Fluid Expansion Research Articles

Modelo de simulación numérica para un arreglo de cinco pozos invertidos en un yacimiento sub - saturado

El estudio tuvo como objetivo generar un modelo de simulación numérica para un arreglo de cinco pozos invertidos de un yacimiento sub-saturado con expansión de roca - fluido como su principal energía de producción primaria. La investigación se enmarco en un enfoque mixto (cualitativo-cuantitativo) comenzando con una descripción de los parámetros fundamentales para la investigación como la geología regional del área, litología, arreglo de cinco pozos invertidos, condiciones operacionales tales como, la tasa de producción y presiones de fondo, curvas de permeabilidad relativa, análisis PVT, propiedades roca-fluido. La población está conformada por 25 pozos perforados en el yacimiento LL-C4 de los cuales 8 son pozos inyectores y 17 pozos son productores, para realizar la simulación numérica se estableció una delimitación areal del yacimiento LL-C4. La investigación consta de dos variables que son el factor de recobro y el modelo de simulación numérica las cuales se desarrollan mediante el software IMEX de CMG (computer modelling group). Para la construcción de la malla sísmica se procedió a la selección el tipo de grid de simulación numérica para este estudio es una malla cartesiana, establecido el modelo estático se procedió a construir el modelo de producción primaria en donde se realizaron sensibilidades tomando en cuenta dos variables que son la tasa de producción y presiones de fondo. Entre los resultados más relevantes se tiene que a nivel de yacimientos la implementación de la inyección de agua en la recuperación secundaria del yacimiento LL-C4 el factor de recobro aumento de manera considerable manteniéndose las condiciones operacionales óptimas.

Paleo-pressure evolution and its origin in the Pinghu slope belt of the Xihu Depression, East China Sea Basin

Abstract The Xihu Depression in the East China Sea Basin is one of the prime gas and light oil-producing regions of eastern China. Overpressure evolution and origin in the sandstone reservoirs of the Pinghu (E2p) Formation in the Pinghu slope belt of the Xihu Depression were investigated through a combination of fluid inclusion analyses and basin numerical modeling, combined with measured pore pressures (drill stem and wireline formation tests), well loggings, gas geochemistry, and casting thin section data. Four oil inclusion types, exhibiting different API gravities and hydrocarbon gas inclusions, were identified, using inclusion petrography, microscopic fluorescence, and Raman spectra. Homogenization and ice melting temperatures of coeval aqueous inclusions, determined using microthermometry, combined with burial-thermal histories determined by basin numerical modeling, suggested multiple episodes of oil and natural gas charge in the E2p reservoirs, from the Miocene to the present day. Pore pressure evolution history, reconstructed with fluid inclusion PVTx analysis, indicated that the Pinghu Formation experienced three phases: overpressure generation, followed by overpressure release, and then further overpressure generation. The first phase of weak overpressure was generated during burial in the middle–late Miocene. Currently, it is hard to definitely determine the origin of the first phase of overpressuring. Nevertheless, it can be speculated that the origin may be related to disequilibrium compaction, oil generation and tectonic compression based on burial, tectonic and hydrocarbon generation histories. Following this, a sudden uplift of formations led to overpressure release in the late Miocene, and then, the second phase of moderate overpressure generation occurred during burial in the late Pliocene and Quaternary. Based on well-log signatures, vitrinite reflectance data of mudstones and gas geochemistry, combining with seismic analysis, the second phase of overpressuring was interpreted to have been mainly caused by fluid expansion, which resulted from local gas generation by kerogen maturation and long-distance vertical and lateral pressure transfer.

A Coupled Transient Wellbore/Reservoir-Temperature Analytical Model

Summary This work presents a new coupled transient wellbore/reservoir thermal analytical model, consisting of a combined reservoir/casing/tubing system. The analytical model considers flow of a slightly compressible, single–phase fluid in a homogeneous infinite–acting reservoir system and provides temperature–transient data for drawdown and buildup tests at any gauge location along the wellbore. The model accounts for Joule–Thomson (J–T), adiabatic–fluid–expansion, conduction, and convection effects. The wellbore–fluid mass density is modeled as a function of temperature, and the analytical solution makes use of the Laplace transformation to solve the transient heat–flow differential equation, accounting for a transient wellbore–temperature gradient ∂T/∂z. The solutions presented assume moderate– to high–permeability reservoirs and do not consider skin effects in the formation. Results of the analytical model are compared with those of a commercial thermal simulator and with those of available models in the literature. Our model provides more accurate transient–temperature–flow profiles along the wellbore in comparison with previous analytical models in the literature. Furthermore, a generalization of a well–known parameter–estimation method from transient–temperature data is provided.

