liquefaction technology by investigating the heterogeneous nucleation of alkane under different conditions from a microscopic perspective.

Cavitating Bubbles in Condensing Gas as a Means of Forming Clumps, Chondrites, and Planetesimals

Vaporized metal, silicates, and ices on the verge of recondensing into solid or liquid particles appear in many contexts: behind shocks, in impact ejecta, and within the atmospheres and outflows of stars, disks, planets, and minor bodies. We speculate that a condensing gas might fragment, forming overdensities within relative voids, from a radiation–condensation instability. Seeded with small thermal fluctuations, a condensible gas will exhibit spatial variations in the density of particle condensates. Regions of higher particle density may radiate more, cooling faster. Faster cooling leads to still more condensation, lowering the local pressure. Regions undergoing runaway condensation may collapse under the pressure of their less condensed surroundings. Particle condensates will compactify with collapsing regions, potentially into macroscopic bodies (planetesimals). As a first step toward realizing this hypothetical instability, we calculate the evolution of a small volume of condensing silicate vapor—a spherical test “bubble” embedded in a background medium whose pressure and radiation field are assumed fixed for simplicity. Such a bubble condenses and collapses upon radiating its latent heat to the background, assuming that its energy loss is not stopped by background irradiation. Collapse speeds can range up to sonic, similar to cavitation in terrestrial settings. Adding a noncondensible gas like hydrogen to the bubble stalls the collapse. We discuss whether cavitation can provide a way for millimeter-sized chondrules and refractory solids to assemble into meteorite parent bodies, focusing on CB/CH chondrites whose constituent particles likely condensed from silicate/metal vapor released from the most energetic asteroid collisions.

Методические аспекты анализа факторов, влияющих на испарение газоконденсата при подводных выбросах

The process of evaporation of gas condensate during emergency blowout of an underwater well has been studied insufficiently. The influence of various factors on the size of the zone of intense evaporation of gas condensate during the blowout of a shallow gas condensate well requires detailed consideration. In this paper, the researchers, using mathematical modeling, have analyzed this effect for wells with parameters characteristic of the Russian Arctic region. They have performed the calculations using the SPILLMOD model and the Lagrangian element evolution model. A significant dependence of the gas outlet area size and the gas blowout size on the sea surface on the values of the gas plume involvement parameter in the model has been revealed, and at the same time a weak dependence of the size of the zone of intense evaporation of gas condensate on this parameter. The values of the mass flow rate of gas condensate in the discharge, as well as its fractional composition, have a noticeably greater effect.

On Dunkl-Bose-Einstein Condensation in Harmonic Traps

The use of the Dunkl derivative, defined by a combination of the difference-differential and reflection operators, allows the classification of the solutions according to even and odd solutions. Recently, we considered the Dunkl formalism to investigate the Bose-Einstein condensation of an ideal Bose gas confined in a gravitational field. In this work, we address another essential problem and examine an ideal Bose gas trapped by a three-dimensional harmonic oscillator within the Dunkl formalism. To this end, we derive an analytic expression for the critical temperature of the N particle system, discuss its value at large-N limit andfinally derive and compare the ground state population with the usual case result. In addition, we explore two thermal quantities, namely the Dunkl-internal energy and the Dunkl-heat capacity functions.

Air Injection into Condensate Reservoirs in the Middle and Late Stages Increases Recovery with Thermal Miscible Mechanism

Summary Condensate gas reservoirs in the middle and late stages of development are faced with problems such as formation pressure reduction, serious retrograde condensation, and oil and gas seepage channel plugging, which make it difficult to further improve oil and gas recovery by conventional development methods. For this kind of condensate gas reservoir, in this paper we put forward air injection technology as a development means, taking the K condensate gas reservoir in the Tarim Oilfield as the research object. We explored the thermal oxidation characteristics and displacement efficiency of condensate oil/volatile oil by air injection through the thermal oxidation displacement experiment. In addition, we determined quantitatively the minimum miscibility pressure (MMP) of oil samples at high temperature and the correlation between MMP and temperature through a high-temperature, high-pressure slimtube experiment, and clarified the mechanism of “thermally assisted miscible” through fine full-component numerical simulations under high-temperature and high-pressure conditions, which indoor experiments could not achieve. The results showed that condensate oil/volatile oil can form a stable thermal front by injecting air, and the oil displacement efficiency is more than 90%. The MMP of flue gas produced by condensate oil and oxidation reaction decreases gradually with temperature increase, and the MMP is only 11 MPa at 260°C. The high temperature formed by oxidation heat release forces the oil phase into the gas phase, and the extraction of flue gas makes C2-C4 in the oil phase increase continuously, both of which promote the realization of heat-assisted evaporation miscible phase. This thermal-assisted miscible-phase mechanism makes air injection displacement technology an innovative replacement technology for greatly improving the recovery efficiency of condensate gas reservoirs in the middle and late development stages.