Automatic localization of anatomical regions in medical ultrasound images of rheumatoid arthritis using deep learning.

The pace of population aging is growing faster worldwide. The quality of life of the aging population is mostly affected by rheumatic diseases. With the increasing rate of rheumatoid arthritis in the aging population, technological advances in the field of automatic image processing and analysis have paved way for automatic detection and diagnosis of arthritis based on how the grade of the synovial region is designed. The proposed method is based on spatial analysis using intensity-based approach to segment the skin border, thresholding and connectivity algorithm for bone region segmentation, hit-or-miss transform for bone line segmentation and distance measure with image profile to detect the joint region. After this process of localization, the synovial region is determined using the active contour technique. In arthritis condition, synovitis also occurs which is categorized into four different grades based on the fluid expansion in the synovial region. The different grades are defined and analyzed through deep learning. Convolutional neural network in a deep learning algorithm is used to diagnose the particular grade of synovitis to describe the nature of arthritis. With these results, a module to detect the nature of arthritis automatically is defined.

Towards a plastic engine: Low—temperature tribology of polymers in reciprocating sliding

Fundamental tribological studies of a range of engineering polymers, including a bio-derived Polytrimethylene-terephthalate (PTT) have been conducted at low temperatures (12C∘ and −8C∘). The aim of the study was to replace a conventional honed aluminium liner/polytetrafluoroethylene (PTFE) seal interface with a polymer combination, within a Dearman Engine. The Dearman Engine is a novel piston engine driven by the expansion of a cryogenic fluid, either liquid nitrogen or liquid air, to produce emissions-free combined cooling and power. A tribometer was used to simulate engine conditions.The efficacy of the polymers relative to the honed aluminium benchmark was assessed in terms of a projected material transfer layer. The magnitude of which was determined using a combination of scanning electron microscope (SEM)/energy-dispersive X-ray spectroscopy (EDS) and Abbott—Firestone curves, a descriptor of surface texture. The concept of a frictional overshoot, correlated with the severity of wear measured on the PTFE specimen, is introduced.For the engine, a low coefficient of friction (CoF) leads to reduced parasitic losses and low wear will ensure the integrity of the piston seal is maintained, and so to the sealing capacity of the engine. Material transfer, generally from seal to liner specimens was detected in all but the unhoned polyoxymethylene (POM) and unhoned Aluminium samples. These two combinations had the lowest frictional overshoots and the lowest levels of wear. These are properties that were also linked to a low surface roughness and a low gradient of the interquartile range of the Abbott-Firestone curve. These materials both outperformed the benchmark seal/liner combination and the POM provides the potential for an all polymer expansion chamber.

Mitigation of Annulus Pressure Buildup in Offshore Gas Wells by Determination of Top of Cement

Annulus pressure buildup (APB) is still a serious problem in offshore gas wells, which threatens the safety of wells for the entire phases of drilling, completion, and production. The existing methods for mitigating APB are technically complex and highly costly. Setting top of cement (TOC) below the outer casing shoe to mitigate APB is easy to implement and can significantly reduce costs. However, there are no unified methods of determining TOC for this purpose. Nevertheless, existing petroleum standards give ambiguous regulations on the setting of TOC. This article brings a new and cheap method of mitigating APB by determining best TOC settings using a mathematical model for calculating APB from both annulus fluid expansion (AFE) and sustained casing pressure (SCP). Field data from gas well X are inputted to the model to describe how it serves this purpose. Calculation results for well X show that setting TOC's above and below the upper casing shoes for production and intermediate casings annuli, respectively, can greatly avoid the problem of APB and the costs associated with the existing mitigation methods. This technique can be used to other wells following the same procedures. The developed model reduced greatly the ambiguity of TOC determination as it helps to get the clear TOC combinations that control APB at the lowest cost of well construction while maintaining good and safe well operation.

In-Situ Upgrading Process Offers Potential for Heavy-Oil Recovery

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 190695, “Simulations of In-Situ Upgrading Process: Interpretation of Laboratory Experiments and Study of Field-Scale Test,” by A. Perez-Perez, SPE, M. Mujica, and I. Bogdanov, SPE, Computational Hydrocarbon Laboratory for Optimized Energy Efficiency, and A. Brisset, SPE, and O. Garnier, SPE, Total, prepared for the 2018 SPE Improved Oil Recovery Conference, Tulsa, 14–18 April. The paper has not been peer reviewed. In-situ upgrading (IU) is a promising method of improved viscous- and heavy-oil recovery. The IU process involves a reservoir being exposed to temperatures greater than 300°C long enough to promote a series of chemical reactions. In this work, the authors developed a numerical model of IU on the basis of laboratory experiences and validated results, applying the model to an IU test published in the literature. Simulation results for the cores submitted have shown that oil production and oil-sample quality were well-predicted by the model. Introduction In this paper, results of a previously published experiment and those of an unpublished experiment (Experiment B) are modeled and discussed. To accomplish this, an in-house code is developed for coupling the kinetic model with the thermodynamic description, a process detailed in the complete paper. This code was able to represent both the reaction dynamics of bitumen-fraction decomposition and the phase distribution and production of pseudocomponents. The resulting model was used to simulate an IU field-scale test (using data from Shell’s Viking pilot). Experimental Simulation A 2D homogeneous radial model was used to simulate two IU experiments. Elemental gridblock size was 5 mm in both directions. The model size was 5×30 cells (Experiment A) and 5×138 cells (Experiment B). A total of 30 pseudocomponents was provided in the simulation model. A sensitivity analysis was performed to identify the effect of some parameters in the IU model on the basis of experimental conditions in the experiments. This analysis was focused on less-certain properties related to the core and physical properties of oil pseudocomponents. Experimental and Simulation Results. In the process of model development and adaptation, more effort has been dedicated to specify the thermodynamic model than the kinetic model. The final model is capable of successfully predicting liquid production at various test scales and conditions. To explain the mismatch observed between simulation and experimental results of solid generation during IU, the authors performed estimations of solid mass that would be generated under the IU conditions of both experiments in a closed system. The resulting amount of generated solids is the highest possible because the initial hydrocarbons were all retained inside a core. The estimated amount of pyrobitumen for Experiment A was 0.022 kg. This value is still lower than that reported for laboratory conditions (0.024 kg). With regard to Experiment B, taking into account that 35% of the original oil was evacuated by thermal expansion of fluids, the estimated mass of pyrobitumen was approximately 0.070 kg (for closed volume). This value is significantly lower than that reported by the laboratory for this experiment (0.090 kg). The most probable reason is a natural difference in the physicochemical conditions for measurements in kinetic tests and IU experiments.

Investigation on hydrodynamic and formation of nano particle by RESS process: The numerical study

The particle formation by supercritical technology is an active research field. Rapid expansion of supercritical fluid (RESS) is a promising new technology for particle formation using supercritical fluids. In this study, numerical modeling of particle formation of TBTPP (5, 10, 15, 20-tetrakis (3, 5-bis (trifluoromethyl) phenyl) porphyrin) through RESS process is investigated. The RESS process contains two pre-expansion (nozzle part) and expansion vessel (supersonic free jet) parts. In the first section, mass, momentum and energy balances in addition to extended generalized Bender equation of state (egB-EoS) as accurate equation of state is used to calculate temperature, pressure, density and velocity of supercritical carbon dioxide (SC-CO2) based on mathematical modeling and computational fluid dynamics (CFD) simulation methods. Both models include friction in the nozzle and heat exchange in the expansion vessel and in the nozzle region. Using calculated pressure and temperature, the solubility of TBTPP in the supercritical CO2 is predicted by Peng-Robinson EoS with Kwak-Mansoori mixing rule and the results are compared with experimental data and a semi-empirical correlation. Supersaturation, homogenous nucleation and critical radius of TBTPP based on classical nucleation theory are calculated. The effect of pre-expansion temperature on supersaturation, nucleation and critical radius parameters is also studied. The results of hydrodynamic and particle formation modeling present the same trend as reported in the literature.