THE STATE OF THE ARCTIC PROBLEMS OF THE NENETS AUTONOMOUS OKRUG AND PROSPECTS OF THEIR SOLUTION

The article analyses the first stage of the Nenets Autonomous Okrug’s (NAO) implementation of the 7 tasks set out in the Strategy for Developing the Russian Arctic Zone and Ensuring National Security until 2035. Particular attention is paid to the study of the development of the project for the construction of the deep-water seaport of Indiga and the Sosnogorsk – Indiga railway, transport infrastructure development, including the reconstruction of the seaport and airports. The article analyses the activities on dredging on the Pechora River, construction of a highway, the development of oil and gas condensate mineral resource centers, based on the NAO fields, including the development of new ones. The problem of geological study and development of mineral resource base of solid minerals is considered. The article examines the population dynamics, the experience of Arctic residents, and their tax benefits. The author separately considers the construction of an agroindustrial park and the implementation of export-oriented projects involving deep processing of venison, as well as the issues of developing a tourism cluster in the region. It is concluded that, with the exception of the completion of the Naryan-Mar – Usinsk highway and the intensive development of tourism, the rest of the Arctic projects are at the initial stage, their development hampered by the lack or complete absence of funding.

Time Dependent Spectral Ratio Technique for Micro-seismic Exploration in the Niger Delta Region of Nigeria

Abstract: Since the discovery of the hydrocarbon micro-tremors, there have been numerous efforts to understand the causes of these microseisms related to oil and gas. A spectral ratio (SR) time-dependent equation was derived based on geological principles. The equation showed tremendous success in analyzing multi-layered geological terrain and estimating the spectral ratio in the Niger Delta region of Nigeria. This study seeks to develop a reliable model using standard seismic reflection data to analyze microseismic datasets from hydrocarbon reservoirs. Type A-SR acts over a longer duration and can be used to determine hydrocarbon reservoirs. Type B-SR acts in a short time with maximum impact. It can be used to determine gas condensate flow in the hydrocarbon reservoir. It is recommended that this technique be applied in real time to ascertain its accuracy. Keywords: Niger Delta, Microseismic, Amplitude, Special ratio, Geology.

Study on Nonlinear Parameter Inversion and Numerical Simulation in Condensate Reservoirs

The B6 metamorphic buried hill condensate gas reservoir exhibits a highly compact matrix, leading to a rapid decline in bottom-hole pressure during initial production. The minimal difference between formation and saturation pressures results in severe retrograde condensation, with multiphase flow further increasing resistance. Conventional numerical simulations often overestimate reservoir energy supply due to their failure to account for this additional resistance, leading to inaccuracies in bottom-hole pressure predictions and gas–oil ratio during history matching. To address these challenges, this study conducted research on nonlinear numerical simulation for buried hill condensate gas reservoirs and established a method for calculating a multiphase pressure sweep range based on the well testing theory. By correcting and fitting the pressure propagation boundaries with numerical simulation, the nonlinear flow parameters applicable to the B6 gas field were inversed. This study revealed that conventional Darcy flow is inadequate for predicting pressure propagation boundaries and that it is possible to reasonably characterize the pressure sweep range through nonlinear flow. This approach resulted in an improvement in the accuracy of historical matching for bottom-hole pressure and gas–oil ratio, which improve the historical fitting accuracy to 85%, providing valuable insights for the development of similar reservoirs.

Geochemical Characteristics and Origin of Natural Gas in the Middle of Shuntuoguole Low Uplift, Tarim Basin: Evidence from Natural Gas Composition and Isotopes

Multiple types of reservoirs, including volatile oil reservoirs, condensate gas reservoirs, and dry gas reservoirs, have been discovered in ultra-deep layers buried at depths greater than 7500 m. Understanding the genetic types of natural gas is of utmost importance in evaluating oil and gas exploration potential. The cumulative proved reserves of the super deep layer in the Shuntuoguole low uplift area of the Tarim Basin exceed 1 × 108 t (oil equivalent). The origin, source, and accumulation characteristics of natural gas still remain a subject of controversy. By analyzing the composition and carbon isotope of natural gas, a detailed investigation was conducted to examine the unique geochemical and reservoir formation characteristics of the Ordovician ultra-deep natural gas within different fault zones in the middle region of the Shuntuoguole low uplift. It was determined that most of the natural gas in this area is displaying a characteristic of wet gas with a drying coefficient ranging from 0.41 to 0.99. The carbon isotope composition of methane in the gas reservoir shows relatively light values, ranging from −49.4‰ to −42‰. The carbon and hydrogen isotopes of the components are distributed in a positive order. The natural gas is oil type gas, which is derived from marine sapropelic organic matter and has a good correspondence with the lower Yuertusi formation. The maturity of natural gas in Shunbei No. 1 and No. 5 fault zones is about 1.0%, which is the associated gas of normal crude oil, while the maturity of No. 4 and No. 8 fault zones is higher than 1.0%, which is the mixture of kerogen pyrolysis gas and crude oil pyrolysis gas. The variations in the drying coefficient and carbon isotope composition of the natural gas provide evidence for the migration patterns within the Shuntuoguole low uplift central region. It indicates that the Shunbei No. 5 and No. 8 fault zones have likely migrated from south to north, while the No. 4 fault zone has migrated from the middle to both the north and south sides. These migration patterns are primarily controlled by high and steep strike-slip faults, which facilitate the vertical migration of natural gas along fault planes. Consequently, the gas accumulates in fractured and vuggy reservoirs within the Ordovician formation.