First-harmonic intrinsic nonlinearity of model polymer solutions in medium amplitude oscillatory shear (MAOS)

First-harmonic MAOS moduli were demonstrated experimentally using monodisperse linear polystyrene (PS) solutions at different concentrations. Two first-harmonic intrinsic nonlinearities are asymptotic deviations from two linear viscoelastic moduli and obtained in medium amplitude oscillatory shear (MAOS) regime. Master curves of first-harmonic MAOS moduli for PS solutions provided novel information which has never been reported before. The interrelationship between first-harmonic and third-harmonic MAOS moduli was evaluated at low and high De. At the low-De limit, all solutions followed the universal interrelation predicted by fourth-order fluid expansion. At the high-De limit, where no universal interrelation exists, the average first-harmonic to third-harmonic elastic MAOS moduli ratio was −22.26, and for viscous counterparts, the magnitude and sign of this ratio changed on increasing frequency. Unentangled and entangled solutions were distinguished using normalized viscous moduli at De > 1. Viscous MAOS moduli normalized by SAOS complex modulus displayed a plateau for unentangled solutions and a decreasing behavior for entangled solutions. First-harmonic MAOS moduli of entangled solutions agreed well with multimode molecular stress function (MSF) predictions under the all relaxation mode assumption, which contrasted with third-harmonic MAOS predictions using the terminal relaxation mode assumption. It is expected that the first-harmonic MAOS results in this paper will be good reference information for future MAOS studies and computer simulations.

Time-strain separability in medium-amplitude oscillatory shear

We derive and study equations for the weakly nonlinear medium-amplitude oscillatory shear (MAOS) response of materials exhibiting time-strain separability. Results apply to constitutive models with arbitrary linear memory function m(s) and for both viscoelastic liquids and viscoelastic solids. The derived equations serve as a reference to identify which models are time-strain separable (TSS) and which may appear separable but are not, in the weakly nonlinear limit. More importantly, we study how the linear viscoelastic (LVE) relaxation spectrum, H(τ), affects the frequency dependence of the TSS MAOS material functions. Continuous relaxation spectra are considered that are associated with analytical functions (log-normal and asymmetric Lorentzian distributions), fractional mechanical models (Maxwell and Zener), and molecular theories (Rouse and Doi-Edwards). TSS MAOS signatures reveal much more than just the perturbation parameter A in the shear damping function small-strain expansion, h(γ)=1+Aγ2+Oγ4. Specifically, the distribution of terminal relaxation times is significantly more apparent in the TSS MAOS functions than their LVE counterparts. We theoretically show that this occurs because TSS MAOS material functions are sensitive to higher-order moments of the relaxation spectrum, which leads to the definition of MAOS liquids. We also show the first examples of MAOS signatures that differ from the liquid-like terminal MAOS behavior predicted by the fourth-order fluid expansion. This occurs when higher moments of the relaxation spectrum are not finite. The famous corotational Maxwell model is a subset of our results here, for which A = −1/6, and any LVE relaxation spectrum could be used.

Drilling Optimization of Tight Sands and Shale Gas Reservoir in Jambi Sub-Basin Based on Pore Pressure Estimation Using Drilling Efficiency Mechanical Specific Energy (DEMSE) and Bowers Methods

The subsurface pressure analysis is used to detect the overpressure and problems in the well that will be drilled based on exploration well data. Various problems were found while drilling operations carried out on A and B wells, namely, Kick and Pipe sticking which cause a high Non-Productive Time (NPT). This research is conducted to identify the mechanism of overpressure formation in Tight Sand Gas and Shale Gas in the Jambi Sub-Basin. Furthermore, to predict pore pressure using the Drilling Efficiency and Mechanical Specific Energy (DEMSE) and Bowers method. The final result will be a 3D pore pressure cube in the area based on quantitative analysis of post-stack seismic inversion. The results of the pore pressure analysis from the wells and the 3D pore pressure model indicate that top of overpressure occurs in the Gumai Formation, then it is decreasing gradually approaching the hydrostatic pressure on the Basement. The mechanisms of overpressure are caused by under compaction, fluid expansion (kerogen maturation). The Gumai Formation and Talang Akar Formation are shale rocks so the type of mud weight that is well used is oil based mud (OBM).

Two-phase flow expansion: development of an innovative test-rig for flow characterisation and CFD validation

The aim of this work is to describe the design of an innovative test rig for investigating the expansion of saturated fluids in the two-phase region. The experimental test rig was thought up and built by TPG of the University of Genoa. It will be equipped by probes and some optical accesses that permit high speed video recording and laser measurements. It will be useful for the study of the quality ratio, vapour and liquid droplet thermodynamic properties and their speed.

Numerical investigation of one-dimensional steady detonation wave characteristics for magnesium particle-air mixture

Magnesium particles have broad application prospects as fuel or additive for detonation combustion power systems due to their high energy density, ignition characteristics and combustion efficiency. In this paper, a one-dimensional steady-state model is established for the magnesium particle-air mixture. The distribution of the flow field and the influences of factors such as phase transition process, inlet velocity, particle radius and initial particle density on the structure of detonation wave are analyzed numerically under different working conditions. The studies have shown that the process accelerating to the sound speed due to the expansion of the gas phase mainly occurs in the pure evaporation reaction stage of the magnesium particles. The duration of magnesium and magnesium oxide melting accounts for a small proportion of the entire combustion process. Under the initial conditions of normal temperature and pressure, the theoretical maximum temperature in the detonation wave during self-sustaining propagation is lower than the dissociation temperature of the magnesium oxide. The heat absorbed in the magnesium melting process is released into the gas phase for expansion work as the reaction progresses, leading to a small effect of magnesium melting on the structure of the detonation wave. The amount of exothermic heat absorbed in the magnesium oxide melting process is so large that the process of expansion of the gaseous working fluid is almost stopped. Moreover, the absorbed heat cannot be used for gas phase expansion work. Therefore, the melting process of magnesium oxide has a great influence on the structure of the detonation wave. The detonation wave of the magnesium particle-air mixture can be stabilized and self-sustained only at the eigenvalue velocity. Below this value, a singular point appears in the flow field. Above this value, the wave cannot be accelerated to the speed of sound, and the downstream flow field disturbance can pass through the reaction combustion zone and weaken the intensity of the detonation wave. When the end of the detonation wave is in the melting process, the detonation wave can still stabilize the self-sustaining propagation when a certain inflow velocity and a magnesium particle density are satisfied. Otherwise, the detonation wave can propagate only at an average speed with oscillation. The initial particle concentration corresponding to the peak of the eigenvalue velocity is smaller than the stoichiometric one corresponding to the peaks of the density, pressure and temperature, indicating that the eigenvalue velocity is not dependent solely on the heat release of the reaction because the interaction between the two phases also affects the conversion efficiency of thermal energy into gas phase kinetic energy. Under the premise of uniform distribution of internal temperature of magnesium particles, the particle size mainly affects the size of the detonation wave, but has little effect on the characteristic value of the eigenvalue velocity and the Chapman-Jouguet parameters. The model in this paper comprehensively reflects the influence of the phase transition process in the combustion process on the structure of the detonation wave and the self-sustaining propagation mechanism. It has a certain guiding significance for designing the detonation power device using powder fuel.

Peramalan Kinerja Lapangan SNP Dengan Injeksi Air Menggunakan Metode Material Balance

The decline in production from of a field is the common problem in the oil and gas industry. One of the causes of the decrease in production is the decline of reservoir pressure. Based on the analisis result, it was found that SNP field had a weak water drive. The most dominant drive of the field was fluid expansion. In order to reduce the problem, a reservoir pressure maintenance effort was required by injecting water. In this research, the effect of water injection to reservoir pressure and cumulative production was analyzed. From the evaluation result, it was found that the existing inejection performance using one injection well to Zones A and B was not optimum. Because, the recovery factor was predicted to 29.11% only.By activating the four injection wells, the recoverty factor could be increase to 31.43%.