Novel amine emissions control methods for CO2 capture based on reducing amine concentration in the scrubbing liquid

Piperazine (PZ) activated 2-amino-2-methyl-1-propanol (AMP) is a high-performance solvent for CO2 capture that has undergone long-term pilot test. This study explores its vapor amine emissions characteristics on Aspen Plus. It was found that the steady-state amine concentration in the water wash (WW) is a crucial factor affecting emissions, determined by the amine-to-water ratio obtained from flue gas and feed water. Under optimized conditions, vapor amine emissions were reduced from 1768 mg/Nm3 after the absorber to 1.46 mg/Nm3 after two WW sections. Two novel amine control methods were proposed based on the approach of lowering the amine concentration in the scrubbing liquid. Staged condensation of the stripper gas provides super low amine (0.06 wt%) feed water to the WW, further reducing vapor amine emissions by an order of magnitude. The Cooling Dry Bed (CDB) can achieve amine emission control effects comparable to two WW sections with only 20 % of the theoretically calculated interfacial area. This process has a lower total packing height and does not require liquid collection trays, significantly reducing the construction height and load of the column.

Effectiveness of Natural Gas Condensate as a Viable Solvent in ES-SAGD Processes: An Experimental Investigation Using a 3-D Physical Model

Effectiveness of Natural Gas Condensate as a Viable Solvent in ES-SAGD Processes: An Experimental Investigation Using a 3-D Physical Model

Evaluation of Key Development Factors of a Buried Hill Reservoir in the Eastern South China Sea: Nonlinear Component Seepage Model Coupled with EDFM

The HZ 26-B buried hill reservoir is located in the eastern part of the South China Sea. This reservoir is characterized by the development of natural fractures, a high density, and a complex geological structure, featuring an upper condensate gas layer and a lower volatile oil layer. These characteristics present significant challenges for oilfield exploration. To address these challenges, this study employed advanced embedded discrete fracture methods to conduct comprehensive numerical simulations of the fractured buried hill reservoirs. By meticulously characterizing the flow mechanisms within these reservoirs, the study not only reveals their unique characteristics but also establishes an embedded discrete fracture numerical model at the oilfield scale. Furthermore, a combination of single-factor sensitivity analysis and the Pearson correlation coefficient method was used to identify the primary controlling factors affecting the development of complex condensate reservoirs in ancient buried hills. The results indicate that the main factors influencing the production capacity are the matrix permeability, geomechanical effects, and natural fracture length. In contrast, the impact of the threshold pressure gradient and bottomhole flow pressure is relatively weak. This study’s findings provide a scientific basis for the efficient development of the HZ 26-B oilfield and offer valuable references and insights for the exploration and development of similar fractured buried hill reservoirs.

A MODEL FOR FORECASTING DEW POINT PRESSURE IN NIGER DELTA CONDENSATE RESERVOIRS USING CONSTANT VOLUME DEPLETION TESTS DATA

The dew point pressure plays a critical role in developing gas condensate reservoirs. It is a crucial factor used in fluid characterisation, performance estimation of gas reservoirs, and design of production systems. However, the composition of gas condensate fluid varies from one location to another, and thus, empirical correlations have been developed to determine the dew point pressure without conducting routine tests. As a result, correlations that are solely useful in the region where they were developed and analysed are developed. This work developed an empirical correlation using data from gas condensate wells in the Niger Delta using multiple linear regression. The model was developed using the Analytical Tools and techniques in Microsoft Excel. To develop the model, we utilised 63 data sets from the Constant Volume Depletion (CVD) experiment, which involved gas condensates from resources in the Niger Delta. The model comprises an empirical correlation that estimates the dew point pressure for gas condensate reservoirs. It uses compositional information of the fluid and reservoir temperature as input parameters. The correlation is derived through multiple regression analyses. Comparing the prediction accuracy of formulas based on the developed model and other conventional methods indicated that this model is more accurate than other statistical methods in predicting DPP within the Niger Delta region. This model can produce more accurate results than other estimation methods when working under limited field information and time constraints. The correlation developed in this process has a coefficient of determination of R2=0.869 and an Average Absolute Relative Error (AARE) of -2.0767%, along with a root mean square of 195279, indicating a high level of reliability in the proposed correlation.