Models of Anisotropic Self-Gravitating Source in Einstein-Gauss-Bonnet Gravity

In this paper, we have studied gravitational collapse and expansion of nonstatic anisotropic fluid in 5D Einstein-Gauss-Bonnet gravity. For this purpose, the field equations have been modeled and evaluated for the given source and geometry. The two metric functions have been expressed in terms of parametric form of third metric function. We have examined the range of parameter β (appearing in the form of metric functions) for which Θ, the expansion scalar, becoming positive/negative leads to expansion/collapse of the source. The trapped surface condition has been explored by using definition of Misner-Sharp mass and auxiliary solutions. The auxiliary solutions of the field equations involve a single function that generates two types of anisotropic solutions. Each solution can be represented in term of arbitrary function of time; this function has been chosen arbitrarily to fit the different astrophysical time profiles. The existing solutions forecast gravitational expansion and collapse depending on the choice of initial data. In this case, wall to wall collapse of spherical source has been investigated. The dynamics of the spherical source have been observed graphically with the effects of Gauss-Bonnet coupling term α in the case of collapse and expansion. The energy conditions are satisfied for the specific values of parameters in both solutions; this implies that the solutions are physically acceptable.

Hydrodynamics with spacetime-dependent scattering length

Hydrodynamics provides a concise but powerful description of long-time and long-distance physics of correlated systems out of thermodynamic equilibrium. Here we construct hydrodynamic equations for nonrelativistic particles with a spacetime-dependent scattering length and show that it enters constitutive relations uniquely so as to represent the fluid expansion and contraction in both normal and superfluid phases. As a consequence, we find that a leading dissipative correction to the contact density due to the spacetime-dependent scattering length is proportional to the bulk viscosity (${\ensuremath{\zeta}}_{2}$ in the superfluid phase). Also, when the scattering length is slowly varied over time in a uniform system, the entropy density is found to be produced even without fluid flows in proportion to the bulk viscosity, which may be useful as a novel probe to measure the bulk viscosity in ultracold-atom experiments.

A novel educational laboratory experiment for constant-mass expansion of petroleum fluids

This paper presents a new way to conduct an educational experiment for bubble-point determination of a hydrocarbon mixture. The visual fluid cell newly designed for educational purposes made it possible to teach bubble-point determination safely at low cost within a few hours for groups of students in a laboratory class. The educational experiment developed has been successfully implemented for three semesters at the authors’ institution with positive responses from a vast majority of the students. It is hoped that this paper helps other interested instructors enhance students’ learning experience in the subject of fluid properties.

Right Ventricular and Pulmonary Vascular Function are Influenced by Age and Volume Expansion in Healthy Humans

Patients with heart failure (HF) often show signs of right ventricular (RV) dysfunction. The RV function of coupled with the pulmonary circulation (tricuspid annular plane systolic excursion [TAPSE]/pulmonary arterial systolic pressure [PASP]) has been shown to divide HF patients into distinct prognostic strata, but less is known about which factors influence this prognostic marker, and whether those factors can be modified. We sought to obtain normative values and discern the individual effects of age, sex, and fluid overload on RV function. Sixty healthy subjects aged 20-80 years were enrolled in this prospective study. Right heart catheterization with hemodynamic measurements were performed at rest after a rapid saline solution infusion (10 mL/kg, 150 mL/min). Linear regression and Spearman correlation models were used to estimate associations between TAPSE/PASP and relevant variables. In healthy persons of all ages, the median (5th-95th percentiles) normative TASPE-PASP ratio was 1.25 (0.81-1.78) mm/mm Hg. The correlation between progressive age and declining TAPSE/PASP was significant (r = -0.35; P = .006). Sex did not influence TAPSE/PASP (P = .30). Rapid fluid expansion increased central venous pressure from 5 ± 2 mm Hg to 11 ± 4 mm Hg after fluid infusion (P < .0001). This resulted in a 32% decrease in the TAPSE-PASP ratio after fluid infusion, compared to baseline (P < .0001). The TAPSE-PASP ratio was affected by age, but not sex. TAPSE/PASP is not only a reflection of intrinsic RV function and pulmonary vascular coupling, but fluid status also dynamically affects this index of RV function. Normative values with invasive measurements were obtained for future assessment of HF patients.

Additive effect of bFGF and selenium on expansion and paracrine action of human amniotic fluid-derived mesenchymal stem cells

BackgroundMesenchymal stem cell-derived conditioned medium (MSC-CM) has emerged as a promising cell-free tool for restoring degenerative diseases and treating traumatic injuries. The present study describes the effect of selenium as a reactive oxygen species (ROS) scavenger and its additive effect with basic fibroblast growth factor (bFGF) on in vitro expansion of amniotic fluid (AF)-MSCs and the paracrine actions of AF-MSC-CM as well as the associated cellular and molecular mechanisms.MethodsIn this study, we obtained CM from human AF-MSCs cultured with selenium. The stemness of selenium-treated AF-MSCs was evaluated by cell growth and differentiation potential. Human fibroblasts were treated with AF-MSC-CM and analyzed for cell signaling changes. For in vivo wound healing assay, ICR mice with a full-thickness skin wound were used.ResultsSelenium played a critical role in in vitro expansion of AF-MSCs through activation of the AKT-ERK1/2, Smad2, and Stat3 signaling pathways along with inactivation of GSK3β. When administered together with bFGF, it showed remarkable effect in inhibiting ROS accumulation and preserving their multipotency. Proliferation and migration of human dermal fibroblasts and in vivo wound healing were improved in the CMs derived from AF-MSCs exposed to selenium and bFGF, which was caused by the Smad2, AKT-MEK1/2-ERK, and NFκB signaling triggered by the paracrine factors of AF-MSCs, such as TGF-β, VEGF, and IL-6. Our results suggest the following: (a) supplementation of selenium in AF-MSC culture contributes to in vitro expansion and preservation of multipotency, (b) ROS accumulation causes progressive losses in proliferative and differentiation potential, (c) the separate activities of bFGF and selenium in MSCs exert an additive effect when used together, and (d) the additive combination improves the therapeutic effects of AF-MSC-derived CMs on tissue repair and regeneration.ConclusionAntioxidants, such as selenium, should be considered as an essential supplement for eliciting the paracrine effects of MSC-CMs.

Hydrocarbon-Gas Cycling Improves Recovery in the Arun Gas Field

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 186280, “Review of 20 Years of Hydrocarbon-Gas Cycling in the Arun Gas Field,” by Suhendro, SPE, Pertamina Hulu Energi, prepared for the 2017 SPE/IATMI Asia Pacific Oil and Gas Conference and Exhibition, Bali, Indonesia, 17–19 October. The paper has not been peer reviewed. Lean-gas injection has been used as an alternative method in gas fields to maintain reservoir pressure, minimize condensate banking near the wellbore, and mitigate oversupply operations during low-market periods. In this paper, past gas-cycling operations were examined to identify subsurface implications and effects on operability aspects for the Arun giant gas field offshore Indonesia in the North Sumatra Basin. Production and pressure data show that gas cycling contributes significantly to the improvement of field-recovery factors. Reservoir and Fluid Description The Arun gas field was discovered in 1971. The formation is carbonate reef, created during the Miocene age. It lies between two thick shale layers, Bampo on the bottom and Baong on the top. The Bampo formation is identified as source rock, with Baong shale as caprock. The field trends north to south, with a width of 18.5 km and a length of 5 km. Gas/water contact, to the south and west, was tilted toward the southern part of the field. A gas-condensate reservoir at a depth of 10,000 ft was found to have an average thickness of 503 ft and an area of 21,450 acres, with 7,100-psig initial pressure and a temperature of 352°F. Initial condensate/gas ratio (CGR) was 50 bbl/MMcf. The reservoir has 16.2% average porosity and 17% initial water saturation. Volumetric original gas in place (OGIP) is calculated to be 17 scf. The current production rate from the field is approximately 80 MMcf/D with 2,400 bbl of condensate/day. Fluid expansion and gas injection are determined to be the two main drive mechanisms on the basis of material-balance analysis. Hydrocarbon production uses four clusters with approximately 21 wells in each cluster. Each cluster is equipped with the same typical surface facilities. All produced fluid is pooled at Point A before being piped to gas-processing facilities. Initially, the produced gas was delivered to the Arun liquefied natural gas (LNG) plant for liquefaction but, in late 2014, the plant was shut down because of contract termination. In the second quarter of 2015, the facilities were reactivated for an LNG regasification terminal, Perta Arun Gas (PAG). Currently, the produced gas is transported to PAG for separation and dehydration before downstream processing. The northern part of the field contains fair porosity; the middle part is dominated by good and fair porosity, while the southern part has a greater incidence of poor porosity. Clusters II and III, which are located at the middle part, contribute more cumulative gas production and condensate compared with Clusters I and IV. Thus, better reservoir properties and parameters are contributing to better production.